GOVPH

Sex: Male
Education

• Doctor of Philosophy in Geology, University of Cambridge, United Kingdom 2001

Field of Specialization

Remote Sensing
Landslides
Tectonics
Natural Disasters
Earthquake
Geodynamics
Geomorphology
Geography
Geology
Disaster Management

Researches:

Article title: Hazardous base surges of Taal's 2020 eruption
Authors: Alfredo Mahar Lagmay, Rosana B Tarriela, Mario A. Aurelio, Richard Ybañez
Publication title: Scientific Reports 11(15703), August 2021

Abstract:
After 43 years of repose, Taal Volcano erupted on 12 January 2020 forming hazardous base surges. Using field, remote sensing (i.e. UAV and LiDAR), and numerical methods, we gathered primary data to generate well-constrained observed information on dune bedform characteristics, impact dynamic pressures and velocities of base surges. This is to advance our knowledge on this type of hazard to understand and evaluate its consequences and risks. The dilute and wet surges traveled at 50-60 ms −1 near the crater rim and decelerated before making impact on coastal communities with dynamic pressures of at least 1.7 kPa. The base surges killed more than a thousand livestock in the southeast of Taal Volcano Island, and then traveled another ~ 600 m offshore. This work is a rare document of a complete, fresh, and practically undisturbed base surge deposit, important in the study of dune deposits formed by volcanic and other processes on Earth and other planets.
Full text link: https://tinyurl.com/n64usw9c

Article title: Statistical Analysis of Building Damage from the 2013 Super Typhoon Haiyan and its Storm Surge in the Philippines
Authors: Tanaporn Chaivutitorn, Thawalrat Tanasakcharoen, Natt Leelawat, Jing Tang
Publication title: Journal of Disaster Research 15(7):822-832, December 2020

Abstract:
In November 2013, Super Typhoon Haiyan (Yolanda) hit the Philippines. It caused heavy loss of lives and extensive damages to buildings and infrastructure. When collapsed buildings are focused on, it is interesting to find that these buildings did not collapse for the same reasons after the landfall of the typhoon and storm surge. The objective of this study is to develop a statistical model for building damage due to Super Typhoon Haiyan and its storm surge. The data were collected in collaboration with Tanauan Municipality, the Philippines. The data for the inundation map were obtained by field surveys conducted on-site to determine the cause of the damages inferred from satellite data. The maximum wind speed was derived from the Holland parametric hurricane model based on the Japan Meteorological Agency (JMA) typhoon track data and the inundation depth of storm surge was calculated using the MIKE model. Multinomial logistic regression was used to develop a model to identify the significant factors influencing the damage to buildings. The result of this work is expected to be used to prepare urban plans for preventing damage from future storms.
Full text link: https://tinyurl.com/dt7y5c8w

Article title: Anatomy of the Naga City Landslide and Comparison With Historical Debris Avalanches and Analog Models
Authors: Alfredo Mahar Lagmay, Carmille Marie J. Escape, Audrei Anne Bonus Ybanez, John Kenneth Suarez, et al.
Publication title: Frontiers in Earth Science 8, August 2020

Abstract:
Debris avalanches pose some of the most destructive geologic hazards that threaten both urban and rural populations around the world. On 20 September 2018, villages in Naga City, Cebu, Philippines, were devastated by a landslide that claimed 78 lives with 6 missing, joining other catastrophic landslides in the country like the 1628 Iriga and the 2006 Guinsaugon debris avalanches. Understanding the mechanism of these gargantuan landslides and their correct nomenclature are useful for hazard prevention and mitigation. In this study, we compare the deposit characteristics of the Naga City landslide with analog models and well-known historical debris avalanche events/deposits in the Philippines to understand factors that led to the landslide disaster in Naga City. Physical characteristics obtained from aerial and satellite imagery, ground surveys, recorded footage, borehole data, and lithologic maps provided a detailed dataset for analyzing the conditions that led to the mass movement and the observed characteristics of the Naga landslide deposits. Comparison with analog models of hummock formation and the description of historical debris avalanche deposits show striking similarities, which were used to demonstrate that the Naga landslide was a Rockslide-Debris Avalanche. The equations of Corominas (1996) and Dade and Huppert (1998) for long-runout rockfalls support this analysis. The Naga landslide event is an example of a well-documented debris avalanche, complete with all the characteristics of this type of rapid mass movement. It is consistent with the descriptions found in the literature with respect to its deposit features and mechanical behavior as defined by laboratory models and empirically-derived equations. This study helps us understand historical and future long-runout debris avalanches in order for scientists and authorities to find ways to save lives. Unfortunately, there was lack of appropriate hazards assessment on the site, which had warnings in the form of the development of fractures at the headscarp of the landslide, a month prior to the disaster.
Full text link: https://tinyurl.com/muxxsu4w

Article title: Shallow seismic reflection imaging of the Inabanga–Clarin portion of the North Bohol Fault, Central Visayas, Philippines
Authors: Romer Carlo Gacusan and Alfredo Mahar Lagmay
Publication title: Geoscience Letters 6(1):10, September 2019

Abstract:
On 15 October 2013, a magnitude 7.2 earthquake was generated from a previously unidentified fault in the island of Bohol. This fault was named the North Bohol Fault (NBF) by authorities. We investigated the geometry of the Ina-banga–Clarin portion of the NBF using three high-resolution shallow seismic reflection profiles to image sections of the fault up to 150 m depth not seen in trenching and regional offshore seismic profiles. These seismic profiles are along the Calubian, Napo, and Caluwasan transects which run perpendicular to the N 40◦ E strike of the NBF. Reverse faults were identified in the Calubian and Napo profiles, whereas a positive flower structure was seen in the Calu-wasan profile. Normal faults were also identified in the Caluwasan and Napo profiles. This study corroborates the observations in earlier trenching studies that measured the reverse fault dip angle and direction of the NBF at 70◦SE. It also demonstrates that topographic flexures are the surface manifestation of steeply dipping faults. The down-thrown block of the reverse faults in the Calubian profile defines a depression on the surface; the Napo seismic profile displacement of 3 m is consistent with the 3-m-high surface rupture in Barangay Anonang; and the flower structure in the Caluwasan profile is related to the pressure ridge and right lateral offset stream on the surface. Furthermore, the presence of normal faults as well as the other deformational features is consistent with the transpressional regime described in the literature, wherein the principal horizontal stress is oriented NW–SE. These findings complement earlier geomorphic and trenching investigations of the NBF and demonstrate the application of a tool to image the subsurface and characterize undescribed or hidden faults, which is necessary for earthquake hazard assessment and attendant risk mitigation and prevention planning.
Full text link: https://tinyurl.com/2ysj8c97

Article title: Lessons from tropical storms Urduja and Vinta disasters in the Philippines
Authors: Alfredo Mahar Lagmay and Bernard Alan Baluyut Racoma
Publication title: Disaster Prevention and Management, October 2018

Abstract:
Purpose Tropical storms Urduja and Vinta battered the Philippines in December 2017. Despite advances in disaster risk reduction efforts of the country, the twin December storms caused numerous deaths in the Visayas and Mindanao regions. Analysis of these events shows that alerts raised during the Pre-Disaster Risk Assessment (PDRA) for both storms were largely ineffective because they were too broad and general calling for forced evacuations in too many provinces. Repeated multiple and general warnings that usually do not end up in floods or landslides, desensitize people and result in the cry-wolf effect where communities do not respond with urgency when needed. It was unlike the previous execution of PDRA from 2014 to early 2017 by the National Disaster Risk Reduction and Management Council (NDRRMC), which averted mass loss of lives in many severely impacted areas because of hazard-specific, area-focused and time-bound warnings. PDRA must reinstate specific calls, where mayors of communities are informed by phone hours in advance of imminent danger to prompt and ensure immediate action. Mainstreaming Climate Change Adaptation and Disaster Risk Reduction information using probabilistic (multi-scenario) hazard maps is also necessary for an effective early warning system to elicit appropriate response from the community. The paper aims to discuss these issues. Design/methodology/approach Methods of early warning through the PDRA of the National Disaster Mitigation and Management Council (NDRRMC) of the Philippines during tropical storm Urduja and Typhoon Vinta were assessed in this study and compared to the previous PDRA system from 2014 to early 2017. Findings It was found out that the numerous casualties were due to inadequate warning issued during the approach of the tropical cyclones. During an impending hazard, warnings must be accurate, reliable, understandable and timely. Despite the availability of maps that identified safe zones for different communities, warnings raised during the PDRA for both tropical cyclones were deemed too general calling for evacuations of whole provinces. As such, not all communities were evacuated in a timely manner because of failure in the key elements of an effective early warning system. Originality/value To avoid future disasters from happening, it is recommended that the PDRA reinstate its hazards-specific, area-focused and time-bound warnings. Similarly, to increase the resilience of communities, more work on mainstreaming of Climate Change Adaptation and Disaster Risk and Vulnerability Reduction systems for communities must be done as well. Learning from the lessons of these previous disasters will enable communities, their leaders and every stakeholder, not to repeat the same mistakes in the future.
Full text available upon request to the author

Article title: Street floods in Metro Manila and possible solutions
Authors: Alfredo Mahar Lagmay, Jerico E. Mendoza, Fatima Cipriano, Patricia Anne Delmendom, et al.
Publication title: Journal of Environmental Sciences 59, March 2017

