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Philippine Institute of Volcanology and Seismology
Philippine Institute of Volcanology and Seismology
Philippine Institute of Volcanology and Seismology
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Philippine Institute of Volcanology and Seismology
Surian ng Pilipinas sa Bulkanolohiya at Sismolohiya
Map
Agency overview
FormedSeptember 17, 1982
(43 years ago) (1982-09-17)
Preceding agencies
  • Commission on Volcanology (COMVOL)
  • Philippine Institute of Volcanology (PHIVOLC)
JurisdictionPhilippines
HeadquartersC.P. Garcia Avenue, UP Campus, Diliman, Quezon City
14°39′6.94″N 121°3′30.68″E / 14.6519278°N 121.0585222°E / 14.6519278; 121.0585222
Employees208 (2024)[1]
Annual budget₱529.18 million (2021)[2]
Agency executive
  • Usec. Teresito C. Bacolcol, Director
Parent agencyDepartment of Science and Technology
Websitewww.phivolcs.dost.gov.ph
PHIVOLCS Observatory at Mount Hibok-Hibok.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS, Filipino: [ˈfivolks]; Filipino: Surian ng Pilipinas sa Bulkanolohiya at Sismolohiya[3]) is a Philippine national institution dedicated to provide information on the activities of volcanoes, earthquakes, and tsunamis, as well as other specialized information and services primarily for the protection of life and property and in support of economic, productivity, and sustainable development. It is one of the service agencies of the Department of Science and Technology.

PHIVOLCS monitors volcano, earthquake, and tsunami activity, and issues warnings as necessary. It is mandated to mitigate disasters that may arise from such volcanic eruptions, earthquakes, tsunamis, and other related geotectonic phenomena.[4]

History

[edit]

This government organization was formed after a historical merging of official functions of government institutions.

One of its first predecessors is the Philippine Weather Bureau created in 1901[5] when meteorological, seismological and terrestrial magnetic services of the Manila Observatory were transferred from the Roman Catholic Church to the American Colonial Government. It performed earthquake monitoring in the country and has inherited and maintained the early earthquake catalogue at that time. By 1972, the Philippine Weather Bureau was reorganized under Presidential Decree No. 78[6] into the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA). A United Nations Development Programme-funded project for PAGASA established a twelve-station earthquake monitoring network in the country.

In February 1951, Dr. Jose M. Feliciano, Chair of the Division of Physical and Mathematical Sciences of the National Research Council of the Philippines (NRCP) presented a proposal for the creation of a Commission on Volcanology. The eruption of Mount Hibok-Hibok in December 1951 and the consequent destruction and loss of lives led to the closer cooperation by the Geology, Seismology, and Volcanology Section, committee on Volcanology of the Department of Agriculture and Natural Resources, to study volcanoes in the Philippines.[7] This collaboration let to the enactment of Republic Act No. 766[8] on June 20, 1952 that created the Commission of Volcanology (COMVOL). This Commission was placed under NRCP and its office was initially set up in the College of Liberal Arts in UP Diliman.[7] Under Executive Order No. 784 of March 17, 1982, the umbrella department of COMVOL, the National Science Development Board (NSDB) was reorganized into the National Science and Technology Authority (NSTA), and COMVOL was restructured to become the Philippine Institute of Volcanology or PHIVOLC.[9]

The seismological arm of PAGASA was officially transferred to PHIVOLC[10] on September 17, 1984 through Executive Order No. 984, renaming the institute as the Philippines Institute of Volcanology and Seismology or PHIVOLCS.[11] The NSTA, the umbrella department for PHIVOLCS and PAGASA, became the Department of Science and Technology (DOST) in 1987. The technical staff and the 12-station earthquake monitoring network was fully integrated to PHIVOLCS in 1988.

PHILVOCS and the United States Geological Survey collaborated during the 1991 eruption of Mount Pinatubo. Their forecast provided the timely evacuation of military personnel and residents that were affected by the eruption.[12]

PHIVOLCS was headed by Raymundo Punongbayan from 1982 to 2002,[13] and it is currently headed by Renato U. Solidum Jr. from 2003 to the 2023.

