PHIVOLCS reported increases in both sulfur dioxide emissions at Taal and activity in Main Crater Lake. Sulfur dioxide emissions averaged 1,289 tonnes per day from May to mid-June, and increased to an average of 4,952 tonnes per day during 15 July-3 August. Sulfur dioxide emissions further increased to 12,125 and 17,141 tonnes per day on 3 and 7 August, respectively, prompting PHIVOLCS to issue advisories. Vog was present over the W part of Taal Caldera during 2-3 August; dense vog in Laurel and Banyaga (Agoncillo, Batangas Province) also damaged vegetation. A sulfur odor was reported by residents of Tagaytay City and Bugaan East. Upwelling gasses and hot fluids in the lake, and voluminous steam-rich plumes rising as high as 2.8 km above the lake, were visible during 1-9 August. Recent low-frequency seismic events and tremor were characterized as above background. 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).

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)