I. SITUATION OVERVIEW
Bulusan Volcano (12=B046.2'N, 124=B003'E) seismic netwo rk recorded sixteen (16) volcanic earthquakes during the past 24 hours. Two of these events, which occurred at 9:12 AM and 10:27 AM, 21 February 2011, were recorded as explosion type earthquakes. The first explosion was accompanied by rumbling sound which was heard up to ten (10) kilometres away in the town of Juban, Sorsogon. The explosion produced a greyish ash column that rose to a height of about three (3) kilometres above the summit before drifting to the southwest. Field investigation confirmed the presence of ash deposit in the town of Irosin (up to 5mm) and Bulan (up to 3mm) in Sorsogon. Traces of ash deposits were also reported in the municipalities of Juban and Magallanes, Sorsogon and in Masbate City, Masbate.
Alert Level 1 remains hoisted over Bulusan Volcano which means that the source of activity is hydrothermal and shallow
- The public is strongly advised not to enter inside the 4-kilometer radius Permanent Danger Zone (PDZ) as it may be affected by sudden steam and ash explosions.
- People residing near valleys and river/streams are also strongly advised to be vigilant against sediment-laden stream flows in the event of heavy and prolonged rainfall.
- Due to the prevailing wind direction, residents located in the northwest and southwest sectors of the volcano are advised to take precautions against ashfalls.
- Civil aviation authorities must advise pilots to avoid flying close to the volcano's summit as ejected ash and volcanic fragments from sudden explosions may pose hazards to aircrafts.