Someones are nervous.
PHIVOLCS, the Philippine Institute of Volcanology and Seismology publishes a daily "Volcano Bulletin" with information about current activity of the monitored volcanoes in the Philippines.
These "Volcano Bulletins" contain a lot of interesting background information, but they are like photos. They show just one moment. Volcanism is a dynamic process. So we started 4 years ago to collect the PHIVOLCS information.
Below you find the activity curves of the 3 recently most active volcanoes, Mayon, Taal and Bulusan. More information about all volcanoes in the Philippines can be found in our "Philippines Volcanoes page".
Mayon Volcano is the Philippines' most active volcano and is considered to be the world's most perfectly formed volcano for its symmetrical cone. It is a basaltic-andesitic volcano.
The upper slopes of the volcano are steep averaging 35-40 degrees and are capped by a small summit crater. Its sides are layers of lava and other volcanic material. Mayon has had forty-seven eruptions in recorded history.
The first recorded eruption was in 1616, the last major eruption ceased on 1st October 2006, although a devastating lahar followed on 30 November 2006.
The most destructive eruption of Mayon occurred on February 1, 1814. Lava flowed but not as much compared to the 1766 eruption.
PHIVOLCS is closely monitoring Mayon Volcano and any new development will be relayed to all concerned.
Taal volcano is one of the most active volcanoes in the Philippines and has produced some of its most powerful historical eruptions. In contrast to Mayon volcano, Taal is not topographically prominent, but its prehistorical eruptions have greatly changed the topography of SW Luzon.
The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 sq km surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, and several eruptive centers lie submerged beneath the lake.
There have been 33 recorded eruptions at Taal since 1572. One of the more devastating eruptions occurred in 1911, which claimed more than a thousand lives. The deposits of that eruption consisted of a yellowish, fairly decomposed (non-juvenile) tephra with a high sulfur content.
Although the volcano has been quiet since 1977, it has shown signs of unrest since 1991, with strong seismic activity and ground fracturing events, as well as the formation of small mud pots and mud geysers on parts of the island.
Field measurements on 18 February 2016 at the eastern sector of the Main Crater Lake yielded a slight decrease in water temperature from 30.8°C to 30.6°C, a decrease in water level from 0.53 meter to 0.47 meter, and slight increase in acidity from pH 2.76 to 2.70. Ground deformation measurements through precise leveling surveys from November 3 to 16, 2015 indicated very slight deflation of the edifice compared to September-October survey. However, ground deformation from continuous GPS data as of Jan 27, 2016 indicated an inflationary trend since July 2014. Carbon dioxide (CO2) emission at the Main Crater Lake decreased to 1380 tons/day in January 2016 from 1566 tons/day in October 2015.
Luzon's southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 35,000-40,000 years ago. Bulusan lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon.
Crater No. 1, called Blackbird Lake, is 20 m in diameter and 15 m deep. The oval Crater No. 2 is 60 m by 30 m and 15 m deep. Crater No. 3 is about 90 m in diameter and 20 m deep and Crater No. 4, which is near the northeastern, rim opened during the 1981 eruption. There is also a 100-meter fissure measuring 5 to 8 m wide below Crater No. 4.. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.
Bulusan Volcano’s seismic monitoring network recorded eight (8) volcanic earthquakes during the past 24 hours. Weak emission of white steam plumes that crept downslope towards southwest was observed. Precise leveling survey results from December 2-7, 2015 indicated slight inflationary changes of the volcano’s edifice relative to September 2015, consistent with ground deformation measurements from continuous GPS data since August 2015.
Kanlaon volcano (also spelled Canlaon or Canla-on), the most active of the central Philippines, forms the highest point on the island of Negros. The massive 2435-m-high andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km to the SW from Kanlaon. The summit of Kanlaon contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions from Kanlaon, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.
The volcano has three hot springs on its slopes: Mambucal Hot Springs on the northwest, Bucalan Hot Spring, Bungol Hot Spring. Its adjacent volcanic edifices are Mt. Silay and Mt. Mandalagan, north of Kanlaon.
On August 10, 1996, Kanlaon erupted without warning. In the 8 days from 23 August to 1 September, 2009, 257 volcanic earthquakes were recorded. Usual seismic activity during quiet periods is 0 to 4 quakes in any 24 hour period. Epicenters of the recorded quakes were clustered at the north-west slope which may indicate movement of an active local fault at the slope induced by pressure beneath the volcano. Surface observations did not show any significant change in the steam emission from the crater." A 4 kilometre Permanent Danger Zone (PDZ) is maintained around the volcano, because sudden explosions may occur without warning. Phivolcs continuously monitors volcanic activity at Kanlaon.
Please click on above thumbnails to open large maps.
Alert Level 1 status remains in effect over Kanlaon Volcano, which means that it is currently in a state of unrest driven by hydrothermal processes that could generate more minor eruptions. The local government units and the public are reminded that entry into the 4-kilometer radius Permanent Danger Zone (PDZ) is strictly prohibited due to the further possibilities of sudden and hazardous steam-driven or minor ash eruptions. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as airborne ash from a sudden eruption can be hazardous to aircraft. DOST-PHIVOLCS is closely monitoring Kanlaon Volcano’s activity and any new development will be relayed to all concerned.
Active and potentially active volcanoes in the Philippines are monitored by PHIVOLCS.
On many islands PHIVOLCS maintains local observatories with trained staff and resident volcanologists and geologists.
The most important instruments are the 3 dimensional seismometers. These instruments measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources.
With 3 of these instruments, the origin of the motion can be determined with good precision.
Geodetic ground deformation survey (precise leveling) is regularly done on all volcanoes. Active and potentially active volcanoes are measured more frequently.
A volcano usually gets inflated by rising magma. This inflation can be detected by precise leveling.
The third monitored parameter is the quantity and the composition of the gas blown out by the volcano. Carbon dioxide is measured on Taal volcano, Sulfur dioxide emission is measured on Mayon volcano.
On Taal volcano the acidity (pH) of the waters in the crater lake is also analyzed.