Global Volcanism Program

The Global Volcanism Program has no activity reports available for Iriga.

The Global Volcanism Program has no Weekly Reports available for Iriga.

The Global Volcanism Program has no Bulletin Reports available for Iriga.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Synonyms

Asog

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude

273041

Unknown - Evidence Credible

1,138 m / 3,734 ft

13.458°N
123.451°E

Morphology

Volcano Landform
Composite

Volcano Types
Stratovolcano
Pyroclastic cone(s)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km

3,712
142,254
1,159,509
4,399,866

Geological Summary

Mount Iriga (locally known as Mt Asog) is a small andesitic stratovolcano that rises immediately W of Lake Buhi which has satellitic cinder cones of basaltic composition. A large breached crater open to the SE was formed as a result of a major debris avalanche that buried several villages and formed a broad hummocky deposit across the plain south of Lake Buhi. This catastrophic event was at one time considered to have occurred during 1628 CE, but later work has shown that the collapse occurred earlier at some unknown date during the Holocene. An older debris avalanche deposit of similar size was also described SW of the volcano (Paguican et al., 2010). Both debris avalanche deposits cover wide areas of low, waterlogged plains, to a distance of ~16 km for the older and 12 km for the younger. The collapse orientation and deposit constituents for both are consistent with being a response to transtensional faulting and gravity spreading. A cone and lava covering about 9 km² post-date the younger collapse.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Aguila L G, Newhall C G, Miller C D, Listanco E L, 1986. Reconnaissance geology of a large debris avalanche from Iriga volcano, Philippines. Philippine J Volc, 3: 54-72.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior.

Paguican E M R, van Wyk de Vries B, Lagmay A M F, 2012. Volcano-tectonic controls and emplacement kinematics of the Iriga debris avalanches (Philippines). Bull Volcanol, 74: 2067-2081. https://doi.org/10.1007/s00445-012-0652-7

PHIVOLCS, 2018-. Volcanoes of the Philippines. https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard/volcanoes-of-the-philippines.

Eruptive History

There is data available for 0 confirmed Holocene eruptive periods.

[ 1628 ] Discredited Eruption

Slope failure of the SE flank of Iriga that was originally considered to have occurred in 1628 (more probable date) or 1641 CE produced a major debris avalanche which devastated villages at the foot of the volcano and blocked local drainages, forming Lake Buhi. Phreatic eruptions followed the avalanche and produced pyroclastic surge deposits that are mostly confined to the floor of the breached crater (Aguila et al., 1986). Although the date of the debris avalanche is not certain, the 1628 date was considered more probable than the 4 January 1641 date (Aguila et al., 1986), although this date is listed as 4 January 1642 in PHIVOLCS (2004-). The 4 January 1641 date is that of the major eruption of Parker volcano on Mindanao. Later work has shown that Jesuit priests, who would have noted such a dramatic event, were in the area in 1628 CE, so the collapse must have occurred earler during some unknown time in the Holocene (Newhall, 2008 pers. comm.).

Deformation History

There is no Deformation History data available for Iriga.

Emission History

There is no Emissions History data available for Iriga.

Photo Gallery

Mount Iriga has a horseshoe-shaped crater opening to the SE that resulted from a large flank collapse during a Holocene eruption. The hummocky terrain in the foreground encloses small ponds on the surface of the debris avalanche deposit.

Photo by Chris Newhall (U.S. Geological Survey).

Collapses at the summit or flanks of volcanoes during major volcanic landslides can create large horseshoe-shaped craters that open in the direction of the landslide, like this 2.1 x 3.5 km crater at Iriga in the Philippines. It was produced by a massive landslide during the Holocene. The resulting debris avalanche traveled more than 10 km to the SE and flowed into Lake Buhi at the upper right. This view is from the south, with the summit to the left.

Photo by Chris Newhall (U.S. Geological Survey).

This view looks W into the Iriga crater that formed at the base of the 600-m-high headwall scarp of a flank collapse during a Holocene eruption.

Photo by Chris Newhall (U.S. Geological Survey).

The entire foreground area in this view of Iriga volcano is a massive 1.5 km³ debris avalanche deposit formed by a Holocene landslide. This view from the SE shows the typical hummocky debris avalanche topography. Many of the darker areas are tree-covered hummocks; the irregular topography of the also creates many small ponds.

Photo by Chris Newhall (U.S. Geological Survey).

GVP Map Holdings

Maps are not currently available due to technical issues.

Smithsonian Sample Collections Database

There are no samples for Iriga in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

External Sites

Copernicus Browser

The Copernicus Browser replaced the Sentinel Hub Playground browser in 2023, to provide access to Earth observation archives from the Copernicus Data Space Ecosystem, the main distribution platform for data from the EU Copernicus missions.

MIROVA

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

MODVOLC Thermal Alerts

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

WOVOdat
   Single Volcano View
   Temporal Evolution of Unrest
   Side by Side Volcanoes

WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.

GVMID Data on Volcano Monitoring Infrastructure The Global Volcano Monitoring Infrastructure Database GVMID, is aimed at documenting and improving capabilities of volcano monitoring from the ground and space. GVMID should provide a snapshot and baseline view of the techniques and instrumentation that are in place at various volcanoes, which can be use by volcano observatories as reference to setup new monitoring system or improving networks at a specific volcano. These data will allow identification of what monitoring gaps exist, which can be then targeted by remote sensing infrastructure and future instrument deployments.

Volcanic Hazard Maps

The IAVCEI Commission on Volcanic Hazards and Risk has a Volcanic Hazard Maps database designed to serve as a resource for hazard mappers (or other interested parties) to explore how common issues in hazard map development have been addressed at different volcanoes, in different countries, for different hazards, and for different intended audiences. In addition to the comprehensive, searchable Volcanic Hazard Maps Database, this website contains information about diversity of volcanic hazard maps, illustrated using examples from the database. This site is for educational purposes related to volcanic hazard maps. Hazard maps found on this website should not be used for emergency purposes. For the most recent, official hazard map for a particular volcano, please seek out the proper institutional authorities on the matter.

IRIS seismic stations/networks

Incorporated Research Institutions for Seismology (IRIS) Data Services map showing the location of seismic stations from all available networks (permanent or temporary) within a radius of 0.18° (about 20 km at mid-latitudes) from the given location of Iriga. Users can customize a variety of filters and options in the left panel. Note that if there are no stations are known the map will default to show the entire world with a "No data matched request" error notice.

UNAVCO GPS/GNSS stations

Geodetic Data Services map from UNAVCO showing the location of GPS/GNSS stations from all available networks (permanent or temporary) within a radius of 20 km from the given location of Iriga. Users can customize the data search based on station or network names, location, and time window. Requires Adobe Flash Player.

DECADE Data

The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the Mapping Gas Emissions (MaGa) Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO₂ to the atmosphere, but installing CO₂ monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere.

Large Eruptions of Iriga

Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

EarthChem

EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).