Kanlaon Volcano on Monday recorded 21 volcanic earthquakes in the past 24 hours as Phivolcs observes increased activity in the area.
The volcano, located in the Negros provinces southeast of Bacolod City, also has a slight inflation or swelling due to the increased activities, which includes at least seven "very shallow tornillo signals" or low frequency seismic activities that could be associated with volcanic gas movement, Phivolcs said in a Sunday advisory.
It has also tallied 41 volcanic earthquakes since 5 a.m. of June 30, Phivolcs said.
State volcanologists said this could be due to the hydrothermal activities beneath the volcano, which could trigger steam-driven eruptions.
The volcano remains under Alert Level 1 or low-level unrest, according to Phivolcs. It warned against the entry into the four-kilometer radius permanent danger zone and flying aircrafts close to the volcano.