The clock is ticking

To date it has proved extremely difficult to forecast when a particular volcano is going to erupt. In the case of Pinatubo we knew a few days beforehand that there was a high risk of eruption. The scale and seriousness of the eruption were not forecasted, however. The challenge is therefore to draw up, for these regions, a kind of 'scenario' of what could happen if a certain volcano were to erupt. It is important to know what kind of eruption can be expected and what areas are potentially threatened by various kinds of volcanic dangers, such pyroclastic flows, lava flows and lava domes, lahars or volcanic mudflows, and tephra fall or ash rain.

Will it be violent?

Depending on the type of volcano, various kinds of eruption are possible, ranging from the very explosive to those on Hawaii where the lava flow is relatively calm. Most of the volcanoes in the Philippines are of the explosive variety and consequently pose a serious potential risk to the environment.
It is difficult to say what kind of volcanic hazard could be faced. In most cases it is a combination of various hazards. The assumption is that future eruptions will be of the same type as past eruptions. Descriptions of previous eruptions are often to be found in reports or other historical documents. But in most cases these descriptions do not make it possible to identify what kind of eruption took place and when, and a detailed field study by geologists and volcanologists is necessary before this can be ascertained. Modern carbon and other dating methods allow us to determine when an eruption took place.

In this study, hazard zonation maps is drawn up for the Bulusan volcano, for various types of eruption.