PHIVOLCS reported ongoing unrest at Taal during 13-18 September. Daily emissions of gas-and-steam rose from Main Crater Lake generally as high as 2.4 km, were sometimes voluminous, and drifted ENE, ESE, SW, and NW. Upwelling gasses and fluids in the lake were visible during daily observations. During 14-18 September there were 2-4 daily volcanic earthquakes recorded by the seismic network, including 1-3 daily periods of tremor each lasting 1-2 minutes long. Sulfur dioxide emissions averaged 3,264 tonnes per day on 15 September and coupled with taller steam-and-gas plumes that rose as high as 3 km, caused vog over Taal Lake beginning at around 1000. PHIVOLCS noted that vog had been affecting the Taal region since the first week of September. 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)