Volcanic Advisory

This serves as a notice for the lowering of Taal Volcano’s status from Alert Level 3 (decreased tendency towards hazardous eruption) to Alert Level 2 (decreased unrest).

After step-down to Alert Level 3 last 26 January 2020, Taal Volcano’s condition in the succeeding three weeks has been characterized by less frequent volcanic earthquake activity, stabilizing ground deformation of the Taal Caldera and Taal Volcano Island (TVI) edifices and weak steam/gas emissions at the Main Crater. These observations are supported by the following monitoring parameters:

1. Since 26 January, volcanic earthquakes recorded by the Taal Volcano Network (TVN) averaged 141 events/day while the number of significant events recorded by the Philippine Seismic Network across the Taal region declined to 127 events of magnitudes M1.4 to M4.3. The number and energy of tremor and low-frequency events associated with activity in the shallow magma and hydrothermal region beneath the TVI edifice have also diminished. These parameters are consistent with degassing ponded magma rather than active magma transport to and from the shallow magma reservoir beneath TVI.

2. Continuous Global Positioning System (GPS) data from 13 January to 11 February recorded a net subsidence of the Taal Caldera and TVI, following uplift on the northwestern caldera and subsidence of TVI on 12-13 January. Subsidence along thePansipit River Valley, where extensive fissuring occurred, was also recorded by campaign GPS monitoring between 24 and 27 January. The overall ground deformation behavior of Taal Volcano for the above periods indicates post-eruptive subsidence and relaxation of the edifice after the cessation of magma transport, signaled by hybrid earthquake activity, on 18 January.

3. Sulfur dioxide or SO2 flux based on campaign Flyspec data averaged 62 tonnes/day since 26 January, consistent with a weakly degassing shallow magma source, diminished plume activity or absorption of volcanic gas by a recovering lake at the Main Crater and by TVI’s recovering hydrothermal system.

4. Activity in the Main Crater has been characterized by the generation of weak steam-laden plumes, consistent with decreased magmatic unrest. In view of the above observations, DOST-PHIVOLCS is lowering the alert status of TaalVolcano from Alert Level 3 to Alert Level 2 to reflect the overall decreasing trend in the level of monitoring parameters. Alert Level 2 means that there is decreased unrest but should not be interpreted that unrest has ceased or that the threat of an eruption has disappeared. Should an uptrend or pronounced change in monitored parameters forewarn a potential eruption, the Alert Level may be raised back to Alert Level 3. At such time, people potential eruption, the Alert Level may be raised back to Alert Level 3. At such time, people residing within areas at high risk to base surges who have returned after the step-down to Alert Level 2 must therefore be prepared for a quick and organized evacuation. Conversely, should there be a persistent downtrend in monitored parameters after a sufficient observation period, the Alert Level will be further lowered to Alert Level 1.