Dr. Teresito C. Bacolcol was appointed as the new Director and took his oath on January 23, 2023, with Science and Technology Secretary Dr. Renato U. Solidum, Jr. in Quezon City.[14]

In April 2025, President Bongbong Marcos signed a law measure modernizing the Philippine Institute of Volcanology and Seismology (PHIVOLCS) to improve its technological operational capacity.[15][16]

Classification of volcanoes in the Philippines

[edit]
In 1984, pyroclastic flows descend the south-eastern flank of Mayon Volcano, the most active volcano in the Philippines

PHIVOLCS classifies volcanoes as active, potentially active, or inactive:[17]

Active

[edit]
Main article: List of active volcanoes in the Philippines
Mt. Isarog, a potentially active volcano in the Phillppines

Potentially active

[edit]
Mt. Arayat, a potentially active volcano in the Philippines.
Main article: List of potentially active volcanoes in the Philippines
  • Active solfataras, fumaroles, or steaming activity
  • Geologically young, possibly erupted < 10,000 years and for calderas and large systems, possibly < 25,000 years.
  • Young-looking geomorphology (thin soil cover or sparse vegetation; low degree of erosion and dissection; young vent features; with or without vegetation cover).
  • Suspected seismic activity.
  • Documented local ground deformation.
  • Geochemical indicators of magmatic involvement.
  • Geophysical proof of magma bodies.
  • Strong connection with subduction zones and external tectonic settings.

Inactive

[edit]
Main article: List of inactive volcanoes in the Philippines
  • No record of eruption and its form is beginning to change by the agents of weathering and erosion via formation of deep and long gullies.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Philippine Institute of Volcanology and Seismology

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The Philippine Institute of Volcanology and Seismology (PHIVOLCS) (Filipino: Surian ng Pilipinas sa Bulkanolohiya at Sismolohiya) is a specialized government agency under the Department of Science and Technology (DOST) in the Philippines, dedicated to monitoring volcanic activity, earthquakes, tsunamis, and related geotectonic phenomena to mitigate associated disaster risks. Established in response to the devastating 1951 eruption of Mount Hibok-Hibok, PHIVOLCS evolved from the Commission on Volcanology (COMVOL), founded on June 20, 1952, through Republic Act No. 766, with the primary aim of safeguarding lives and property from volcanic hazards. Over the decades, it has expanded its scope to encompass seismology and tsunami monitoring, reflecting the archipelago's position along the Pacific Ring of Fire, where it operates a network of observatories, seismic stations, and laboratories to provide real-time data and early warnings. PHIVOLCS's history traces a path of institutional reorganization to address growing geological threats. Initially placed under the National Research Council of the Philippines, COMVOL was transferred to the National Science Development Board before being restructured as the Philippine Institute of (PHIVOLC) on March 17, 1982, via No. 784, under the National Science and Technology Authority (NSTA). In 1984, seismological functions were integrated from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (), leading to its renaming as PHIVOLCS on September 17 of that year. The agency achieved its current form on January 30, 1987, when the NSTA was elevated to the full-fledged DOST through No. 128, embedding PHIVOLCS as a key service institute for . Headquartered at the PHIVOLCS Building in , , it continues to advance through initiatives like the 2025 PHIVOLCS Modernization Act (Republic Act No. 12180), which allocates resources for upgraded equipment, expanded seismic networks, and enhanced personnel training to bolster national resilience. Under its mandate, PHIVOLCS is principally tasked with predicting and assessing the impacts of volcanic eruptions, s, and tsunamis, while disseminating accurate information to support public preparedness and government response. Its core functions include continuous via advanced , hazard mapping through tools like HazardHunterPH and GeoRiskPH platforms, and public programs, such as drills and volcano awareness campaigns. The agency issues alerts, conducts research on tectonic hazards, and collaborates internationally—such as with the —to improve forecasting accuracy, playing a pivotal role in events like the 1991 eruption monitoring, the response to the September 30, 2025, magnitude 6.9 , and ongoing responses to seismic activity in the region. Through these efforts, PHIVOLCS not only saves lives but also contributes to by integrating science into policy for a disaster-resilient .

History

Establishment

The devastating eruption of on Island in 1951, which killed over 3,000 people and caused widespread destruction, underscored the urgent need for systematic volcano monitoring in the . This catastrophic event, involving pyroclastic flows and lahars that devastated communities and reduced the island's population significantly, prompted national recognition of the country's vulnerability to volcanic hazards. In response, the Philippine government established the Commission on (COMVOL) on June 20, 1952, through Republic Act No. 766, marking the creation of the first dedicated government body for . Initially placed under the Executive Board of the National Research Council of the , COMVOL was tasked with investigating volcanic activities, predicting eruptions, and providing relief to affected areas. COMVOL's early objectives centered on safeguarding life and property through comprehensive volcano surveillance, research, and public warnings, with an initial emphasis on post-eruption studies and establishing basic observation networks across active volcanoes. These efforts included geological surveys and the installation of rudimentary monitoring stations to gather data on seismic and fumarolic activity, laying the groundwork for hazard mitigation in a seismically active archipelago. During the 1960s, COMVOL was transferred to the National Science Development Board (NSDB) to enhance coordination with broader scientific initiatives and expand its research capabilities. This shift facilitated greater integration of volcanological studies with national science policy, though subsequent restructurings in the 1980s would evolve COMVOL into the modern Philippine Institute of Volcanology and Seismology.

