Bulusan Update (May 17, 2011): Earthquakes increase and evacuation centers established

After last week’s steam-driven phreatic explosions, it might have been expected that Bulusan would go back to being quiet – that has been the pattern for over 8 months since the volcano began showing signs of renewed activity. However, it seems that the volcano might have other ideas as the seismicity under Bulusan increased dramatically in the past 24 hours, with PHIVOLCS registering 144 earthquakes, all of which suggest magma rising under the volcano. Yet, even with these earthquakes, PHIVOLCS says “a magmatic explosion is not expected to occur” but more phreatic explosions are possible. PHIVOLCS is also warning that towns to the west of Bulusan, along with any aircraft flying on that side of the volcano, are likely to see the most ash if more explosions occur. People living near the volcano were also warned to be watchful for potential lahars generated if there is significant rainfall. Even with all this activity, PHIVOLCS is keeping Bulusan at Alert Status 1.

In preparation for any new eruptive activity at Bulusan (and also at Mayon, which has seen a slight increase in seismicity as well), the Philippine government has established 39 evacuation centers near each volcano do deal with any refugees. No evacuations have been called in either case, but preparations are clearly being made.

Top left: An undated image of Bulusan with a prominent steam plume on the volcano.