SORSOGON CITY, Philippines – Disaster officials in Sorsogon City and Bicol region are watching Mount Bulusan closely after two small eruptions in one week.
Bulusan is notorious for sudden eruptions that defy instruments of prediction. How do disaster officials manage the unpredictable?
Pia Ranada reports:
Four years since its last major eruption, Bulusan Volcano is rumbling again.
Two steam-driven explosions have occurred in a span of a week.
Disaster officials in nearby Sorsogon City are on volcano watch.
Alert Level 1 has been raised, prompting evacuations of residents within the 4-kilometer Permanent Danger Zone.
Bulusan could be gearing up for a big one, says Phivolcs.
LOUIE VELASCO, SCIENCE RESEARCH ANALYST, PHIVOLCS-SORSOGON: For the past few years, nangyayari talaga siya sa Bulusan. Medyo maliliit na ash explosion, phreatic eruption. At susundan yan ng mas malaki. May posibilidad yan. kasi for the past years, in 2011, nangyayari po yan.
(For the past few years, that's what's been happening in Bulusan. Small ash explosions, phreatic eruptions followed by a big eruption. That's possible because for the past years, in 2011, that happened)
But Bulusan is a tricky volcano to predict because it's most common type of eruption, the phreatic eruption, is unpredictable.
Phreatic eruptions spew steam, ash and rock fragments.
RENATO SOLIDUM JR, DIRECTOR, PHIVOLCS: At alert level 0, steam driven explosions can happen. One cannot really predict those because those events are superficial. It's at the surface and you would not be able to detect those if ever there are signs. Typically there are not. And the lead time if ever for those signs would be very short.
But how to manage the unpredictable?
That's where Permanent Danger Zones or PDZs come in.
Communities inside PDZs are the first to be evacuated when Alert Level 1 is raised.
As the alert level increases, communities even outside the PDZ are evacuated.
The distance of PDZs differ for every active volcano.
These danger zones are delineated by markers.
Unfortunately, other markers have gone missing, some say stolen, for their metal.
RADEN DIMAANO, HEAD, SORSOGON DISASTER RISK REDUCTION AND MANAGEMENT OFFICE: We are trying to have yung ano tarp and we can use another kind of early warning or signs as long as we can establish those boundaries para mas maganda sa kanila kasi kahit ilagay lang natin tapos we have an explanation, para sa kanila rin yun, for their safety, baka hindi na mawala.
(We are trying to have tarp markers or we can use another kind of early warning as long as we can establish those boundaries. If we put markers there, as long as we explain it's for their safety, maybe they will not go missing.)
In Bulusan as in other active volcanos, establishing PDZs is the government's job, and following them is the public's.
Pia Ranada, Rappler, Sorsogon City. – Rappler.com