Key Milestones and Restructurings

The Commission on Volcanology (COMVOL), established in 1952 as a precursor agency, underwent significant reorganization on March 17, 1982, through Executive Order No. 784, which restructured it into the Philippine Institute of Volcanology (PHIVOLC) under the newly formed National Science and Technology Authority (NSTA) to bolster research and operational capabilities in . On September 17, 1984, seismological functions were transferred from the to PHIVOLC via No. 984, which also relocated PAGASA to NSTA; this integration expanded the institute's scope to encompass comprehensive geotectonic hazard monitoring and led to its renaming as the Philippine Institute of Volcanology and Seismology (PHIVOLCS). Further institutional evolution occurred on January 30, 1987, when No. 128 reorganized NSTA into the Department of Science and Technology (DOST), placing PHIVOLCS under DOST as an attached agency and granting it an expanded mandate for disaster risk mitigation, including enhanced coordination for volcanic, seismic, and tsunami hazards. In the post-1987 period, PHIVOLCS advanced its capabilities through key developments, such as the formulation of national monitoring standards in the following the 1991 eruption, which prompted the installation of new seismic and monitoring instruments and the establishment of improved hazard assessment protocols in collaboration with international partners like the U.S. Geological Survey. During the 2000s, the agency implemented digital upgrades to its seismic network, including the transition from analog to systems starting in 2000, enabling real-time data transmission and more accurate detection across the archipelago. In April 2025, Republic Act No. 12180, known as the PHIVOLCS Modernization Act, was signed into , allocating P7 billion for upgraded equipment, expanded seismic networks, enhanced personnel training, and other initiatives to bolster the agency's capacity for .

Mandate and Objectives

Vision and Mission

The Philippine Institute of and (PHIVOLCS) articulates its vision as a leading global science and technology institution of empowered men and women helping develop communities safe from and resilient to volcanic eruptions, earthquakes, tsunamis, and other related hazards. This aspirational statement underscores PHIVOLCS's commitment to fostering resilience in the , a seismically active prone to multiple natural hazards, through empowered personnel and advanced scientific capabilities. PHIVOLCS's mission is to provide timely, quality, and socially-inclusive information and services for warning, disaster preparedness, and , achieved through the development and application of technologies for monitoring, accurate , and identification of hazard-prone areas, alongside gender-responsive capacity enhancement for comprehensive . This mission aligns with the broader goals of its parent agency, the Department of Science and Technology (DOST), which emphasizes science-based approaches to in vulnerable regions. The emphasis on social inclusivity and gender-responsive strategies ensures that hazard communication and community empowerment efforts address diverse needs, promoting equitable access to vital information. These guiding principles inform PHIVOLCS's overall approach to hazard monitoring, ensuring that scientific outputs contribute directly to community safety and national resilience.

Primary Functions

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) is principally mandated to predict the occurrence of volcanic eruptions, earthquakes, tsunamis, and related geotectonic phenomena through advanced and modeling techniques. This core function involves assessing how these events may unfold, identifying likely affected areas, and evaluating potential impacts using forecasting systems developed from continuous monitoring and scientific research. By generating sufficient data on seismic and volcanic activities, PHIVOLCS enables accurate predictions that safeguard communities in a tectonically active region like the . In parallel, PHIVOLCS focuses on hazard mitigation by establishing detection networks, issuing timely warnings, and developing plans to minimize loss of life and property. These efforts include formulating strategies for immediate response, such as evacuation guidelines during elevated alert levels, ensuring that warnings reach vulnerable populations effectively. Through these mechanisms, the institute reduces the risks posed by sudden geophysical events, promoting resilience across urban and rural areas. PHIVOLCS also generates comprehensive scientific data for long-term , encompassing geotectonic studies that inform public advisories and policy decisions. This includes mapping hazard zones and providing evidence-based recommendations for . To enhance these outcomes, PHIVOLCS collaborates with local governments and stakeholders to integrate hazard assessments into evacuation protocols and , fostering coordinated at the community level.