Abstract:
Urban floods from thunderstorms cause severe problems in Metro Manila due to road traffic. Using Light Detection and Ranging (LiDAR)-derived topography, flood simulations and anecdotal reports, the root of surface flood problems in Metro Manila is identified. Majority of flood-prone areas are along the intersection of creeks and streets located in topographic lows. When creeks overflow or when rapidly accumulated street flood does not drain fast enough to the nearest stream channel, the intersecting road also gets flooded. Possible solutions include the elevation of roads or construction of well-designed drainage structures leading to the creeks. Proposed solutions to the flood problem of Metro Manila may avoid paralyzing traffic problems due to short-lived rain events, which according to Japan International Cooperation Agency (JICA) cost the Philippine economy 2.4 billion pesos/day.
Full text link: https://tinyurl.com/359thms6

Article title: Disseminating near-real-time hazards information and flood maps in the Philippines through Web-GIS
Authors: Alfredo Mahar Lagmay, Bernard Alan Baluyut Racoma, Ken Adrian Aracan, Jenalyn Alconis-Ayco, et al.
Publication title: Journal of Environmental Sciences 1(201), March 2017

Abstract:
The Philippines being a locus of tropical cyclones, tsunamis, earthquakes and volcanic eruptions, is a hotbed of disasters. These natural hazards inflict loss of lives and costly damage to property. Situated in a region where climate and geophysical tempest is common, the Philippines will inevitably suffer from calamities similar to those experienced recently. With continued development and population growth in hazard prone areas, it is expected that damage to infrastructure and human losses would persist and even rise unless appropriate measures are immediately implemented by government. In 2012, the Philippines launched a responsive program for disaster prevention and mitigation called the Nationwide Operational Assessment of Hazards (Project NOAH), specifically for government warning agencies to be able to provide a 6. hr lead-time warning to vulnerable communities against impending floods and to use advanced technology to enhance current geo-hazard vulnerability maps. To disseminate such critical information to as wide an audience as possible, a Web-GIS using mashups of freely available source codes and application program interface (APIs) was developed and can be found in the URLs http://noah.dost.gov.ph and http://noah.up.edu.ph/. This Web-GIS tool is now heavily used by local government units in the Philippines in their disaster prevention and mitigation efforts and can be replicated in countries that have a proactive approach to address the impacts of natural hazards but lack sufficient funds.
Full text available upon request to the author

Article title: The December 2012 Mayo River debris flow triggered by Super Typhoon Bopha in Mindanao, Philippines: Lessons learned and questions raised
Authors: Kelvin Rodolfo, Alfredo Mahar Lagmay, Rodrigo Eco, Tatum Miko L. Herrero, et al.
Publication title: Natural Hazards and Earth System Sciences 16(12):2683-2695, December 2016

Abstract
Category 5 Super Typhoon Bopha, the world's worst storm of 2012, formed abnormally close to the Equator, and its landfall on Mindanao set the record proximity to the Equator for its category. Its torrential rains generated an enormous debris flow in the Mayo River watershed that swept away much of the village Andap in the New Bataan municipality, burying areas under rubble as thick as 9 m and killing 566 people. Established in 1968, New Bataan had never experienced super typhoons and debris flows. This unfamiliarity compounded the death and damage. We describe Bopha's history, debris flows and the Mayo River disaster, and then we discuss how population growth contributed to the catastrophe, as well as the possibility that climate change may render other near-Equatorial areas vulnerable to hazards brought on by similar typhoons. Finally, we recommend measures to minimize the loss of life and damage to property from similar future events.
Full text link: https://tinyurl.com/bdrvs5ts

Article title: Delineation of alluvial fans from Digital Elevation Models with a GIS algorithm for the geomorphological mapping of the Earth and Mars
Authors: Gianluca Norini, Maria Clara Zuluaga, Iris Jill Ortiz, Dakila Aquino Chow, et al.
Publication title: Geomorphology 273, November 2016

Abstract
No available
Full text available upon request to the author

Article title: The December 2012 Mayo River debris flow triggered by Super Typhoon Bopha in Mindanao, Philippines: Lessons learned and questions raised
Authors: Kelvin Rodolfo, Alfredo Mahar Lagmay, Rodrigo Eco, Tatum Miko L. Herrero, et al.
Publication title: Natural Hazards and Earth System Sciences Discussions, April 2016

Abstract
Category 5 Super Typhoon Bopha, the world's worst storm of 2012, formed abnormally close to the Equator, and its landfall on Mindanao set the record proximity to the Equator for its category. Its torrential rains generated an enormous debris flow in the Mayo River watershed that swept away much of Andap village in New Bataan municipality, burying areas under rubble as thick as 9 meters and killing 566 people. Established in 1968, New Bataan had never experienced super typhoons and debris flows. This unfamiliarity compounded the death and damage. We describe Bopha's history, debris flows and the Mayo River disaster, then discuss how population growth contributed to the catastrophe, and the possibility that climate change may render other near-Equatorial areas vulnerable to hazards brought by similar typhoons. Finally, we recommend measures to minimize the loss of life and damage to property from similar, future events.
Full text link: https://tinyurl.com/mc3na9pm

Article title: Hazard mapping related to structurally controlled landslides in Southern Leyte, Philippines
Authors: Paul Kenneth Luzon, Kristina Montalbo, Jam Galang, Jasmine May Sabado, et al.
Publication title: Natural Hazards and Earth System Sciences 16(3):875-883, April 2016

Abstract
The 2006 Guinsaugon landslide in Saint Bernard, Southern Leyte, is one of the largest known landslides in the Philippines in recent history. It consists of a 15–20 million m3 rockslide-debris avalanche from an approximately 675 m high mountain weakened by continuous movement of the Philippine Fault. The catastrophic Guinsaugon landslide killed 1221 people and displaced 19 000 residents over its 4.5 km path. To investigate the present-day morphology of the scar and potential failure that may occur, analysis of a 5 m resolution InSAR-derived digital elevation model was conducted using Coltop3D and Matterocking software, leading to the generation of a landslide hazard map for the province of Southern Leyte in central Philippines. The dip and dip direction of discontinuity sets that contribute to gravitational failure in mountainous areas of the province were identified and measured using a lower Schmidt–Lambert color scheme. After measurement of the morpho-structural orientations, potential sites of failure were analyzed. Conefall was then utilized to compute the extent of rock mass runout. Results of the analysis show instability in the scarp area of the 2006 Guinsaugon landslide and in adjacent slopes because of the presence of steep discontinuities that range from 45 to 60°. Apart from the 2006 Guinsaugon landslide site, runout models simulated farther rock mass extent in its adjacent slopes, revealing a high potential for fatal landslides to happen in the municipality of Saint Bernard. Concerned agencies may use maps produced in the same manner as this study to identify possible sites where structurally controlled landslides can occur. In a country like the Philippines, where fractures and faults are common, this type of simulated hazard maps would be useful for disaster prevention and facilitate disaster risk reduction efforts for landslide-susceptible areas.
Full text link: https://tinyurl.com/54vxus5t

Article title: 3D modeling of the Buhi debris avalanche deposit of Iriga Volcano, Philippines by integrating shallow-seismic reflection and geological data
Authors: Likha Minimo and Alfredo Mahar Lagmay
Publication title: Journal of Volcanology and Geothermal Research 319, March 2016

Abstract
Numerical models for simulating volcanic debris avalanches commonly lack a critical initiation parameter, the source volume, which is difficult to estimate without data on the deposit thickness. This, in turn, limits how rheology can be characterized for simulating flow. Leapfrog Geo, a 3D geological modeling software, was used to integrate shallow-seismic reflection profiles with field and borehole data to determine the volume of the Buhi debris avalanche and the pre-collapse structure of Iriga Volcano. Volumes of the deposit calculated in this way are 34–71% larger than previous estimates. This technique may improve models of debris avalanches elsewhere in the world, and more precisely depict landslide runout and lateral extent, thus improving disaster prevention and mitigation for the many cities located near volcanoes.
Full text available upon request to the author

Article title: Shallow landslide susceptibility mapping using high-resolution topography for areas devastated by super typhoon Haiyan
Authors: Maricar Rabonza, Raquel Felix, Alfredo Mahar Lagmay, Rodrigo Eco, et al.
Publication title: Landslides 13(1):201-210, February 2016

Abstract
Super typhoon Haiyan, considered as one of the most powerful storms recorded in 2013, devastated the central Philippines region on 8 November 2013 with damage amounting to more than USD 2 billion. Hardest hit is the province of Leyte which is located in central Philippines. Rehabilitation of the areas that were devastated requires detailed hazard maps as a basis for well-planned reconstruction. Along with severe wind, storm surge, and flood hazard maps, detailed landslide susceptibility maps for the cities and municipalities of Leyte (7246.7 km2) province are necessary. In order to rapidly assess and delineate areas susceptible to rainfall-induced shallow landslides, Stability INdex MAPping (SINMAP) software was used over a 5-m Interferometric Synthetic Aperture Radar (InSAR)-derived digital terrain model (DTM) grid. Topographic, soil strength, and hydrologic parameters were used for each pixel of a given DTM grid to compute for the corresponding factor of safety. The landslide maps generated using SINMAP are highly consistent with the landslide inventory derived from high-resolution satellite imagery from 2002 to 2014 with a detection percentage of 97.5 % and missing factor of 0.025. These demonstrate that SINMAP performs well despite the lack of an extensive geotechnical and hydrological database in the study area. The detailed landslide susceptibility classification is useful to identify safe and unsafe areas for reconstruction and rehabilitation efforts. These maps complement the debris flow and structurally controlled landslide hazard maps that are also being prepared for rebuilding Haiyan’s devastated areas.
Full text available upon request to the author

Article title: Integrating and Applying Technology in Response to the Super Typhoon Bopha Disaster
Authors: Michael A. Ross, Joy Santiago, Alfredo Mahar Lagmay
Publication title: Procedia Engineering, December 2015

