Isarog
Mt. Isarog is a stratovolcano located in the province of Camarines Sur, rising to a peak elevation of 1,972 meters above sea level. It is part of the Bicol Volcanic Arc which includes other prominent volcanoes such as Mayon and Iriga. With a basal width of 30.97 kilometers and a volume of 174 cubic kilometers, it encompasses 6 municipalities and one city – Goa, Tigaon, Ocampo, Pili, Naga City, Tinambac, and Calabanga.
The volcano is primarily composed of andesitic and dacitic lava flows, pyroclastic deposits, and volcanic breccias, indicating an explosive eruptive history. It is classified by PHIVOLCS as active, with the last recorded eruptive activity estimated to have occurred around 3500 BCE (approximately 5,500 years ago). It has a breached edifice facing east along a narrow valley drained by the Rangas River. Currently, Mt. Isarog vent displays gas seepages, warm springs, and steaming vents.
Mt. Isarog is home to the Mount Isarog National Park (MINP), covering about 100 square kilometers, and is globally recognized as a Key Biodiversity Area (KBA) due to its rich and diverse flora and fauna. Its montane forests host a wide array of endemic species, such as the Isarog shrew-rat (Rhynchomys isarogensis) and various orchids and mosses found only in this region. Its unique climate gradient from lowland rainforest to mossy forests at higher altitudes supports high levels of biodiversity, making it a prime area for ecological and conservation studies.
Historically, Mt. Isarog played an important role during the World War II. It served as a strategic stronghold for Filipino guerrilla fighters, who used its caves and dense forests to evade Japanese forces. The Guerrilla Caves near Barangay Panicuason, Naga City remain a historical site to this day.
Numerous literary pieces, including folklore, contain accounts of the cultural significance and relevance of Mt. Isarog. The name Isarog as a mountain has eight etymological explanations, according to the Camarinense elders – these accounts of the natives were classified as literary myths. The “Legend of Mt. Isarog” tells the love story of Isaray and Dimaarog, where the combination of their names eventually became the name of their son Isarog. Another tale, Isog (Courage), was narrated by an Agta descendant who said that the Isarog name refers to the sense of boldness of native inhabitants. At least 44 Camarinense literary pieces were identified to contain the different stories about Mt. Isarog, which are either related to faith or cultural history.
Other Names: –
Latitude and Longitude: 13.65691 123.38103
Region: Region 5
Tectonic Setting: Subduction zone (Philippine Trench)
Volcanic Arc/Belt: Bicol Volcanic Arc Complex
Volcanic Region/Field: Bicol Volcanic Region
Volcano Type: Stratovolcano
Last Known Eruption: 3500 BCE ± 125 years
Morphometry Type: Breached edifice
Highest Peak (masl): 1972
Coordinates of Highest Peak: 13.65937 123.37279
Prominence (m): –
Basal Area (km2): 753.4
Basal Width (km): 30.97
Volume (km3): 174
How to cite this page:
UPRI (2025). Isarog: Volcanoes of the Philippines (NOAH Open File Reports). Distributed by the University of the Philippines Resilience Institute, compiled by Alexis Bryan G. Rivera. ISSN 2362 7409.
References:
Aurelio, Mario & Peña, Rolando. (2010). Geology of the Philippines, 2nd Edition (2010)
Fontijn, K., & Newhall, C. G. (2012). Reconnaissance geology of Isarog volcano (Luzon, Philippines): Evidence for Holocene explosive eruptions and a major edifice collapse. Journal of Volcanology and Geothermal Research, 250, 100–105. https://doi.org/10.1016/j.jvolgeores.2012.11.003
Global Volcanism Program (2025). Isarog (273042) in [Database] Volcanoes of the World (v. 5.2.7; 21 Feb 2025). Distributed by Smithsonian Institution, compiled by Venzke, E. https://volcano.si.edu/volcano.cfm?vn=273042
Gratela-Caballero, M. (2023). Mt. Isarog Literature: A Showcase of Camarinense Cultural Diversity. Advances in Literary Study, 11, 328-349. doi: 10.4236/als.2023.113023
Key Biodiversity Areas Partnership (2025). Key Biodiversity Areas factsheet: Mount Isarog National Park. Extracted from the World Database of Key Biodiversity Areas. Developed by the Key Biodiversity Areas Partnership: BirdLife International, IUCN, American Bird Conservancy, Amphibian Survival Alliance, Conservation International, Critical Ecosystem Partnership Fund, Global Environment Facility, Re:wild, NatureServe, Rainforest Trust, Royal Society for the Protection of Birds, World Wildlife Fund and Wildlife Conservation Society. Downloaded from https://keybiodiversityareas.org/ on Apr 15, 2025.
Mines and Geosciences Bureau (2010). Geology of the Philippines, 2nd edition. Mines and Geosciences Bureau, Department of Environment and Natural Resources.
Paguican, E. M. (2012, July 9). The structure, morphology, and surface texture of debris avalanche deposits: field and remote sensing mapping and analogue modelling. https://theses.hal.science/tel-00794267
National Mapping and Resource Information Authority. (2024). 1:50,000 Scale Mount Isarog Map. https://namria.gov.ph/downloads/topomap50/3660-IMountIsarog.jpg
Paguican, E. M., Grosse, P., Fabbro, G. N., & Kervyn, M. (2021). Morphometric classification and spatial distribution of Philippine volcanoes. Journal of Volcanology and Geothermal Research, 418, 107251. https://doi.org/10.1016/j.jvolgeores.2021.107251
PHIVOLCS. 2023. Lava flow hazard map of Isarog Volcano. https://gisweb.phivolcs.dost.gov.ph/gisweb/storage/hazard-maps/region-ii-(cagayan-valley)/batanes/provincial/volcano/lava-flow/lav_2023_020900000_01.png
/batanes/provincial/volcano/lava-flow/lav_2023_020900000_01.png){kind=link}
PHIVOLCS. 2023. Pyroclastic density current and lahar hazard map of Isarog Volcano. https://gisweb.phivolcs.dost.gov.ph/gisweb/storage/hazard-maps/region-ii-(cagayan-valley)/batanes/provincial/volcano/lahar/lhr_2023_020900000_01.png
/batanes/provincial/volcano/lahar/lhr_2023_020900000_01.png){kind=link}
PHIVOLCS-LAVA Eruption History. https://wovodat.phivolcs.dost.gov.ph/volcano/erupt-history
PHIVOLCS. 2023. Lahar hazard map of Isarog Volcano. https://gisweb.phivolcs.dost.gov.ph/gisweb/storage/hazard-maps/region-ii-(cagayan-valley)/batanes/provincial/volcano/lava-flow/lav_2023_020900000_01.png
Siebert, L., Simkin, T., & Kimberly, P. (2010). Volcanoes of the world. Smithsonian Institution ; Berkeley.
Smithsonian Institute. (2013). Global Volcanism Program | Jolo. Smithsonian Institution | Global Volcanism Program. https://volcano.si.edu/volcano.cfm?vn=270010