Organizational Structure

Leadership and Governance

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) operates as an attached agency of the Department of Science and Technology (DOST), ensuring policy coordination and program implementation in line with national science and technology priorities. This governance framework positions PHIVOLCS under the oversight of the DOST Secretary, who provides strategic direction for efforts related to volcanic, seismic, and tsunami hazards. At the helm of PHIVOLCS is the , a position equivalent in rank to a Department Undersecretary, who holds ultimate responsibility for the institute's overall operations, policy execution, and representation in national and international forums on geohazards. As of November 2025, Dr. Teresito C. Bacolcol serves as , leading initiatives such as the modernization program and collaborating with global partners on hazard monitoring technologies. The is supported by three Deputy Executive Directors, each holding the rank of and overseeing key areas: operations, and development/science and technology, and administration//. The appointment of the and Deputy Executive Directors is conducted by the upon the recommendation of the DOST Secretary, requiring candidates to be natural-born citizens with advanced degrees in relevant fields, at least five years of expertise in , , or allied disciplines, and eligibility as Career Executive Service Officers. These terms are typically aligned with governmental administrative cycles, ensuring continuity in leadership amid policy shifts. Key governance mechanisms at PHIVOLCS include its Quality Policy Statement, which commits the institute to delivering timely, high-quality, and socially inclusive information and services for and management of earthquakes, tsunamis, volcanoes, and related hazards. Strategic planning is integrated with the National Disaster Risk Reduction and Management Plan (NDRRMP) 2020-2030, focusing on enhancing monitoring capabilities, forecasting accuracy, and public preparedness to minimize disaster impacts nationwide. Under the PHIVOLCS Modernization Act of 2025 (Republic Act No. 12180), the formulates and oversees a five-year modernization program, funded by a P7 billion allocation, to bolster infrastructure and technical capacity in alignment with these national objectives.

Divisions and Departments

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) operates through specialized divisions that oversee core scientific, technical, and administrative functions, all reporting directly to the institute's Director. These units ensure coordinated efforts in monitoring, , , and support to fulfill PHIVOLCS's mandate in . The Volcano Monitoring and Eruption Prediction Division (VMEPD) handles real-time surveillance of active es across the , collecting and analyzing geophysical, geodetic, and geochemical data to forecast eruptive activity and assign appropriate alert levels for public safety. This division issues certifications on volcano status and provides data through portals like the Local Active Volcanoes Archive-Dynamic Operational Monitoring Environment (LAVA-DOME) to support and emergency response. The Seismological Observation and Earthquake Prediction Division (SOEPD) is tasked with detecting and recording seismic events nationwide, maintaining earthquake catalogs, and generating seismicity maps that detail epicenters, magnitudes, and depths. It also develops probabilistic and deterministic ground shaking hazard maps to inform building codes, risk assessments, and tsunami evaluations, ensuring timely dissemination of earthquake information for mitigation. The Geology and Geophysics Research and Development Division (GGRDD) conducts in-depth geological mapping and geophysical studies to model hazards from tectonic and volcanic sources, producing site-specific assessments for land use planning and infrastructure resilience. Through tools like the Hazard Assessment Service and GeoRiskPH platform, it delivers reports on earthquake-induced risks and volcanic threats, integrating GIS data for comprehensive hazard evaluation. The Geologic Disaster Awareness and Preparedness Division (GDAPD) leads outreach and education initiatives on volcanoes, earthquakes, and s, developing informational materials, conducting lectures, and facilitating community drills to build public resilience. It coordinates specialized warnings and preparedness programs, including tsunami awareness campaigns, to enhance local response capabilities and integrate geologic risks into disaster management strategies. The Finance and Administrative Division (FAD) manages the institute's financial resources, , processes, and overall , ensuring efficient support for all operational and activities across PHIVOLCS.