Abstract
The Philippines is recognized as one of the most natural hazard prone country in the world. The December 4, 2012 Super Typhoon Bopha (referred is the Philippines as Typhoon Pablo) and the November 8, 2013 Super Typhoon Haiyan (Yolanda) are recent major disasters which The Louis Berger Group (Louis Berger) was requested by the U.S. Agency for International Development (USAID) to rapidly respond to. Louis Berger quickly identified partners and appropriate technologies, which it applied during these post-disaster recovery activities, strengthening the requested response and building local capacity and preparedness for future natural disasters and responses. This paper is based on the vulnerability assessment (VA) component of the Louis Berger's contracted role in responding to the Typhoon Pablo event. The major USAID-funded Louis Berger response to Typhoon Yolanda is ongoing with current contract completion scheduled in June 2016.
Full text link: https://tinyurl.com/tzfwppdt

Article title: The Journal of the PGRSS and its significance in Philippine space technology applications
Authors: Alfredo Mahar Lagmay
Publication title: Journal of the Philippine Geoscience and Remote Sensing Society 1(1), September 2015

Abstract
As early as 1970, the Philippines exploited satellite remote sensing technology to monitor weather disturbances from polar orbiting spacecraft. Not only did the country use remote sensing technology for atmospheric observations, it was also quick to realize its benefits in late 1977 to identify different forest types and for monitoring forest cover. Since then, the technology was applied to accomplish many specific objectives. Although there is an active community of practitioners in this field, there has been no local journal dedicated to remote sensing where Filipinos have their work scientifically reviewed, shared, and discussed. The launch of the Journal of the Philippine Geosciences and Remote Sensing (PGRSS), through this maiden issue, marks an era of revival in the use of space technology in the country. It is greatly motivated by the recent acquisition of LiDAR instruments, a hyperspectral imager, Doppler Radar, drones, a nationwide, IFSAR-derived Digital Elevation Model (DEM), and fabrication of Philippine-made microsatellites. Like the need for the use of local capacity and local resources for effective disaster risk reduction and prevention, this journal addresses the need to support the local community of remote sensing scientists for fast, clear, and efficient communication of scientific output. This forum, hopefully will serve its purpose to advance our understanding of complex earth processes for national development.
Full text link: https://tinyurl.com/4tzw8r74

Article title: Structurally controlled hazard mapping of Southern Leyte, Philippines
Authors: P. K. Luzon, K. P. Montalbo, Jan Albert Briones Galang, J. M. Sabado, et al.
Publication title: Natural Hazards and Earth System Sciences Discussions 3(10):5891-5921, October 2015

Abstract
The 2006 Guinsaugon landslide in St. Bernard, Southern Leyte is one of the largest known landslides in the Philippines in recent history. It consists of a 15–20 million m3 rockslide-debris avalanche from an approximately 675 m high mountain weakened by continuous movement of the Philippine fault. The catastrophic Guinsaugon landslide killed 1221 people and displaced 19 000 residents over its 4.5 km path. To investigate the present day morphology of the scar and potential failure that may occur, analysis of a 5 m resolution IfSAR-derived Digital Elevation Model was conducted using Coltop3D and Matterocking software, leading to the generation of a landslide hazard map for the province of Southern Leyte in Central Philippines. The dip and dip-direction of discontinuity sets that contribute to gravitational failure in mountainous areas of the province were identified and measured using a lower Schmidt-Lambert color scheme. After measurement of the morpho-structural orientations, potential sites of failure were analyzed. Conefall was then utilized to compute the extent of rock mass runout. Results of the analysis show instability in the scarp area of the 2006 Guinsaugon landslide and in adjacent slopes because of the presence of steep discontinuities that range from 45–60°. Apart from the 2006 Guinsaugon landslide site, runout models simulated farther rock mass extent in its adjacent slopes, revealing a high potential for fatal landslides to happen in the municipality of St. Bernard. Concerned agencies may use maps produced in the same manner as this study to identify possible sites where structurally-controlled landslides can occur. In a country like the Philippines, where fractures and faults are common, this type of simulated hazard maps would be useful for disaster prevention and facilitate disaster risk reduction efforts for landslide-susceptible areas.
Full text link: https://tinyurl.com/rntmj2n8

Article title: Block and boulder transport in Eastern Samar (Philippines) during Supertyphoon Haiyan
Authors: Simon Matthias May, Max Engel, Dominik Brill, Camille Cuadra
Publication title: Earth Surface Dynamics Discussions 3(3):739-771, August 2015

Abstract
Fields of dislocated boulders and blocks record catastrophic coastal flooding during strong storms or tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar (Philippines) we documented longshore transport of a block of 180 t and boulders (up to 23.5 t) shifted uphill to elevations of up 5 to 10 m above mean lower low water level during Supertyphoon Haiyan on 8 Novem-ber 2013. Initiation-of-motion approaches indicate that boulder dislocation occurred with flow velocities of 6.3–8.3 m s −1 which significantly exceeds depth-averaged flow velocities of a local coupled hydrodynamic and wave model (Delft3D) of the typhoon with a maximum < 1.5 m s −1. These results support the hypothesis that infragravity 10 waves induced by the typhoon were responsible for the remarkable flooding pattern in E Samar, which are not resolved in phase-averaged storm surge models. Our findings show that tsunamis and hydrodynamic conditions induced by tropical cyclones may shift boulders of similar size and, therefore, demand to carefully reassess the possibility of storm-related transport where it, based on the boulder's sheer size, has previously 15 been ascribed to tsunamis.
Full text available upon request to the author

Article title: Identification of storm surge vulnerable areas in the Philippines through the simulation of Typhoon Haiyan-induced storm surge levels over historical storm tracks
Authors: John Phillip Bartolome Lapidez, Judd P. Tablazon, Lea Dasallas, Lia Gonzalo, et al.
Publication title: Natural Hazards and Earth System Sciences Discussions 3(2):919-939, July 2015

Abstract
Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR) on 7 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the storm surge and strong winds. Storm surges up to a height of 7 m were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled researchers of the Nationwide Operational Assessment of Hazards (Project NOAH) which is the flagship disaster mitigation program of the Department of Science and Technology (DOST) of the Philippine government to undertake a study to determine the vulnerability of all Philippine coastal communities to storm surges of the same magnitude as those generated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running simulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948–2013. One product of this study is a list of the 30 most vulnerable coastal areas that can be used as a basis for choosing priority sites for further studies to implement appropriate site-specific solutions for flood risk management. Another product is the storm tide inundation maps that the local government units can use to develop a risk-sensitive land use plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.
Full text available upon request to the author

Article title: Identification of storm surge vulnerable areas in the Philippines through the simulation of Typhoon Haiyan-induced storm surge levels over historical storm tracks
Authors: Alfredo Mahar Lagmay
Publication title: Natural Hazards and Earth System Sciences, July 2015

Abstract
Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR) on 7 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the storm surge and strong winds. Storm surges up to a height of 7 m were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled re- searchers of the Nationwide Operational Assessment of Hazards (Project NOAH) which is the flagship disaster mitiga- tion program of the Department of Science and Technology (DOST) of the Philippine government to undertake a study to determine the vulnerability of all Philippine coastal commu- nities to storm surges of the same magnitude as those gener- ated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running sim- ulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948–2013. One product of this study is a list of the 30 most vulnerable coastal areas that can be used as a basis for choosing priority sites for fur- ther studies to implement appropriate site-specific solutions for flood risk management. Another product is the storm tide inundation maps that the local government units can use to develop a risk-sensitive land use plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.
Full text link: https://tinyurl.com/tfpuuja8

Article title: Storm-surge models helped for Hagupit
Authors: Alfredo Mahar Lagmay and Norman Kerle
Publication title: Nature 519(7544):414, March 2015

Abstract
The Philippine government learned from shortcomings in the preparations for Typhoon Haiyan in 2013 (see R. Lejano et al. Nature 518, 35; 2015, and A. M. F. Lagmay et al. Int. J. Disaster Risk Reduct. 11, 1–12; 2015) and was able to limit the damage that last December’s Typhoon Hagupit might otherwise have caused. For example, storm surges during Haiyan extended inland by an unanticipated 2 kilometres. Specific warnings of surges of up to 5.5 metres were issued two days before Haiyan’s landfall, and were broadcast on primetime television by the country’s president. Despite this, the warnings proved inadequate because the variability of coastal landscapes makes it impossible to judge inundation extent on the basis of storm-surge heights alone. Following the 2013 disaster, Project NOAH (run by the Philippine government’s Department of Science and Technology) prepared stormsurge inundation maps for all its coastal provinces, modelled using high-resolution topography. These detailed maps, along with advance warning, helped to mitigate the loss of life when Hagupit’s storm surges destroyed at least 1,800 homes at the end of 2014.
Full text available upon request to the author

Article title: Probabilistic storm surge inundation maps for Metro Manila based on Philippine public storm warning signals
Authors: Judd P. Tablazon, C. V. Caro, Alfredo Mahar Lagmay, J. B. L. Briones, et al.
Publication title: Natural Hazards and Earth System Sciences 15(3):557-570, March 2015

Abstract
A storm surge is the sudden rise of sea water over the astronomical tides, generated by an approaching storm. This event poses a major threat to the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013. This hydro-meteorological hazard is one of the main reasons for the high number of casualties due to the typhoon, with 6300 deaths. It became evident that the need to develop a storm surge inundation map is of utmost importance. To develop these maps, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH) simulated historical tropical cyclones that entered the Philippine Area of Responsibility. The Japan Meteorological Agency storm surge model was used to simulate storm surge heights. The frequency distribution of the maximum storm surge heights was calculated using simulation results of tropical cyclones under a specific public storm warning signal (PSWS) that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of inundation for a specific PSWS using the probability of exceedance derived from the frequency distribution. Buildings and other structures were assigned a probability of exceedance depending on their occupancy category, i.e., 1% probability of exceedance for critical facilities, 10% probability of exceedance for special occupancy structures, and 25% for standard occupancy and miscellaneous structures. The maps produced show the storm-surge-vulnerable areas in Metro Manila, illustrated by the flood depth of up to 4 m and extent of up to 6.5 km from the coastline. This information can help local government units in developing early warning systems, disaster preparedness and mitigation plans, vulnerability assessments, risk-sensitive land use plans, shoreline defense efforts, and coastal protection measures. These maps can also determine the best areas to build critical structures, or at least determine the level of protection of these structures should they be built in hazard areas. Moreover, these will support the local government units' mandate to raise public awareness, disseminate information about storm surge hazards, and implement appropriate countermeasures for a given PSWS.
Full text link: https://tinyurl.com/kkc4prya

