フィリピン・ルソン島南部，ブルサン火山2006-2007年噴火による降下火山灰

The Bulusan volcano is one of the active volcanoes in the Philippines, and is located in southern Luzon. In 2006 and 2007, 19 and 7 distinct phreatic eruptions of the volcano occurred, respectively. Each discrete event produced tephra that was dispersed by prevailing winds mainly to the west or southwest of the summit vent, blanketing portions of the western Sorsogon Peninsula. Some events were recorded as explosion-type earthquakes. Whenever possible, fallout tephra deposits were mapped and sampled to determine the volume and composition of material produced from each eruptive event. Based on the dispersal maps, the average volume was estimated to be 10 5 m 3 . No juvenile magma were detected in ash and lithic samples by petrographic and X-ray fl uorescence analysis. Therefore, all analyzed samples were considered products of phreatic eruptions.