‘Bulusan’s activity fluctuating’

LEGAZPI CITY, Philippines — The abnormal activity of Mt. Bulusan in Sorsogon has been fluctuating as state seismologists recorded only about 190 volcanic earthquakes in the past five days, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).

Data from the Bulusan Volcano Network showed 48 volcanic quakes recorded on Wednesday and 65 on Thursday.

From 65, the number of quakes dropped to 22 on Friday, surged to 47 on Saturday and decreased to 20 in the past 24 hours.

Bulusan maintained high levels of sulfur dioxide and plume emissions, with an accumulated volume of 2,920 tons and 1,250 meters high, respectively, in five succeeding days, Phivolcs said.

State seismologists said this sustained abnormal behavior of the volcano could lead to sudden and hazardous phreatic eruptions any time.

The increased number of volcanic quakes and plume emissions means degassing and hydrothermal activities are ongoing inside the volcano.

Bulusan’s surface remains inflated, Phivolcs said.

As long as sulfur dioxide emissions were not yet “very high,” no magma would ascend to the surface, Phivolcs officer-in-charge Renato Solidum said.

“We are closely watching the sulfur dioxide emissions to determine whether magma is already ascending to the surface. So far, we don’t see that indication yet,” Solidum told The STAR over the weekend.

He said seismologists are closely analyzing the types of earthquakes detected around the volcano.

Temblors detected in the lower and upper elevations of Bulusan indicated a magmatic ascent to the surface, Solidum said.

“These tremors must be detected in all monitoring instruments installed at the lower and upper elevations to determine active movement inside. We don’t see yet these activities,” Solidum added.

He warned that eruptions are possible any time due to the high numbers of Bulusan’s abnormal parameters.

“Its volcanic earthquakes as well as sulfur dioxide and plume emissions are considered high and can trigger phreatic eruptions. That’s why we emphasize in our advisories for people not to enter the four-kilometer-radius permanent danger zone as well as the two-kilometer extended danger zone,” he said.