Article title: Typhoons: Storm-surge models helped for Hagupit
Authors: Alfredo Mahar Lagmay and Norman Kerle
Publication title: Nature 519(7544):414, March 2015

Abstract
The Philippine government learned from shortcomings in the preparations for Typhoon Haiyan in 2013 (see R. Lejano et al. Nature 518, 35; 2015, and A. M. F. Lagmay et al. Int. J. Disaster Risk Reduct. 11, 1–12; 2015) and was able to limit the damage that last December’s Typhoon Hagupit might otherwise have caused. For example, storm surges during Haiyan extended inland by an unanticipated 2 kilometres. Specific warnings of surges of up to 5.5 metres were issued two days before Haiyan’s landfall, and were broadcast on prime-time television by the country’s president. Despite this, the warnings proved inadequate because the variability of coastal landscapes makes it impossible to judge inundation extent on the basis of storm-surge heights alone. Following the 2013 disaster, Project NOAH (run by the Philippine government’s Department of Science and Technology) prepared storm-surge inundation maps for all its coastal provinces, modelled using high-resolution topography. These detailed maps, along with advance warning, helped to mitigate the loss of life when Hagupit’s storm surges destroyed at least 1,800 homes at the end of 2014.
Full text link: https://tinyurl.com/cjjdzh2j

Article title: Volcanoes magnify Metro Manila's southwest monsoon rains and lethal floods
Authors: Alfredo Mahar Lagmay, Gerry Bagtasa, Irene A Crisologo, Bernard Alan Baluyut Racoma, et al.
Publication title: Frontiers in Earth Science 2(39), December 2014

Abstract
Many volcanoes worldwide are located near populated cities that experience monsoon seasons, characterised by shifting winds each year. Because of the severity of flood impact to large populations, it is worthy of investigation in the Philippines and elsewhere to better understand the phenomenon for possible hazard mitigating solutions, if any. During the monsoon season, the change in flow direction of winds brings moist warm air to cross the mountains and volcanoes in western Philippines and cause lift into the atmosphere, which normally leads to heavy rains and floods. Heavy southwest monsoon rains from 18-21 August 2013 flooded Metro Manila (population of 12 million) and its suburbs paralyzing the nation’s capital for an entire week. Called the 2013 Habagat event, it was a repeat of the 2012 Habagat or extreme southwest monsoon weather from 6-9 August, which delivered record rains in the mega city. In both the 2012 and 2013 Habagat events, cyclones, the usual suspects for the delivery of heavy rains, were passing northeast of the Philippine archipelago, respectively, and enhanced the southwest monsoon. Analysis of Doppler data, rainfall measure- ments, and Weather Research and Forecasting (WRF) model simulations show that two large stratovolcanoes, Natib and Mariveles, across from Manila Bay and approximately 70 km west of Metro Manila, played a sub- stantial role in delivering extreme rains and consequent floods to Metro Manila. The study highlights how volcanoes, with their shape and height create an orographic effect and dispersive tail of rain clouds which constitutes a significant flood hazard to large communities like Metro Manila.
Full text available upon request to the author

Article title: Devastating storm surges of Typhoon Haiyan
Authors: Alfredo Mahar Lagmay, Rojelee P. Agaton, Mark Allen C. Bahala, Jo Brianne Louise T. Briones, et al.
Publication title: International Journal of Disaster Risk Reduction 11, October 2014

Abstract
On 8th November 2013, Typhoon Haiyan, local name Yolanda, made landfall in the central Philippine islands region. Considered one of the most powerful typhoons ever to make landfall in recorded history, the 600 km diameter Typhoon Haiyan crossed the Philippine archipelago, bringing widespread devastation in its path. Strong winds, heavy rainfall, and storm surges caused extreme loss of lives and widespread damage to property. Storm surges were primarily responsible for the 6300 dead, 1061 missing and 28,689 injured in Haiyan's aftermath. Here, we document the storm surge simulations which were used as basis for the warnings provided to the public 2 days prior to the howler's landfall. We then validate the accounts based on field data and accounts provided in the news. The devastating Haiyan storm surges are one of the biggest in several decades, which exacted a high death toll despite its early prediction. There were many lessons learned from this calamity, and information contained in this work may serve as useful reference to mitigate the heavy impact of future storm surge events in the Philippines and elsewhere.
Full text available upon request to the author

Article title: Brief Communication: On the source characteristics and impacts of the magnitude 7.2 Bohol earthquake, Philippines
Authors: Alfredo Mahar Lagmay and Rodrigo Eco
Publication title: Natural Hazards and Earth System Sciences 14(10):2795-2801, October 2014

Abstract
A devastating earthquake struck Bohol, Philippines, on 15 October 2013. The earthquake originated at 12 km depth from an unmapped reverse fault, which manifested on the surface for several kilometers and with maximum vertical displacement of 3 m. The earthquake resulted in 222 fatalities with damage to infrastructure estimated at USD 52.06 million. Widespread landslides and sinkholes formed in the predominantly limestone region during the earthquake. These remain a significant threat to communities as destabilized hillside slopes, landslide-dammed rivers and incipient sinkholes are still vulnerable to collapse, triggered possibly by aftershocks and heavy rains in the upcoming months of November and December. The most recent fatal temblor originated from a previously unmapped fault, herein referred to as the Inabanga Fault. Like the hidden or previously unmapped faults responsible for the 2012 Negros and 2013 Bohol earthquakes, there may be more unidentified faults that need to be mapped through field and geophysical methods. This is necessary to mitigate the possible damaging effects of future earthquakes in the Philippines.
Full text available upon request to the author

Article title: Developing an early warning system for storm surge inundation in the Philippines
Authors: J. Tablazon, C. V. Caro, Alfredo Mahar Lagmay, J. B. L. Briones, et al.
Publication title: Natural Hazards and Earth System Sciences Discussions 2(10):6241-6270, October 2014

Abstract
A storm surge is the sudden rise of sea water generated by an approaching storm, over and above the astronomical tides. This event imposes a major threat in the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013 where more than 6000 people lost their lives. It has become evident that the need to develop an early warning system for storm surges is of utmost importance. To provide forecasts of the possible storm surge heights of an approaching typhoon, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH) simulated historical tropical cyclones that entered the Philippine Area of Responsibility. Bathymetric data, storm track, central atmospheric pressure, and maximum wind speed were used as parameters for the Japan Meteorological Agency Storm Surge Model. The researchers calculated the frequency distribution of maximum storm surge heights of all typhoons under a specific Public Storm Warning Signal (PSWS) that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of probable area inundation and flood levels of storm surges along coastal areas for a specific PSWS using the results of the frequency distribution. These maps were developed from the time series data of the storm tide at 10 min intervals of all observation points in the Philippines. This information will be beneficial in developing early warnings systems, static maps, disaster mitigation and preparedness plans, vulnerability assessments, risk-sensitive land use plans, shoreline defense efforts, and coastal protection measures. Moreover, these will support the local government units' mandate to raise public awareness, disseminate information about storm surge hazards, and implement appropriate counter-measures for a given PSWS.
Full text available upon request to the author

Article title: Brief communication "The magnitude 7.2 Bohol earthquake, Philippines"
Authors: Alfredo Mahar Lagmay and R. Eco
Publication title: Natural Hazards and Earth System Sciences Discussions 2(3), February 2014

Abstract
A devastating earthquake struck Bohol, Philippines on 15 October 2013. The earthquake originated at 12 km depth from an unmapped reverse fault, which manifested on the surface for several kilometers and with maximum vertical displacement of 3 m. The earthquake resulted in 222 fatalities with damage to infrastructure estimated at US52.06 million. Widespread landslides and sinkholes formed in the predominantly limestone region during the earthquake. These remain a significant threat to communities as destabilized hillside slopes, landslide-dammed rivers and incipient sinkholes are still vulnerable to collapse, triggered possibly by aftershocks and heavy rains in the upcoming months of November and December.
Full text link: https://tinyurl.com/3z64tut6

Article title: Hummocks: How they form and how they evolve in rockslide-debris avalanches
Authors: Engielle Mae Raot-raot Paguican, Benjamin van Wyk de Vries, Alfredo Mahar Lagmay
Publication title: Landslides 11(1), February 2014

Abstract
Hummocks are topographic features of large landslides and rockslide-debris avalanches common in volcanic settings. We use scaled analog models to study hummock formation and explore their importance in understanding landslide kinematics and dynamics. The models are designed to replicate large-scale volcanic collapses but are relevant also to non-volcanic settings. We characterize hummocks in terms of their evolution, spatial distribution, and internal structure from slide initiation to final arrest. Hummocks initially form by extensional faulting as a landslide begins to move. During motion, individual large blocks develop and spread, creating an initial distribution, with small hummocks at the landslide front and larger ones at the back. As the mass spreads, hummocks can get wider but may decrease in height, break up, or merge to form bigger and long anticlinal hummocks when confined. Hummock size depends on their position in the initial mass, modified by subsequent breakup or coalescence. A hummock has normal faults that flatten into low-angle detachments and merge with a basal shear zone. In areas of transverse movement within a landslide, elongate hummocks develop between strike–slip flower structures. All the model structures are consistent with field observations and suggest a general brittle-slide emplacement for most landslide avalanches. Absence of hummocks and fault-like features in the deposit may imply a more fluidal flow of emplacement or very low cohesion of lithologies. Hummocks can be used as kinematic indicators to indicate landslide evolution and reconstruct initial failures and provide a framework with which to study emplacement dynamics.
Full text link https://tinyurl.com/23ra9ps9

