Manila, May 12 -- The Philippine Institute of Volcanology and Seismology (Phivolcs) reported an increase in Kanlaon Volcano's seismic activity on Monday.

Seventy-two volcanic earthquakes were recorded from 12 a.m. to 12 p.m. Their magnitudes ranged from 0.3 to 3.1, and were 0 to 8 kilometers deep beneath the northern and northwestern flanks of the volcanic edifice.

Phivolcs said 135 volcanic earthquakes were recorded since 12 a.m. of May 11, and these included relatively strong volcano-tectonic (VT) earthquakes.

VTs are generated by rock fracturing processes and the increase in VT activity strongly indicates progressive rock fracturing beneath the volcano as rising magma or magmatic gas drives a path towards the surface.

Meanwhile, su...