11/07/2022
TAAL VOLCANO BULLETIN
11 July 2022
8:00 AM
This serves as a notice for the lowering of Taal Volcano’s status from Alert Level 2 (Decreased Unrest) to Alert Level 1 (Low-Level Unrest).
Taal Volcano’s condition in the past two months has been characterized by baseline volcanic earthquake activity, stabilizing ground deformation of the Taal Caldera and Taal Volcano Island (TVI) edifices and weak degassing and surface activity at the Main Crater. These observations are supported by the following monitoring parameters:
1. Volcanic Earthquakes: The Taal Volcano Network (TVN) recorded a decline in the daily average of volcanic earthquakes from seven (7) events/day between 1 January and 31 May 2022 to zero (0) events/day since 13 June 2022. The sustained seismic quiescence for the past month indicates that degassing and rock-fracturing processes related to magmatic activity beneath TVI have abated, and that the possibilities of magma intrusion into the Main Crater have significantly decreased.
2. Ground Deformation: Continuous Global Positioning System (GPS) monitoring from November 2021 to April 2022 and Interferometric Synthetic Aperture Radar (InSAR) monitoring from January 2021 to June 2022 using ESA Sentinel-1 data recorded short- to medium-term deflation of Taal, with TVI deflation rates particularly declining (or slowing down), and slight uplift of western Taal Caldera. Such motions have been consistent with the overall ground deformation behavior of Taal Volcano since January 2020 and broadly with post-eruptive deflation of the Taal edifice.
3. Volcanic Gas Emission: Sulfur dioxide or SO2 flux based on campaign Flyspec data averaged 1,214 tonnes/day between May and July 2022, with the latest emission rates falling to 237 tonnes/day. Such low concentrations are consistent with weakened degassing from magma beneath TVI and volcanic gas being efficiently absorbed by the Main Crater Lake and by Taal’s recovered hydrothermal system.
4. Main Crater Observations: Surface activity has declined to weak emission of 300- to 2,400-meter tall steam-rich plumes from fumaroles or active gas vents on the Main Crater. The last significant activities from the Main Crater were phreatomagmatic bursts on 2 and 10 February and 26 March 2022 that respectively spewed 300- and 3,000-meter tall steam-rich plumes. Since then, background hydrothermal activity in the Main Crater Lake has been quietly transpiring.
In view of the above, DOST-PHIVOLCS is lowering the alert status of Taal Volcano from Alert Level 2 to Alert Level 1 to reflect the overall decrease in the level of monitoring parameters. Alert Level 1 means that the volcano is still in abnormal condition and 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 of renewed unrest, the Alert Level may be raised back to Alert Level 2. Residents of areas at high risk to base surges who have returned after the step-down to Alert Level 2 on 23 July 2021 must therefore remain vigilant and always prepared for a quick and organized evacuation. Conversely, should there be a return of monitoring parameters to baseline levels after a sufficient observation period, the Alert Level will be further lowered to Alert Level 0.
DOST-PHIVOLCS reminds the public that at Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within TVI. DOST-PHIVOLCS strongly recommends that entry into TVI, Taal’s Permanent Danger Zone or PDZ, especially the vicinities of the Main Crater and the Daang Kastila fissure, must remain strictly prohibited. Local government units are advised to continuously assess previously evacuated barangays around Taal Lake for damages and road accessibilities and to strengthen preparedness, contingency and communication measures in case of renewed unrest. People are also advised to observe precautions due to ground displacement across fissures, possible ashfall and minor earthquakes. Civil aviation authorities must advise pilots to avoid flying close to the volcano as airborne ash and ballistic fragments from sudden explosions and wind-remobilized ash may pose hazards to aircrafts.
DOST-PHIVOLCS is closely monitoring Taal Volcano’s activity and any new significant development will be immediately communicated to all stakeholders.
Source: DOST-PHIVOLCS
https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard/volcano-bulletin2/taal-volcano/15224-taal-volcano-bulletin-11a-july-2022-8-00-am