Article title: Brief Communication: On the source characteristics and impacts of the magnitude 7.2 Bohol earthquake, Philippines
Authors: Alfredo Mahar Lagmay
Publication title: Natural Hazards and Earth System Sciences 14:1-7, January 2014

Abstract
A devastating earthquake struck Bohol, Philip- pines, on 15 October 2013. The earthquake originated at 12 km depth from an unmapped reverse fault, which mani- fested on the surface for several kilometers and with maxi- mum vertical displacement of 3 m. The earthquake resulted in 222 fatalities with damage to infrastructure estimated at USD 52.06 million. Widespread landslides and sinkholes formed in the predominantly limestone region during the earthquake. These remain a significant threat to communi- ties as destabilized hillside slopes, landslide-dammed rivers and incipient sinkholes are still vulnerable to collapse, trig- gered possibly by aftershocks and heavy rains in the upcom- ing months of November and December. The most recent fatal temblor originated from a previously unmapped fault, herein referred to as the Inabanga Fault. Like the hidden or previously unmapped faults responsible for the 2012 Negros and 2013 Bohol earthquakes, there may be more unidentified faults that need to be mapped through field and geophysical methods. This is necessary to mitigate the possible damaging effects of future earthquakes in the Philippines.
Full text link https://tinyurl.com/ye529aay

Article title: Volcano-tectonic controls and emplacemnt kinematics of the Iriga debris avalanches (Philippines)
Authors: Engielle Mae Raot-raot Paguican, Benjamin van Wyk de Vries, Alfredo Mahar Lagmay
Publication title: Bulletin of Volcanology 74(9), November 2012

Abstract
Mt Iriga in southeastern Luzon is known for its spectacular collapse scar that was possibly created in 1628 ad by a 1.5-km3 debris avalanche. The debris avalanche deposit (DAD) covered 70 km2 and dammed the Barit River to form Lake Buhi. The collapse has been ascribed to a non-volcanic trigger related to a major strike-slip fault under the volcano. Using a combination of fieldwork and remote sensing, we have identified a similar size, older DAD to the southwest of the edifice that originated from a sector oblique to the underlying strike-slip fault. Both deposits cover wide areas of low, waterlogged plains, to a distance of about 16 km for the oldest and 12 km for the youngest. Hundreds of metre-wide and up to 50-m-high hummocks of intact conglomerate, sand and clay units derived from the base of the volcano show that the initial failure planes cut deep into the substrata. In addition, large proportions of both DAD consist of ring-plain sediments that were incorporated by soft-sediment bulking and extensive bulldozing. An ignimbrite unit incorporated into the younger DAD forms small (less than 5 m high) discrete hummocks between the larger ones. Both debris avalanches slid over water-saturated soft sediment or ignimbrite and spread out on a basal shear zone, accommodated by horst and graben formation and strike-slip faults in the main mass. The faults are listric and flatten into a well-developed basal shear zone. This shear zone contains components from the substrate and has a diffuse contact with the intact substrata. Long, transport-normal ridges in the distal parts are evidence of compression related to deceleration and bulldozing. The collapse orientation and structure on both sectors and DAD constituents are consistent with collapse being a response to combined transtensional faulting and gravity spreading. Iriga can serve as a model for other volcanoes, such as Mayon, that stand in sedimentary basins undergoing transtensional strike-slip faulting.
Full text available upon request to the author

Article title: Terrestrial smokers: Thermal springs due to hydrothermal convection of groundwater connected to surface water
Authors: M. Bayani Cardenas, Alfredo Mahar Lagmay, Benjamin J. Andrews, Raymond S. Rodolfo, et al.
Publication title: Geophysical Research Letters 39(2):2403, January 2012

Abstract
Thermal springs are ubiquitous features whose underground kinematic structure is mostly unknown but are typically thought to originate from deep sources. We documented a type of thermal springs at the banks of a volcanic lake that are discharge zones of hydrothermal convection cells circulating groundwater within the near shore environment. The convection captures lake water through the lakebed, mixes it with deeper groundwater at velocities of 100s of m d-1, then returns the water to the lake via the spring. The convection cell is flushed in a few hours and turns over the lake's volume in a few days. Most volcanic lakes and other relatively cool surface water bodies in areas of elevated geothermal heat fluxes meet the conditions for the occurrence of local hydrothermal circulation of groundwater. The type of spring we studied, the terrestrial version of black smokers, is likely present but perhaps unrecognized at many areas.
Full text link https://tinyurl.com/889s9yuj

Article title: Geological hazards of SW Natib Volcano, site of the Bataan Nuclear Power Plant, the Philippines
Authors: Alfredo Mahar Lagmay, Raymond S. Rodolfo, H. Cabria, J. Soria, et al.
Publication title: Geological Society London Special Publications 361(1):151-169, January 2012

Abstract
The SW sector of Mount Natib, a potentially active volcano in the Bataan volcanic arc in western Luzon, is the site of a mothballed nuclear power plant that members of the national legislature have proposed to activate. Detailed geological fieldwork was conducted to assess the capability of the volcano and to identify any volcanic hazards it might pose to the nuclear plant. The nearest eruptive centre is 5.5 km away from the plant. SW Natib Volcano is underlain by lava flows, lahar deposits and at least six pyroclastic density current (PDC) deposits, three directly underlying the nuclear reactor facility. A fault trending N30°E is aligned with the Lubao Fault, a capable fault NE of the volcanic edifice. Radon emissions at the traces of these faults are high and comparable to those at known active faults. An associated thrust fault at the nuclear site cuts through lahars up to the ground surface. The results presented here can be used for general hazard preparedness of local communities, and may assist the government to decide whether or not to recommission the nuclear power plant.
Full text link https://tinyurl.com/47j6hv2d

Article title: Configuration of the Geothermal Prospects in the Leyte Geothermal Reservation (Philippines) and Implications of a Volcano-Tectonic Framework in Exploration
Authors: Joeffrey A Caranto, Lauro F Bayrante, Alfredo Mahar Lagmay, Francisco A Lagmay, et al.
Publication title: Proceedings World Geothermal Congress April 2010

Abstract
The island of Leyte in The Philippines hosts the largest developed liquid-dominated geothermal system in the world. The Leyte geothermal production field is located within the Leyte geothermal reservation along with several other geothermal prospects that are adjacent to areas with Neogene to Pleistocene period of volcanism (Bayrante & Palma, 1987). This field is located in the northern flank of the eroded Ancestral Mount Bao (AMB) volcano (Lagmay et al., 2003). The other prospects southeast of LGPF are Alto Peak, Lobi, Mahagnao and Bato Lunas, all located within the traverse of the Philippine Fault System. Several exploration well drilling in Alto Peak, Lobi, and Mahagnao have proven the existence of high temperature volcanic systems with different physical and chemical reservoir characteristics. Alto Peak hosts an immature geothermal system related to a young volcanic center. Lobi and Mahagnao, on the other hand, have encountered high temperature systems but the reservoir is within the basement ultramafic complex that is inherently impermeable. These geothermal prospects have yet to fully develop for power generation. Recent analysis of volcano-tectonic structures and analog sand cone experiments indicate that the existing producing wells in LGPF straddle the crypto-Philippine fault, a master fault that induced fracture-controlled permeability within the geothermal field. The structural model suggests that the southern flank of the AMB directly above the southern extension of the master Philippine Fault is an ideal geothermal target (Lagmay et al., 2003). The drilling of a deep well in Lobi in 2003 did not reach this postulated extensional area so the above structural model has not been confirmed. However, considering these latest structural analyses, the area south of LGPF within the concave side of the identified sigmoid structure may warrant further detailed geoscientific studies for geothermal exploration.
Full text link https://tinyurl.com/52h67v4s

Article title: The perfect storm: Floods devastate manila
Authors: Alfredo Mahar Lagmay, Raymond S. Rodolfo, Mary Grace Bato
Publication title: Earth 55(4):51, April 2010

Abstract
No available
Full text link https://tinyurl.com/wn8w2wcn

Article title: Getting to know Kelvin
Authors: Alfredo Mahar Lagmay
Publication title: Philippine Science Letters 3(1), 2010

Abstract
Pinatubo's eruption in 1991, a tall white-bearded man stood in the Mayor's office of Olongapo. Surrounded by a throng of terrified men and sacs of foreign mail, he spoke in English and Ilocano, advising everyone to remain calm as Pinatubo vented its fury. D This was the first time I saw Kelvin Rodolfo. He was 54 years of age and I was 25. That single encounter with Kelvin forever changed my life from a Geologist to a Volcanologist. He did not do anything out of his ordinary self to make this impression. He was just there when it mattered, and simply spoke his science in his usual passionate way. It took a decade before I really came to know him, when he became an adjunct faculty member at the National Institute of Geological Sciences, University of the Philippines; his office merely three rooms away. He would visit U.P. annually for a few months to work with Dr. Siringan and some other colleagues in the department. As I regarded him as an iconic figure, he seemed difficult to approach. But an Oxfam funded research work at the lake of Pinatubo changed all that, enabling me to work with Kelvin and break through his intimidating facade. It turns out he is a gentle, humorous and sensitive man. Mayon Lahars In 1984, Kelvin began to conduct pioneering research work on Mayon lahars funded initially by the National Science and Technology Authority (NSTA), Philippines, and later by the National Science Foundation (NSF), USA. At that time, lahars were a poorly understood phenomenon. Usage of the term lahar created more confusion that it led many volcanologists and sedimentologists to recommend the word to be discarded entirely. Experts suggested that debris flows be adopted instead, as it was a more general term used to describe fast-moving landslides that had consistency of wet concrete.
Full text link: https://tinyurl.com/yu4h3hk9