Monitoring and Research Activities

Volcanic Monitoring

The Philippine Institute of and (PHIVOLCS) employs a comprehensive network of multi-parameter instruments to monitor volcanic activity across the . Seismometers are deployed to detect and record volcanic earthquakes, which indicate movement or pressure changes beneath the surface. (GPS) receivers and tiltmeters track ground deformation and subtle tilting of the Earth's surface, respectively, providing early signs of intrusion or pressure buildup. Gas sensors, including scanning Differential Optical Absorption Spectroscopy (SCAN-DOAS) systems and CO2 sensors, measure emissions of (SO2) and (CO2) from volcanic vents, helping to assess rates and potential eruption triggers. These instruments form the backbone of PHIVOLCS's protocols for observing and predicting volcanic unrest, with data transmitted in real-time to central hubs for immediate evaluation. The alert level system, ranging from 0 to 5, is based on integrated unrest indicators such as increased seismic activity, elevated gas emissions, ground swelling, and thermal changes. Level 1 signifies low-level unrest with abnormal activity like minor earthquakes or steam emissions, while Level 5 indicates a hazardous eruption in progress, characterized by explosive events, pyroclastic flows, and widespread ashfall. This tiered system guides public safety measures and evacuation decisions, with step-down criteria requiring sustained decreases in activity over periods from 24 hours to several weeks. PHIVOLCS conducts routine surveillance of its 24 classified active volcanoes, combining instrumental data with visual observations from ground-based personnel and webcams to monitor steam plumes, ejections, and crater glow. Satellite data integration, including (InSAR) imagery, supplements on-site monitoring by detecting broad-scale deformation and thermal anomalies not visible from ground instruments. These methods ensure continuous assessment, with daily bulletins issued to report any changes in volcanic behavior. In addition to operational monitoring, PHIVOLCS advances research on eruption forecasting models that incorporate historical data from major events, such as the 1991 eruption. Techniques like the Materials Failure Forecast Method (FFM) and Stochastic Seismic Amplitude Measurement (SSAM) analyze precursory seismic patterns to predict eruption timing, drawing lessons from Pinatubo's pre-eruptive unrest involving thousands of earthquakes and rapid deformation. Multiscale fracture models further refine predictions by simulating ascent based on observed seismic and deformation data. These research efforts enhance the accuracy of forecasts for future volcanic crises.

Seismic and Tsunami Monitoring

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) operates the Philippine Seismic Network (PSN), a nationwide system comprising approximately 125 seismic stations designed to detect and characterize earthquakes in real time. These stations, including about 29 manned facilities and numerous satellite-telemetered unmanned ones, record seismic waves using broadband seismometers and short-period instruments, allowing for the precise of epicenters through standard methods based on the arrival times of primary () and secondary (S) waves at multiple sites. Magnitudes are determined using the local magnitude scale (ML), commonly referred to as the in public communications, which quantifies the amplitude of ground motion recorded by seismographs. Intensities, which describe the effects of shaking on people, structures, and the environment, are assessed via the PHIVOLCS Earthquake Intensity Scale (PEIS), a 10-level modified Mercalli scale that incorporates both instrumental data from strong-motion sensors and reports from affected areas. Complementing the PSN, PHIVOLCS maintains the Philippine Strong Motion Network (PSMNet), which includes over 100 strong-motion accelerographs strategically placed in high-risk urban and coastal areas to capture peak ground accelerations during moderate to strong . This network provides essential engineering data for seismic design standards, particularly in tectonically active regions dominated by zones along the and strike-slip faults like the Philippine Fault, where the majority of seismic events originate. Data from both networks are processed 24/7 at the central Data Receiving Center in , enabling the rapid generation of earthquake bulletins—often within 5 to 10 minutes of an event—with details on , depth, magnitude, and potential impacts. For tsunami monitoring, PHIVOLCS implements the Tsunami Early Warning System (TEWS), which integrates seismic alerts with observations from a distributed array of coastal sea-level gauges, including water-level sensors and tide stations such as the six operational units in the Visayas region for local detection. The system distinguishes between local tsunamis, generated by nearby earthquakes in subduction zones and requiring warnings within minutes based on rapid magnitude and fault modeling, and distant tsunamis from regional sources like the Pacific Ring of Fire, where propagation models predict arrival times (typically 1 to 24 hours) and expected wave amplitudes using numerical simulations. Confirmed sea-level disturbances trigger tsunami advisories or warnings disseminated via multiple channels, including SMS, social media, and local sirens, in accordance with standardized protocols to minimize false alarms while ensuring timely evacuations.

