PHIVOLCS reported ongoing unrest at Taal during 13-21 May. Daily upwelling of gases and hot fluids in the lake generated steam-and-gas plumes that rose as high as 2.4 km above the crater rim and drifted WNW. Sulfur dioxide emissions increased to 5,094 tonnes per day (t/d) on 13 May. A phreatic event began at 1345 on 15 May, lasted about five minutes, and produced a steam plume that rose 500 m above Main Crater rim and drifted W and NW. On 16 May a series of short phreatic events were visible in webcam images and detected by the seismic network during 0854-0857, 1107-1110, 1348-1350, 1737-1738, and a fifth that ended at 2303. The events produced steam plumes that rose 50-300 m and drifted WNW. Sulfur dioxide emissions decreased to 3,823 t/d on 20 May. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ) and to take extra precautions around Main Crater, when boating on Taal Lake, and along the Daang Kastila fissure.

Geological Summary. Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)