Article title: New Definition of Philippine Plate Boundaries and Implications to the Philippine Mobile Belt
Authors: Alfredo Mahar Lagmay, Maria Luisa Tejada, Mario A. Aurelio, Rolando Pena, et al.
Publication title: Journal of the Geological Society of the Philippines 64(1), January-December 2009

Abstract
The Philippine Mobile Belt (PMB) is a zone of intense deformation and active seismicity between convergent zones bounding the Philippine Archipelago. This zone was first defined by Gervasio (1967) to distinguish the seismically active portion of the Philippine Archipelago from the southwestern region of the Philippines. According to Gervasio, the “mobile belt”, includes North Luzon, South Luzon, West Visayas, Northwest Mindanao, Bicol Region, East Visayas, Zamboanga, Cotabato and the rest of Mindanao with Catanduanes Island representing the east outer zone of the PMB. The aseismic region, on the other hand, is constituted by Palawan and Mindoro. In the plate tectonics framework, the PMB represents a zone of deformation between surrounding major plates, namely: the Philippine Sea, Eurasian (Sunda Block) and Indo-Australian Plates. Only Palawan and Mindoro, the aseismic regions of the Philippines are part of the Eurasian Plate. Based on recent Global Positioning System, gravity, and seismicity data, we reinterpret Philippine Plate boundaries that define the extent of the Philippine Mobile Belt. The eastern section of North Luzon, heretofore described as part of the PMB, moves in a northwest direction with similar velocity as the Philippine Sea Plate. This suggests that the northwestward motion of the Philippine Sea Plate at the eastern margin of Luzon is mainly decoupled along the left-lateral Polilio-Philippine fault zone. The Polilio-Philippine fault is a zone of intense seismicity and is herein regarded as the crustal tear generated by the ongoing collision of the Benham Rise with Luzon starting from 20 Ma. This interpretation considers the eastern section of North Luzon as part of the Philippine Sea Plate and has major implications to the delineation of plate boundaries of the Philippines.
Full text link https://tinyurl.com/3n6s7ydk

Article title: Extreme rainfall-induced lahars and dike breaching, 30 November 2006, Mayon Volcano, Philippines
Authors: Engielle Mae Raot-raot Paguican, Alfredo Mahar Lagmay, Raymond S. Rodolfo, Kelvin Rodolfo, et al.
Publication title: Bulletin of Volcanology 71(8):845-857, October 2009

Abstract
On 29–30 November 2006, heavy rains from Supertyphoon Durian remobilized volcanic debris on the southern and eastern slopes of Mount Mayon, generating major lahars that caused severe loss of life and property in downstream communities. The nearby Legaspi City weather station recorded 495.8mm of rainfall over 1.5days at rates as high as 47.5mm/h, far exceeding the initiation threshold for Mayon lahars. For about 18h, floods and lahars from the intense and prolonged rainfall overtopped river bends, breaching six dikes through which they created new paths, buried downstream communities in thick, widespread deposits, and caused most of the 1,266 fatalities. In order to mitigate damage from future lahars, the deposits were described and analyzed for clues to their generation and impact on structures and people. Post-disaster maps were generated from raw ASTER and SPOT images, using automated density slicing to characterize lahar deposits, flooded areas, croplands, and urbanized areas. Fieldwork was undertaken to check the accuracy of the maps, especially at the edges of the lahar deposits, and to measure the deposit thicknesses. The Durian event was exceptional in terms of rainfall intensity, but the dikes eventually failed because they were designed and built according to flood specifications, not to withstand major lahars.
Full text link https://tinyurl.com/4yu9n8be

Article title: Quaternary sector collapses of Nevado de Toluca volcano (Mexico) governed by regional tectonics and volcanic evolution
Authors: Gianluca Norini, Lucia Capra, Gianluca Groppelli, Alfredo Mahar Lagmay
Publication title: Geosphere 4(5), October 2008

Abstract
Nevado de Toluca volcano is an andesitic- dacitic composite volcano of Late Pliocene– Holocene age located in the central-eastern sector of the Trans-Mexican Volcanic Belt, an active continental arc. The latest stage of Nevado de Toluca evolution, in the past 50 k.y., has shown an interplay between vol- canic activity and kinematics of the basement structures. Geological mapping, stratigraphic analysis, morphological and structural inter- pretation, and analogue modeling were used to investigate these complex volcano-tectonics relationships. In the past 50 k.y., Nevado de Toluca volcano underwent at least three sec- tor collapses on the east, east-southeast, and west flanks because of faulting and destabili- zation of young dacitic domes at its summit. Field and remotely sensed data supported by analogue models of transtensive basement tectonics revealed that these catastrophic events were strongly correlated to the pres- ence of the east-west–striking active Tenango fault system. The geometry, kinematics, and dynamics of the basement structure con- trolled the growth of a dome complex in the volcano summit and its destabilization. As a consequence of the active basement tectonics, the most probable sector collapse directions in the case of future gravitational failures of the volcano summit will be east-southeast, west-northwest, east, and west. Nevado de Toluca poses potential hazards to more than 25 million inhabitants; the analysis presented in this paper can improve hazard mitigation on the basis of better knowledge of growth and collapse mechanism of the volcano. The numerous examples of composite volcanoes in continental and island volcanic arcs with sim- ilar structural-volcanological characteristics of Nevado de Toluca volcano imply that the model results can also act as a guide to study the growth and collapse of other composite volcanoes affected by basement structures.
Full text link https://tinyurl.com/whw7uaft

Article title: ASTER-based study of the night-time urban heat island effect in Metro Manila
Authors: M. Tiangco, Alfredo Mahar Lagmay, J. Argete
Publication title: International Journal of Remote Sensing 29(10):2799-2818, May 2008

Abstract:
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was used to derive land surface temperatures to quantify the night‐time urban heat island (UHI) effect in Metro Manila. Temperature differences between Metro Manila and its adjacent rural towns were compared to determine heat island intensity and analyse spatial variation of surface temperature. Transects were drawn across from the rural to the urban region to characterize the UHI profile and the Normalized Difference Vegetation Index (NDVI) was used to examine the relationship between amount of vegetation and temperature. The thermal images revealed the highest UHI intensity to be 2.96°C with the presence of a heat island existing in the central part of the city. The transects described the cross‐sectional heat island profile characterized by gradients of ‘cliffs’, ‘plateaus’ and a ‘peak’ occurring in the city centre. The study also showed an inverse relationship between NDVI and temperature, which suggests that increasing the amount of plants in cities can reduce the UHI effect.
Full text link: https://tinyurl.com/wc4mcfee

Article title: Influence of substrate tectonic heritage on the evolution of composite volcanoes: Predicting sites of flank eruption, lateral collapse, and erosion
Authors: Alessandro Tibaldi, Andrey Kozhurin, Alfredo Mahar Lagmay, Claudia Corazzato, et al.
Publication title: Global and Planetary Change 61:151-174, April 2008

Abstract
This paper aims to aid understanding of the complicated interplay between construction and destruction of volcanoes, with an emphasis on the role of substrate tectonic heritage in controlling magma conduit geometry, lateral collapse, landslides, and preferential erosion pathways. The influence of basement structure on the development of six composite volcanoes located in different geodynamic/geological environments is described: Stromboli (Italy), in an island arc extensional tectonic setting, Ollagüe (Bolivia–Chile) in a cordilleran extensional setting, Kizimen (Russia) in a transtensional setting, Pinatubo (Philippines) in a transcurrent setting, Planchon (Chile) in a compressional cordilleran setting, and Mt. Etna (Italy) in a complex tectonic boundary setting. Analogue and numerical modelling results are used to enhance understanding of processes exemplified by these volcanic centres. We provide a comprehensive overview of this topic by considering a great deal of relevant, recently published studies and combine these with the presentation of new results, in order to contribute to the discussion on substrate tectonics and its control on volcano evolution. The results show that magma conduits in volcanic rift zones can be geometrically controlled by the regional tectonic stress field. Rift zones produce a lateral magma push that controls the direction of lateral collapse and can also trigger collapse. Once lateral collapse occurs, the resulting debuttressing produces a reorganization of the shallow-level magma migration pathways towards the collapse depression. Subsequent landslides and erosion tend to localize along rift zones. If a zone of weakness underlies a volcano, long-term creep can occur, deforming a large sector of the cone. This deformation can trigger landslides that propagate along the destabilized flank axis. In the absence of a rift zone, normal and transcurrent faults propagating from the substrate through the volcano can induce flank instability in directions respectively perpendicular and oblique to fault strike. This destabilization can evolve to lateral collapse with triggering mechanisms such as seismic activity or magmatic intrusion.
Full text available upon request to the author

Article title: Science guides search and rescue after the 2006 Philippine landslide
Authors: Alfredo Mahar Lagmay, Arlene Tengonciang, Raymond S. Rodolfo, Janneli Lea A. Soria, et al.
Publication title: Disasters 32(3):416 - 433, March 2008