Volcano Classification System

Active Volcanoes

The Philippine Institute of and (PHIVOLCS) classifies a as active if it has erupted within historical times (the last 600 years) or shows of eruptions within the (the last 10,000 years) based on analysis of volcanic deposits. This classification is part of PHIVOLCS's broader categorization system, which also includes potentially active and inactive volcanoes based on eruptive history and geological . The criteria emphasize historical eruption records, ongoing signs of unrest such as seismic activity or gas emissions, and assessed potential for future eruptions, prioritizing those posing immediate hazards to nearby populations. As of the latest PHIVOLCS assessments (2018), with no major changes reported as of 2025, PHIVOLCS identifies 23 active volcanoes across the , distributed mainly along volcanic formed by tectonic plate interactions. These include both stratovolcanoes and calderas, with monitoring focused on those showing recent activity. The following table lists them alphabetically, along with their primary locations:
Volcano NameLocation (Region/Province)
Babuyan Claro (Luzon)
BanahawLaguna and (Luzon)
Biliran (Anas) ()
Bud Dajo ()
Bulusan (Luzon)
Cabalian ()
Cagua (Luzon)
Camiguin de Babuyanes, (Luzon)
Didicas, (Luzon)
Hibok-Hibok ()
IrayaBatan Islands, (Luzon)
Iriga (Luzon)
Kanlaon ()
Leonard Kniaseff ()
Makaturing ()
Matutum ()
Mayon (Luzon)
Musuan (Calayo) ()
Parker ()
Pinatubo, , (Luzon)
Ragang and ()
Smith, (Luzon)
TaalBatangas (Luzon)
Source: Compiled from PHIVOLCS official records. Among these, Mayon Volcano stands out as the most active, with over 50 documented eruptions since 1616, including frequent Strombolian and Vulcanian events that have shaped its iconic symmetrical cone. has recorded approximately 33 eruptions since the 16th century, with its most recent significant phreatomagmatic activity in January 2020, which produced ash plumes and forced evacuations from its lake island. Mount Pinatubo's 1991 eruption marked its return to historical activity after centuries of dormancy, releasing a massive ash column equivalent to a (VEI) of 6 and causing global climatic effects through . PHIVOLCS prioritizes monitoring of these active volcanoes through continuous seismic, gas, and deformation networks, establishing permanent danger zones (PDZs) around their summits—typically 6 to 10 kilometers in radius—to restrict access and mitigate risks from sudden eruptions, pyroclastic flows, or lahars. For instance, entry into Mayon's 6-km PDZ is prohibited during unrest to protect communities in Province.

Potentially Active Volcanoes

Potentially active volcanoes in the are defined as those exhibiting morphologically young features, such as intact craters or recent lava flows, indicating possible eruptions within the last 10,000 years ( epoch), but lacking any historical or analytical records of eruptions. This emphasizes geological evidence of youth over documented historical activity, distinguishing them from volcanoes with confirmed eruptions in the last 600 years. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) identifies approximately 22 such volcanoes, assessed through field surveys and of volcanic deposits to confirm activity. Representative examples include in and in , where young deposits suggest prehistoric eruptions without human records. These volcanoes receive lower monitoring priority compared to active ones, as they lack current unrest indicators requiring real-time surveillance, yet PHIVOLCS incorporates them into national hazard maps to delineate risks from potential lahars, lava flows, and pyroclastic events. In contrast to inactive volcanoes, which display heavily eroded forms with no evidence of eruptions in the or later, potentially active ones retain fresh geological signatures warranting preparedness measures.

Inactive Volcanoes

Inactive volcanoes, as classified by the Philippine Institute of Volcanology and Seismology (PHIVOLCS), are those with no record of eruptions and whose physical forms have been significantly altered by and , resulting in deep gullies and no recent volcanic deposits. This dormancy typically exceeds 10,000 years, corresponding to the epoch, during which no magmatic or eruptive activity is evident through geological evidence. As of the latest PHIVOLCS assessments (2018), with no major changes reported as of 2025, PHIVOLCS has mapped approximately 300 inactive volcanoes nationwide through comprehensive geological surveys, including examples such as in Zamboanga Peninsula and certain eroded volcanic edifices within the Macolod Corridor on . These identifications rely on field mapping and analysis to distinguish them from more recent formations. Given their prolonged inactivity, these volcanoes undergo minimal routine monitoring by PHIVOLCS, focusing instead on broader seismic networks rather than dedicated observatories. Nonetheless, they are evaluated for long-term reactivation potential in assessments, acknowledging that tectonic processes in the could theoretically reawaken such features after millennia. The criteria emphasize the age of the last eruption, determined via stratigraphic methods that sequence rock layers and techniques, such as radiocarbon analysis for organic materials or potassium-argon dating for older rocks, confirming no activity within the past 10,000 years. These approaches ensure precise differentiation from potentially active volcanoes, prioritizing evidence-based risk evaluation over morphological appearance alone.

