emirates7 - Bulusan Volcano in Sorsogon has exhibited increased activity, with the Philippine Institute of Volcanology and Seismology (Phivolcs) reporting 69 volcanic earthquakes and 42 volcanic tremors within a 24-hour span.

In its released Saturday, Phivolcs said the recorded tremors ranged from one to 16 minutes in duration.

Unlike tectonic earthquakes, which are caused by movements along faults, volcanic earthquakes originate from within volcanoes and are typically associated with the movement of magma, Phivolcs explained.

Volcanic tremors, on the other hand, are continuous low-frequency seismic vibrations that can be linked to magma flow, minor eruptions, or other low-frequency quakes.

The volcano showed signs of unrest on April 28, when it ejected a column of ash reaching up to 4.5 kilometers (2.8 miles) into the atmosphere. In response, authorities elevated the alert level for Mount Bulusan from 0 to 1 on the five-tier scale, indicating low-level volcanic activity and the possibility of phreatic, or steam-driven, eruptions. Residents were also advised to avoid the 4-kilometer danger zone around the volcano.

Before the ash explosion between 4:36 a.m. and 5:00 a.m. on April 28, Phivolcs had already detected 53 volcanic earthquakes over a 24-hour period, and local residents reported hearing rumbling sounds.