Abstract:
A rockslide-debris avalanche destroyed the remote village of Guinsaugon in Southern Leyte, Philippines, on 17 February 2006. Although search and rescue procedures were implemented immediately, the scale of the landslide and a lack of information about its nature resulted in unfocused and imprecise efforts in the early days of the operation. Technical support was only introduced five days after the event, provided by a team of volunteer geologists, geophysicists, and meteorologists. By the time search and rescue operations were transferred to specific target sites, however, the chances of finding survivors trapped under the rubble had diminished. In such critical situations, speed, accuracy, and the maximum appropriation of resources are crucial. We emphasise here the need for a systematic and technically informed approach to search and rescue missions in large-scale landslide disaster contexts, and the formulation of better disaster management policies in general. Standard procedures must be developed and enforced to improve how civil authorities respond to natural calamities.
Full text available upon request to the author

Article title: Geology and hazard implications of the Maraunot notch in the Pinatubo Caldera, Philippines
Authors: Alfredo Mahar Lagmay, Kelvin Rodolfo, F. P. Siringan, H. Uy, et al.
Publication title: Bulletin of Volcanology 69(7):797-809, January 2007

Abstract:
The 1991 Pinatubo eruption left 5–6km3 of debris on the volcano slopes, much of which has been mobilized into large lahars in the following rainy seasons. Also during the eruption, collapse, localized in part along preexisting faults, left a caldera 2.5km in diameter that almost immediately began to accumulate a 1.6 × 108m3 lake. By 2001, the water had risen to the fault-controlled Maraunot Notch, the lowest, northwestern portion of the caldera rim comprising the physiographic sill of the Caldera Lake. That year, a narrow artificial canal dug into an old volcanic breccia underlying the outlet channel failed to induce a deliberate lake breakout, but discharge from heavy rains in July 2002 rapidly deepened the notch by 23m, releasing an estimated 6.5 × 107m3 of lake water that bulked up into lahars with a volume well in excess of 1.6 × 108m3. Lakes in other volcanoes have experienced multiple breakouts, providing practical motivation for this study. Fieldwork and high-resolution digital elevation models reveal andesites and ancient lacustrine deposits, strongly fractured and deformed along a segment of the Maraunot Fault, a prominent, steeply dipping, left-lateral fault zone that trends N35°–40°W within and parallel to the notch. Seismicity in 1991 demonstrated that the Maraunot Fault is still active. The fault zone appears to have previously been the erosional locus for a large channel, filled with avalanche or landslide deposits of an earlier eruption that were exhumed by the 2002 breakout floods. The deformed lacustrine sediments, with an uncalibrated 14C age of 14,760 ± 40year BP from a single charcoal sample, attest to the existence of an earlier lake, possibly within the Tayawan Caldera, rim remnants of which survive as arcuate escarpments. That lake may well have experienced one or more ancient breakouts as well. The 2002 event greatly reduced the possibility of another such event by scouring away the erodible breccia, leaving less erodible fractured andesites and lacustrine rocks, and by enlarging the outlet channel and its discharge capacity. Several lines of evidence indicate, however, that future lahar-generating lake breakouts at the notch may keep populations of Botolan municipality downstream at risk: (1) a volume of 9.5 × 107m3 of lake water remains perched 0.8km above sea level; (2) seismicity in 1991 demonstrated that the Maraunot Fault is still active and movements of sufficient magnitude could enlarge the outlet and the discharge through it; (3) more likely, however, with or without earthquake activity, landslides from the steep to overhanging channel walls could block the channel again, and a major rainstorm could then cause a rise in lake level and sudden breakouts; (4) intrusion of a new dome into the bottom of the lake, possibly accompanied by phreatic explosions, could expel large volumes of lahar-generating water.
Full text link https://tinyurl.com/y2r3kfyf

Article title: Regional stress influence on the opening direction of crater amphitheaters in Southeast Asian volcanoes
Authors: Alfredo Mahar Lagmay and W. Valdivia
Publication title: Journal of Volcanology and Geothermal Research 158(1):139-150, November 2006

Abstract:
Holocene volcanoes in the Philippines and Indonesia were studied to determine the possible relationship between the regional maximum horizontal stress (σHmax) and the opening direction of volcanic amphitheatre craters. The study was conducted using publicly available Shuttle Radar Topographic Mission (SRTM) images and the World Stress Map (WSM). The results corroborate findings in similar research on Japanese and Indonesian volcanoes indicating that opening of craters occur at an acute angle relative to the σHmax direction. Further investigation of volcanoes in Southwest and Southeast Luzon, Philippines, regions where fault structures and their kinematics are better constrained, reveal a promising tectonic stress-related rationale for crater opening direction. Several volcanoes in these regions of the Philippines appear to have amphitheatre craters open in the direction related to the fault underlying the volcano. These observations are consistent with those derived from analogue models of volcanic cones deformed by basal strike-slip faulting. These findings can be useful in advancing our understanding of volcanic flank failure and for hazards preparedness against such catastrophic events.
Full text available upon request to the author

Article title: Recent left-oblique slip faulting in the central eastern Trans-Mexican Volcanic Belt: Seismic hazard and geodynamic implications
Authors: Gianluca Norini, Gianluca Groppelli, Alfredo Mahar Lagmay, Lucia Capra
Publication title: Tectonics 25(4), August 2006

Abstract:
Detailed structural analysis was conducted on the E-W trending Tenango Fault System (TFS) at the western end of the La Pera Fault System, a major structure within the Trans-Mexican Volcanic Belt (TMVB). Field mapping, which included trenching the fault trace, revealed the displacement of recent volcanic deposits. The study indicates that the TFS is an active subvertical fault with transtensive left-lateral movement consistent with the contemporary stress regime in the region. The estimated Holocene slip rate is 0.3–0.5 mm/yr. The TFS activity constitutes an important seismic hazard in the intra-arc Lerma basin. Several towns are located within this basin and are particularly vulnerable to seismic risk because of its underlying strata consisting of lacustrine and volcaniclastic deposits (estimated maximum Mw 6.8–7). The TFS is an important structural element in the complex tectonic deformation history of central eastern TMVB and influenced the behavior of recent volcanism within the Lerma basin.
Full text link https://tinyurl.com/rt8a72t9

Article title: Trenching studies of active faults in Kamchatka, eastern Russia: Palaeoseismic, tectonic and hazard implications
Authors: Andrey Kozhurin, Valerio Acocella, Philip Kyle, Alfredo Mahar Lagmay, et al.
Publication title: Tectonophysics 417(3):285-304, May 2006

Abstract:
The central part of the Kamchatka Peninsula is characterized by a well defined depression associated with active volcanism, aligned NE–SW. On the east, the depression is bounded by a prominent system of active faults known as the East Kamchatka Fault Zone (EKFZ). In order to improve understanding of the behaviour and kinematic role of this fault zone a fieldwork programme, including study of trenches, was conducted in the north-central part of this system. Aerial photograph analysis, ground-truthed, indicates a westward fault dip with predominantly normal slip, while lateral offsets of river terraces and stream channels demonstrate a combined dextral component. Over 20 excavated pits and natural exposures were examined to confirm a detailed tephra succession extending from the early Holocene to recent historic eruptions. This chronological framework then provided age control on five past faulting events recognised in three trenches. These events took place at about 10.5, 6.0, 4.5 and, in a two-event succession within a short time span, at 3.3–3.2 ka BP. Event clustering may be characteristic and fault length–displacement values suggest earthquakes of M6.5, thus representing a significant new element in regional seismic hazard evaluations; additional to events generated at the subduction interface. The relatively long gap in faulting since the two most recent events may also be significant for hazard scenarios and there is a possible link between the faulting and volcanic activity in the depression. Overall, the EKFZ, together with the Nachiki Transverse Zone farther south, is thought to define a regional-scale block that is extending eastwards independently from the rest of Kamchatka.
Full text link: https://tinyurl.com/dj22djdw

Article title: Scientists investigate recent Philippine landslide
Authors: Alfredo Mahar Lagmay, John Ong, John Ong, Mark R. Lapus
Publication title: EOS 87(12), March 2006

Abstract:
A massive landslide devastated the community of Barangay Guinsaugon, Municipality of St. Bernard, Southern Leyte Province, Philippines, at about 10:30 local time on 17 February The landslide occurred along the steep fault scarp of the Philippine Fault Zone (PFZ) (Figure 1a), a large and active tectonic structure that traverses the entire length of the Philippines [Allen, 1962]. Barangay Guinsaugon is located at the foot of the scarp, directly in the path of the downward moving mass of earth. As of 24 February the landslide caused 122 confirmed deaths; 1,328 people still are missing.
Full text link https://tinyurl.com/2usy769r

Article title: Estimating SiO 2 content of lava deposits in the humid tropics using remotely sensed imagery
Authors: Cielo F. Bastero and Alfredo Mahar Lagmay
Publication title: Journal of Volcanology and Geothermal Research 151(4):357-364, March 2006

Abstract:
Remote sensing methods used to determine the rheology and SiO2 composition of lava flows on Mars were utilized to estimate the composition of lava deposits in the Philippines. Test cases were conducted on two lava domes and two lava flow deposits to determine whether remote sensing methods can be applied as a rapid and economical means to assess hazards associated with volcanoes in the humid tropics. Our study shows that dimensional parameters derived from digital elevation models (DEMs) generated from airborne sensors are effective in determining the SiO2 content of lava deposits. The SiO2 values computed from the rheological properties of lava are found to be comparable to geochemically analyzed field samples. These results suggest that remote sensing methods to estimate the composition of lava deposits is viable and can serve as a potentially useful tool for rapid and economic hazards assessment of volcanoes in tropical regions. With the growing number of high-resolution satellite sensors that routinely image the Earth's surface, such a technique can be widely utilized.
Full text available upon request to the author

Article title: Effects of Basement, Structure, and Stratigraphic Heritages on Volcano Behavior
Authors: Alfredo Mahar Lagmay
Publication title: Eos Transactions American Geophysical Union 87(23), January 2006

