Pinatubo 1991 Case Study

The 1991 Pinatubo Eruption

Introduction

From June 12-16, 1991 Mount Pinatubo, a stratovolcano (now stratovolcanic caldera) in the Phillipines, erupted killing over 350 people (847 in total, after the eruption) (USGS). It is considered the largest eruption to affect a larger population. It started with magma rising building a lava dome (Chatterjee M., 2007) that had built up over years from extruding, viscous lava. This dome later exploded when a magma rich in gas reached the surface. This paper will include a description of the sequence of events, explain why this particular eruption was so catastrophic, and what is currently being done to prevent it happening again.

Sequence of Events

M. R. Chatterjee’s article on the eruption, published in 2007, describes the dates

The reason why it was so damaging was because it happened at the same time Typhoon Yunya hit. The heavy rain was able to mix well with the thick ash deposits creating a dense material that either settled on roof tops or formed lahars. Both of these products made buildings collapse, killing people stuck inside. Agriculture, including livestock and rice farms, were destroyed for nearly €25 million. Reforestation was interrupted as everything got covered in ash. In addition to damaging and destroying thousands of houses, power lines and roads were also damaged by the pyroclastic flows and lahars. It is difficult to set a precise number to the cost of damages because there were so many areas affected - schools, military facilities (from the US air base), roads, houses, agriculture, health issues, and new jobs for the evacuated people, etc. However, the costs came close to $700 million. The eruption had a significant impact on humans, but it also affected the climate. Aerosols released from the volcano can partly block sunlight by reflecting the rays. This led to a global decrease in temperature of 0.4°C (Self et al.,