Mount Isarog

Isarog is an active stratovolcano located in the province of Camarines Sur, Philippines, on the island of Luzon. The mountain has active fumaroles and hot springs. It has an elevation of above mean sea level.

The broad isthmus between Lagonoy Gulf and San Miguel Bay is occupied by the isolated Isarog volcano.

The volcano has a 2,500 m (8202 ft) crater that is breached to the east along a narrow valley drained by the Rangas River. A major debris avalanche deposit extends northwest to the coast and into San Miguel Bay.

The peak of the mountain marks the point where the borders of six municipalities and one city meet (listed in clockwise direction, starting north): Goa, Tigaon, Ocampo, Pili, Naga City, Tinambac and Calabanga.

Isarog Volcano was where local troops of the Philippine Army and Constabulary units and Bicolano guerrillas hid during the Japanese Occupation. In the 1970s, with the leadership of Romulo Jallores and his brother, they established the New People's Army in the Bicol region at the foot of this mountain.

Geology

Isarog Volcano is interpreted to have formed during the Pleistocene, as indicated by K-Ar dating of lava samples from the edifice, which yielded an age of 0.16 ± 0.12 Ma. The magmatic composition of Isarog Volcano is primarily andesitic, with minor dacitic components.

Eruptive history

Block-and-ash flows originating from lava dome collapses have occurred during the Holocene, one of which has a calibrated radiocarbon date of about 3,500 BCE. In 2020, a group of geologists from Partido State University discovered that Isarog also erupted around 4,300 years ago after a charcoal overlain by thick block-and-ash flow deposits was found. The charcoal was sent to the United States for radiocarbon dating. This new information about the eruptive history of Isarog was presented at the 2020 Virtual GeoCon, a convention of geologists organized by th
Geological Society of the Philippines
Currently, Isarog vent displays gas seepages, warm springs, and steaming vents.

Reports of Unusual Activity

On November 8, 1915, frequent earthquakes were felt on and around Isarog volcano, with some occasional noises. Landslides occurred on the slopes of Isarog volcano. The seismic swarm repeated itself 2 or 3 times at long intervals until January 10, 1916. The volcano was thickly wooded, even inside of the crater, and nobody observed any fumaroles.

History

Indigenous history

Isarog Volcano has been the ancestral territory of the indigenous Isarog Agta people for thousands of years prior to the arrival of the Spanish. They were among the first inhabitants in the entire Philippines and are of Negrito origin. They are a group of Aeta people with a distinct language and heritage unique from others.

Legal history

It was made a public land through the ''Proclamation No. 157'' on March 28, 2015. Towns around it is classified as timberland forest with an area of .

On August 17, 1935, General Frank Murphy established the ''Mt. Isarog Forest Reserve'' which reduced the size of the area to 10,112. But it was revoked by President Manuel L. Quezon when he signed ''Proclamation No. 293'' titled "Establishment of Mt. Isarog as a National Park."

The ''Earth Summit'' of 1992 prompted the creation of the National Integrated Protected Area Programme. A five-year (1995-2001) intervention plan was enacted. On June 20, 2002, by virtue of ''Proclamation No. 214'' signed by President Gloria Macapagal-Arroyo, Mt. Isarog became a protected area under the natural park.

Ethnic groups

Isarog Agta Tribe

The Isarog Agta people live within the circumference of Isarog Volcano, though only 5 of them still know their indigenous language. They are one of the original Negrito settlers in the entire Philippines. They belong to the Aeta people classification, but have distinct language and belief systems unique to their own culture and heritage.

In 2010, UNESCO released its 3rd world volume of Endangered Languages in the World, where 3 critically endangered languages were in the Philippines. One of these languages in the ''Isarog Agta'' language which has an estimated speaker of 5 people in the year 2000. The language was classified as ''Critically Endangered'', meaning the youngest speakers are grandparents and older, and they speak the language partially and infrequently and hardly pass the language to their children and grandchildren anymore. If the remaining 150 people do not pass their native language to the next generation of Isarog Agta people, their indigenous language will be extinct within a period of 1 to 2 decades.

Biodiversity

Mt. Isarog has a rich diversity. It displays four major types of natural habitat or vegetation: from the warm grassland and lowland forest to the wet and cool climate of montane forest.

The lowland forest is noted for its tall canopy. The uppermost layer towers between 30 and 40 meters and sometimes even reach 60 meters. Many of these trees belong to the dipterocarp family. The second canopy layer (between 23 and 30 meters) has the sustain bamboos (Bambusa), arborescent palms (Calamus), climbing bamboo (Schizostacyum), climbing pandans (Freycinetia) and vascular epiphytes such as orchids and ferns.

The grassland (''parang'') is dominated by cogon (''Imperata cylindrica'') and ''talahib'' ('' Saccharum ovatum'') grasses. The topography and soil condition of the area limits the growth of trees, giving rise to the grassland.

The montane forest has two-oken because layered canopy trees ranging from 12 to 25 meters with noticeable canopy gaps due to the absence of large trees.

The mossy forest has a canopy with a small height of 2 to 6 meters only. The canopy is broken because of the high winds and steep terrain. It is inhabited by bamboo, pandan, orchids, ferns, pitcher plants and other epiphytes. Trees at this level are covered with moss.

Endemic

Isarog Shrew rat (''Rhynchomys isarogensis'') was first discovered in 1988 in Isarog Volcano. Although it has no direct economic value, its presence in Isarog Volcano is a barometer of wealth and management of its natural resources. It is now listed as endangered in the Red Data Book of the International Union for Conservation of Nature.

Isarog Volcano is included as a protected area, home to endemic rodents ('' Archboldomys luzonensis'', '' Chrotomys gonzalesi'' and '' Rhynchomys isarogensis''), other endemic mammals, and 15 bird species endemic to Luzon.

Isarog Cloud Frog was first described by scientists in 1997. In total, scientists have identified one and possibly three new frog species, 8 species of snakes, and 19 species of lizards.

Isarog Volcano also has the rare Mount Isarog Forest Skink ('' Sphenomorphus knollmanae'') that is endemic.

Gallery

View of Mt. Isarog from Naga Airport.jpg, From Pili, Camarines Sur
File:A view of Mt. Isarog 03.JPG, From San Jose, Camarines Sur
Mt Isarog viewed from Naga City.jpg, From Naga, Camarines Sur
Mountain view 4.jpg, From Ocampo, Camarines Sur

See also

* List of volcanoes in the Philippines
**List of active volcanoes in the Philippines
** List of potentially active volcanoes in the Philippines
**List of inactive volcanoes in the Philippines
* List of protected areas of the Philippines
** List of natural parks of the Philippines
* Philippine Institute of Volcanology and Seismology
* Pacific ring of fire

References

External links

*

Phivolcs' Mount Isarog page

"Mount Isarog, Philippines" on Peakbagger

{{DEFAULTSORT:Isarog, Mount
Mountains of the Philippines
Volcanoes of Luzon
Stratovolcanoes of the Philippines
Mount Isarog
Potentially active volcanoes of the Philippines
Landforms of Camarines Sur
Holocene stratovolcanoes