In a 2 June advisory PHIVOLCS reported continuing low-level unrest at Taal. Starting at 0635 on 2 June relatively weak but continuous volcanic tremor located at shallow depths along the Daang Kastila fissure was recorded by all 15 seismic stations of the Taal Volcano Network. At the same time webcams recorded upwelling in Main Crater Lake on Taal Volcano Island (TVI) and more intense thermal anomalies in the N portion of the lake. Pronounced inflation in the SW part of Taal Volcano Island was detected towards the end of May, following a longer phase of deflation in that same sector. Sulfur dioxide gas emissions had slightly increased during the previous two weeks, averaging 5,360 tonnes per day during 22 May-1 June, higher than the 3,000 tonnes per day average recorded during 1 April-21 May. Emissions averaged 5,831 tonnes per day on 1 June. PHIVOLCS stated that a new phase of magma degassing at depth was likely driving the increased shallow hydrothermal activity.

At 2230 on 3 June visible upwelling of volcanic fluids in the lake produced voluminous steam-rich plumes that rose 3 km above TVI. Significant vog was detected in the caldera and reported by residents in the municipalities of Balete (E of Taal Lake), and Laurel and Agoncillo (both W of Taal Lake), Batangas. Upwelling of how fluids in the lake continued during 4-7 June and steam-rich plumes rose as high as 3 km above the lake and drifted NE and NNE. Sulfur dioxide gas emissions averaged 9,391 tonnes per day on 5 June and 7,680 tonnes per day on 6 June; significant vog persisted over the Taal region. 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)