Facilities and Infrastructure

Headquarters and Observatories

The central headquarters of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) is located at the PHIVOLCS Building on C.P. Garcia Avenue, campus, , 1101. This facility serves as the primary hub for administrative operations, , and scientific research, housing specialized laboratories for geochemical and geophysical analysis as well as the main data receiving center that integrates nationwide monitoring inputs. PHIVOLCS maintains several regional observatories to ensure localized oversight of volcanic activity across the . The Bicol Volcano Observatory, encompassing facilities for monitoring Mayon and Bulusan volcanoes, includes the Mayon Volcano Observatory at Ligñon Hill, Legazpi City, , and the Bulusan Volcano Observatory in Barangay Cabid-an, . These sites support on-site staffing by resident volcanologists and technicians, routine maintenance of monitoring equipment, and coordination with units and communities for timely hazard communication and response preparedness. In the southern regions, the Southern Volcano Observatory covers key sites such as the Kanlaon Volcano Observatory, with outposts at La Carlota City College, Cubay Campus, La Carlota City, , and Barangay Pula, Canlaon City, , alongside the Hibok-Hibok Volcano Observatory in , . These observatories facilitate continuous local presence through dedicated personnel for equipment upkeep and foster collaboration with regional stakeholders to enhance volcanic risk mitigation. The Northern Luzon Observatory oversees activities in the northern part of the island, including stations near Taal and Pinatubo volcanoes, such as the Buco Observatory on the northern shore of in , performing similar functions of staffing, maintenance, and community engagement. A notable recent development is the inauguration of the Mindanao Cluster Monitoring Center in 2021, located at the Philippine Science High School–Southern Mindanao Campus in Mintal, . This facility bolsters southern coverage by providing a backup data processing site and managing regional monitoring stations, staffed by PHIVOLCS personnel to support equipment operations and local coordination efforts.

Monitoring Networks

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) maintains a comprehensive seismic network consisting of approximately 125 stations across the country as of 2025, to ensure nationwide coverage of activity. These stations are equipped with seismometers capable of detecting a wide range of seismic frequencies, from local tremors to distant teleseismic events, enabling precise location and magnitude determination. Under the PHIVOLCS Modernization Act (Republic Act No. 12180), enacted in 2025, the agency is expanding its seismic network toward 300 stations and upgrading facilities with state-of-the-art equipment to enhance detection and response capabilities. For volcanic monitoring, PHIVOLCS deploys multi-parameter instrument arrays at key volcanic sites, incorporating tiltmeters to measure ground deformation, spectrometers such as Differential Optical Absorption Spectroscopy (DOAS) systems for (SO₂) flux quantification, and thermal/infrared webcams for visual surveillance of plumes and craters. Data from these instruments are transmitted in real-time to central facilities via or satellite links, facilitating continuous assessment of volcanic unrest. The tsunami monitoring network operated by PHIVOLCS includes a series of coastal tide gauges and integration with offshore buoys, designed to detect anomalous sea-level changes and provide early warnings for local and distant . This system is interconnected with global networks, such as the (PTWC), allowing for coordinated alerts across the Pacific region through shared seismic and sea-level data feeds. In recent developments, PHIVOLCS introduced the VOLCAN mobile application in 2025, which streams live data including one-minute webcam snapshots and volcanic records to authorized users for enhanced remote monitoring. Complementing this, the HazardHunterPH platform offers public access to hazard susceptibility maps, integrating seismic, volcanic, and risk assessments for user-specified locations to promote community preparedness.

Notable Contributions and Events

Major Volcanic Eruption Responses

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) played a pivotal role in the response to the 1991 eruption, one of the largest volcanic events of the . In collaboration with the (USGS) through the Volcano Disaster Assistance Program, PHIVOLCS deployed monitoring equipment, including seismic stations and tiltmeters, to track the volcano's unrest starting in April 1991. This joint effort enabled the issuance of timely warnings, such as the level-3 alert on June 5, which prompted coordinated evacuations with local authorities and the U.S. military, relocating over 200,000 people from high-risk areas around and surrounding communities in the 20-40 km zone. These actions, including ashfall hazard maps and advisories, are credited with saving at least 5,000 lives, with total deaths around 800 (including indirect causes) despite the eruption's scale. During the 2020 Taal Volcano phreatomagmatic eruption, PHIVOLCS rapidly escalated the alert level to 4 on January 12, designating a 14 km permanent danger zone around the main crater and recommending immediate evacuations from Volcano Island and adjacent high-risk areas in Batangas and Cavite provinces. This led to the displacement of over 135,000 people in evacuation centers and an additional 170,000 outside, preventing widespread casualties from ashfall, steam plumes reaching 15 km, and ballistic projectiles. PHIVOLCS monitored volcanic smog (vog), a hazardous mix of sulfur dioxide (SO₂) emissions peaking at 5,299 tonnes per day, issuing advisories on its dispersion toward Metro Manila and nearby regions up to 100 km away. Post-eruption, the agency provided health guidelines, urging affected communities to conduct checks for respiratory issues, wear N95 masks outdoors, and stay indoors during vog episodes to mitigate SO₂ exposure risks. PHIVOLCS has consistently managed responses to Volcano's frequent eruptions, exemplified by the 2018 event characterized by lava flows advancing up to 3.5 km southeast toward the Mabinit channel. The agency enforced a 6 km permanent danger zone (PDZ) around the summit, expanding it to a precautionary 7-9 km extended danger zone (EDZ) to account for potential pyroclastic density currents and rockfalls. Additionally, PHIVOLCS issued warnings for active river channels and perennially prone areas across all sectors, advising avoidance of stream beds due to risks from rain-induced mudflows mobilizing loose deposits, which affected downstream communities in province. These measures ensured no entries into restricted zones and facilitated the safe relocation of residents during heightened unrest. Beyond specific crises, PHIVOLCS has contributed to global modeling through post-Pinatubo innovations, including the deployment of automated rain gauges and high-frequency acoustic flow monitors in collaboration with USGS, which informed hazard mapping and early warning systems adopted internationally for lahar-prone volcanoes. For , PHIVOLCS serves as a key provider of real-time data to the Volcanic Ash Advisory Center (VAAC) under ICAO protocols, issuing alerts on ash plume heights, dispersion, and trajectories—such as during Taal's 2020 emissions—to enable flight rerouting and prevent engine damage from abrasive particles.

