Report on Pinatubo (Philippines) — 8 August-14 August 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 August-14 August 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Pinatubo (Philippines). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 8 August-14 August 2001. Smithsonian Institution and US Geological Survey.
15.13°N, 120.35°E; summit elev. 1486 m
All times are local (unless otherwise noted)
Several news reports stated that rising water in Pinatubo's crater is now approaching dangerous levels. If the water exceeds the crater lip, it could cause the crater to partially collapse and water could inundate the town of Botolan. The town is 40 km NW of the volcano and has 46,000 residents. In recent weeks the water surface has risen from ~6.4 to 5 m below the crater lip. Scientists are worried that the intense rain during the current rainy season will cause the water level to continue to rise. In the next few weeks, with oversight by Philippine officials and geologists, local residents will dig a 5-m notch in the side of the crater that will drain the water away from inhabited areas.
Geologic Background. Prior to 1991 Pinatubo volcano was a relatively unknown, heavily forested lava dome complex located 100 km NW of Manila with no records of historical eruptions. The 1991 eruption, one of the world's largest of the 20th century, ejected massive amounts of tephra and produced voluminous pyroclastic flows, forming a small, 2.5-km-wide summit caldera whose floor is now covered by a lake. Caldera formation lowered the height of the summit by more than 300 m. Although the eruption caused hundreds of fatalities and major damage with severe social and economic impact, successful monitoring efforts greatly reduced the number of fatalities. Widespread lahars that redistributed products of the 1991 eruption have continued to cause severe disruption. Previous major eruptive periods, interrupted by lengthy quiescent periods, have produced pyroclastic flows and lahars that were even more extensive than in 1991.
Sources: Associated Press, Philippine Institute of Volcanology and Seismology (PHIVOLCS), Reuters, Disaster Relief.org