PHIVOLCS lowers Taal alert level due to low-level volcanic quake activity, weak emissions

(Eagle News)–The Philippine Institute of Volcanology and Seismology has lowered the alert level on Taal after it noted low-level volcanic earthquake activity and weak emissions of steam-laden plumes, among others.

In an advisory, PHIVOLCS said from alert level 2 or decreased unrest, Taal’s alert level was now number 1 or abnormal.

According to PHIVOLCS, Taal’s condition in the succeeding four weeks after a step-down to Alert Level 2 on February 14  has been characterized by “stabilizing  ground deformation of the Taal Caldera and Taal Volcano Island (TVI) edifices and weak surface activity at the main crater and the Daang Kastila fissure.”

PHIVOLCS said these observations are supported by the decline in the daily average of volcanic earthquakes from 141 events per day between  January 26 and February 14 to 31 events per day between  February 14 and today.

The majority of these earthquakes, PHIVOLCS said, were “associated with rock-fracturing processes” and only six   low frequency events associated with magmatic or hydrothermal activity were detected until March 6.

The continuous Global Positioning System (GPS) monitoring from  February 14 to March 16 also recorded “very slow and slight uplift of the northern sector of Taal Caldera but continuing subsidence of the southern sector of the caldera and southern TVI,” which “are broadly consistent with post-eruptive relaxation of the Taal edifice.”

Sulfur dioxide also averaged 56 tons per day between February 14 and 17  before falling below detection limits in the succeeding days.

Surface activity has also “abated to weak emission of 50-100-meter tall steam-laden plumes..”

“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,” PHIVOLCS, however, said.

It said residents must still, however, remain vigilant and always prepared for a quick and organized evacuation.