Abstract:
Effective natural hazard mitigation requires that the science surrounding geophysical events be thoroughly explored. With millions of people living on the flanks of volcanoes, understanding the parameters that effect volcanic behavior is critically important. In particular, basements can influence the occurrence of volcanic eruptions and landslides. This control by the substrate on volcano behavior usually has been considered questionable or less important than the conditions of the deep magma source. However, due to recent findings, this view is changing, specifically with regard to approaches in assessing volcanic hazards. The November 2005 AGU Chapman Conference ``Effects of Basement, Structure, and Stratigraphic Heritages on Volcano Behavior'' brought together geologists and geophysicists from North and South America, Europe, and Asia to discuss the results of their research on the reciprocal effects of the interaction between volcanos and their basements. The conference also highlighted the importance of holding Chapman conferences in developing countries such as the Philippines because many hazardous volcanos are situated in these countries. Apart from having natural field laboratories, these are the very same places that need to promote scientific discourse on volcano research, which can lead to more effective hazard mitigation programs.
Full text link https://tinyurl.com/j4t352ne

Article title: Effects of basement structural and stratigraphic heritages on volcano behaviour and implications for human activities (the UNESCO/IUGS/IGCP project 455)
Authors: Alessandro Tibaldi and Alfredo Mahar Lagmay
Publication title: Episodes 28(3), September 2005

Abstract:
UNESCO/IUGS/IGCP project 455 (2001-2005) is intended to contribute to the comprehension of volcano behaviour in different geodynamic settings from a poorly known perspective: the reciprocal influence exerted by volcanoes on their substrate and by the base-ment on the volcanoes. The main task is to assess the role of this influence in determining natural geological hazards such as eruptions, landslides and earthquakes. The geologic-tectonic control of the substrate on the volcanoes has been usually considered questionable or less important than the conditions of the deep magma source, whereas the control of volcanoes on their base-ment has even received very little attention. This project improves the comprehension of these phenomena by a strong interdisciplinary approach that ties data on the various geological conditions and heritages of the base-ment with the deformation processes and geological evolution of different volcanic edifices. We compiled stratigraphic, structural, geomorphological, geophysi-cal, geotechnical, petrographic, geochemical and geochronological data. These data have been trans-ferred to the laboratory-working groups, thus providing realistic numerical and physical simulation even of complex geological structures. Here we present a selec-tion of the main results obtained for some of the studied key volcanoes: Alicudi (Italy) located in a low-tectonic rate setting, Stromboli (Italy) in extensional tectonic setting, Reventador (Ecuador) in compressional setting, and the Northern Volcanic Group of Kamchatka (Rus-sia), Galeras (Colombia) and Mayon (Philippines) in a transtensional setting.
Full text link: https://tinyurl.com/jzr7yy8a

Article title: Deformed symmetrical volcanoes
Authors: Gianluca Norini and Alfredo Mahar Lagmay
Publication title: Geology 33(7), July 2005

Abstract:
Analog modeling of volcanic cones traversed by strike-slip faulting was conducted, and the cones were analyzed for deformation characteristics. The study shows that symmetrical volcanoes that have undergone basal strike-slip offset may be deformed internally without manifesting any change in their conical shape. Volcanoes deformed by strike-slip faulting may already have well-developed fractures in their interior, yet still appear as a symmetrical cone, exhibiting concentric contours when viewed on a topographic map. Moreover, slight changes in the basal shape of the cone induced by strike-slip movement can be restored by the relatively faster resurfacing and reshaping processes from the deposition of younger eruptive products. These findings pose a subtle but significant point in the assessment of volcanic landslide hazards: not all perfect cones are undisturbed. The detection of concealed deformation is important because fractures induce further instability in volcanoes and act as slip planes during volcano-collapse events. There are many examples of symmetrical volcanoes in nature. The faultless appearance of such perfect cones can be misleading, which requires careful attention in hazards assessment.
Full text link: https://tinyurl.com/knassjw7

Article title: Structural setting of the Bicol Basin and kinematic analysis of fractures on Mayon Volcano, Philippines
Authors: Alfredo Mahar Lagmay, Arlene Tengonciang, H.S. Uy
Publication title: Journal of Volcanology and Geothermal Research 144(s 1–4):23–36, June 2005

Abstract:
Mayon Volcano is located within the Bicol Basin in the southeastern region of Luzon, Philippines. The basin is contained within a releasing bend associated with the curvature of the central segment of the left-lateral Philippine Fault. A structural analysis of the faults that traverse the Bicol Basin was conducted through reviews of existing literature, seismic data interpretation, and remote sensing; in particular, those structures that may have influenced the growth and evolution of Mayon. Dynamic analysis of the aforementioned structures reveals a regional transtensional stress regime for the Bicol Basin. Field investigation on Mayon's slopes revealed the existence of fractures along its western and eastern flanks. These structures on Mayon have the same geometry as the dominant faults found within the Bicol Basin. Interpretation of these fractures indicates a tectonic control over their origin. The identification of fractures on Mayon's slopes is the first description of such features on its edifice. These new data highlight the probable landslide hazards associated with an oversteepened volcano that may have been further destabilized by tectonic activity.
Full text link: https://tinyurl.com/s7wd7nbw

Article title: A structural model guide for geothermal exploration in Ancestral Mount Bao, Leyte, Philippines
Authors: Alfredo Mahar Lagmay, Arlene Tengonciang, Herbert V Marcos, Chelo Pascua
Publication title: Journal of Volcanology and Geothermal Research 122(s 1–2):133–141, March 2003

Abstract:
The Tongonan Geothermal Field is the largest producing geothermal field in the Philippines having an installed capacity of 700 MW. It hosts several major power plants that tap geothermal power from the northern flank of the eroded Ancestral Mount Bao (AMB) volcano in Leyte Island, Philippines. A structural model guide is presented to delineate exploration targets in other flanks of the 1200 km2 area of the AMB volcano. If applied, the model constrains the coverage of geothermal exploration to areas where more detailed investigations involving geological, geophysical, and geochemical methods can be conducted. Analog sand cone experiments and their comparison with the deformation of the AMB volcano were used to interpret wells within the Tongonan Geothermal Field. The study shows that existing producing wells in Tongonan straddle the crypto-Philippine fault, a N34°W (azimuth=326°) trending master fault inferred to traverse the base of the AMB volcano. This master fault induced fracture-controlled permeability where fluids in the Tongonan Geothermal Field circulate. The structural model suggests that the south-southeastern flank of the AMB directly above the southern extension of the master Philippine fault is an ideal geothermal target amenable to detailed exploration.
Full text link https://tinyurl.com/2fvjn9xm

Article title: Volcano instability induced by strike-slip faulting
Authors: Alfredo Mahar Lagmay, Benjamin van Wyk de Vries, Norman Kerle, David M Pyle
Publication title: Bulletin of Volcanology 62(4):331-346, November 2000

Abstract:
Analogue sand cone experiments were conducted to study instability generated on volcanic cones by basal strike-slip movement. The results of the analogue models demonstrate that edifice instability may be generated when strike-slip faults underlying a volcano move as a result of tectonic adjustment. This instability occurs on flanks of the volcano above the strike-slip shear. On the surface of the volcano this appears as a pair of sigmoids composed of one reverse and one normal fault. In the interior of the cone the faults form a flower structure. Two destabilised regions are created on the cone flanks between the traces of the sigmoidal faults. Bulging, intense fracturing and landsliding characterise these unstable flanks. Additional analogue experiments conducted to model magmatic intrusion show that fractures and faults developed within the volcanic cone due to basal strike-slip motions strongly control the path of the intruding magma. Intrusion is diverted towards the areas where previous development of reverse and normal faults have occurred, thus causing further instability. We compare our model results to two examples of volcanoes on strike-slip faults: Iriga volcano (Philippines), which underwent non-magmatic collapse, and Mount St. Helens (USA), where a cryptodome was emplaced prior to failure. In the analogue and natural examples, the direction of collapse takes place roughly parallel to the orientation of the underlying shear. The model presented proposes one mechanism for strike-parallel breaching of volcanoes, recently recognised as a common failure direction of volcanoes found in regions with transcurrent and transtensional deformation. The recognition of the effect of basal shearing on volcano stability enables prediction of the likely direction of eventual flank failure in volcanoes overlying strike-slip faults.
Full text available upon request to the author

Article title: Control of crater morphology on flow path direction of Soufriere-type pyroclastic flows
Authors: Alfredo Mahar Lagmay, David M. Pyle, Brynee Dade, Clive Oppenheimer
Publication title: Journal of Geophysical Research Atmospheres 104(B4):7169-7181, April 1999

Abstract:
We present a model of fountain collapse for small-scale (Soufrière-type) explosive eruptions that relates the asymmetry of a volcanic crater (e.g., the presence of crater notches) with the emplacement direction of pyroclastic flows. Analysis of two-dimensional simulations of compressible fluids emanating from asymmetric nozzles shows that under sonic to supersonic conditions, the streamline of a jet can become tilted. The inclination of the streamline increases with greater slant angle of the nozzle and with increasing exit pressure. Using the two-dimensional simulations as analogues to volcanic eruptions, we propose that pyroclastic ejecta within the inner core of an erupting jet column can become asymmetrically focused before collapsing at fountain heights of a few hundred meters above the crater exit. The ensuing pyroclastic flows associated with fountain collapse thus become directional in character with flow orientation controlled by crater geometry and eruption exit pressure. The model applies to volcanoes with vertical conduits and crater to vent geometries that act as effective sonic to supersonic jet nozzles. We propose that the 1984 eruption of Mayon volcano fits this model. In the second phase of this eruption a prominent crater notch imparted a southeastward tilt to the basal gas thrust region of the eruption column. In turn, this led to the discharge of pyroclastic flows onto the southeast flank of the volcano.
Full text link: https://tinyurl.com/79tcn9uk