MANILA, Philippines — A volcanic tremor at Taal Volcano persisted for 10 hours and 30 minutes from Saturday, October 12, to Sunday, October 13, according to Phivolcs.
While Taal Volcano did not erupt on Saturday as per today’s advisory, it experienced tremors that lasted nearly half a day. The volcano remains at Alert Level 1 or a low-level unrest.
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This phenomenon was not observed in the past week as volcanic tremors and earthquakes only lasted a few minutes.
What is a volcanic tremor? According to Phivolcs, a volcanic tremor “is a continuous seismic signal with regular or irregular sine wave appearance and low frequencies.”
In simpler terms, a tremor is a small, shaking movement of the ground. It is similar to an earthquake, but a tremor is more sustained than an earthquake that occurs in sharp bursts of energy from the earth’s crust.
A tremor is caused by the movement of magma and gas pressure beneath the volcano, while an earthquake occurs due to movement in tectonic plates. This may also indicate the possibility of an eruption.
The US Geological Survey said that tremors can last anywhere from a few minutes to hours or several days during ongoing eruptions.
Sulfur dioxide flux. As of Saturday, October 12, Phivolcs recorded a sulfur dioxide emission rate of 1,256 tons per day, with a plume reaching 900 meters and drifting southwest.
The state seismology bureau downgraded the classification to "moderate emissions.”
This rate is lower than the previous measurement of 2,256 tonnes per day recorded on October 9, which was classified as “voluminous.”
Eruptions. Since September 22, Taal Volcano has experienced over 40 phreatic and phreatomagmatic eruptions.
However, the past week has seen a decrease in eruption frequency compared to an October 6 advisory, which stated that the volcano recorded six phreatic eruptions and one phreatomagmatic eruption.
Nearly every day since last week, at least one eruption event has occurred.
The two most recent advisories reported a total of two phreatic eruptions: the October 11 advisory noted an eruption lasting six minutes, while the Saturday advisory recorded a two-minute eruption.
The state seismology bureau issues daily advisories on volcanic activity covering the past 24 hours, from 12 a.m. of one day to 12 a.m. of the next day.