Significant Earthquake and Tsunami Responses

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) played a pivotal role in responding to the magnitude 7.8 earthquake on July 16, 1990, which caused extensive damage across northern , including the collapse of buildings in Baguio City and widespread ground deformation. Immediately following the event, PHIVOLCS conducted rapid intensity mapping using a modified Rossi-Forel scale, documenting intensities up to VIII-IX in areas like Dagupan City, Baguio City, and , based on field observations of ground motion, , and structural failures. This mapping effort involved isoseismal analysis and collaboration with researchers to delineate affected zones, providing critical data for initial damage evaluation and emergency response coordination. PHIVOLCS also deployed temporary seismic stations around the zone to monitor ongoing activity, strategically placing them along the Philippine Fault-Digdig Fault system and near and . This monitoring revealed aftershocks tracing dual faulting sequences, with analyses from strong aftershocks indicating left-lateral strike-slip movement on the main fault and extensional faulting in the area. These fault studies contributed to enhanced assessments, informing geological constraints for and subsequent revisions to the National of the to improve structural resilience in fault-prone regions. In the magnitude 7.2 earthquake of October 15, 2013, which struck and caused over 200 deaths along with significant infrastructure damage, PHIVOLCS issued a tsunami advisory shortly after the event due to its offshore potential, though no significant waves were generated. The agency conducted comprehensive damage assessments, documenting ground ruptures with displacements up to 6 meters along the North Bohol Fault, uplift of coastlines in , , and limited in coastal areas. These assessments included monitoring, with over 2,100 events recorded in the initial weeks, 41 of which were felt, aiding in risk zoning and recovery planning for and provinces. PHIVOLCS's liquefaction research highlighted soil amplification effects in the region, leading to updated hazard maps that guided rehabilitation efforts and building retrofitting. The 1976 magnitude 8.0 Moro Gulf earthquake and ensuing , which devastated southwestern with waves up to 9 meters high and caused over 8,000 fatalities, underscored the need for dedicated seismic and monitoring in the . The predecessor Commission on (COMVOL) monitored aftershocks and conducted post-event analysis of the Cotabato Trench rupture and inundation patterns. These analyses drove improvements to early warning systems, including the integration of seismic networks for faster detection, and laid the foundation for national preparedness plans, such as community-based evacuation protocols and hazard mapping for Moro Gulf coastal areas. In response to the magnitude 6.9 Northern Cebu on September 30, 2025, which struck offshore near Bogo City with a shallow depth of 5 km, PHIVOLCS issued immediate intensity reports and advisories, confirming no significant waves. The agency rapidly deployed teams to map coseismic surface ruptures along the Bogo Bay Fault, documenting displacements and ground deformation using and field surveys. Over 100 aftershocks were recorded in the following weeks, aiding in hazard assessments and recovery coordination for affected areas in , with no reported casualties but damage to . Building on these historical responses, PHIVOLCS has advanced its capabilities with digital tools by 2025, including enhanced command centers for real-time coordination and apps like HazardHunterPH for public self-assessments of structural . These innovations enable faster alert dissemination through integrated seismic data from monitoring networks and support ongoing public education campaigns, such as webinars and DRR training for local governments, emphasizing preparedness in high-risk areas.

References

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