Mount Pinatubo

Mt Pinatubo trekking - panoramio (5)

Mount Pinatubo Relief Map, SRTM-1

Philippine Island - Luzon Island - NARA - 68156975

Pre-eruption Pinatubo

Pinatubo91eruption plume

Eruption of Mount Pinatubo, June 15, 1991

Mount Pinatubo is a volcano located on the island of Luzon in the Philippines. It is part of a chain of volcanoes along the Luzon Volcanic Arc, which is the result of the Philippine Mobile Belt colliding with the Eurasian Plate. The volcano's eruption in 1991 was one of the largest volcanic eruptions of the 20th century and had significant global environmental and economic impacts.

Geography and Geology

Mount Pinatubo is situated near the tripoint of the provinces of Pampanga, Tarlac, and Zambales. Before its 1991 eruption, it was an inconspicuous volcano, unknown to most people even in the Philippines. The area surrounding the volcano is a mix of mountainous terrain covered in dense forests, with valleys and rivers that were drastically altered by the eruption's aftermath.

The geology of Mount Pinatubo consists of andesite and dacite, which are types of volcanic rock that indicate the volcano's explosive potential. Prior to the 1991 eruption, Pinatubo was dormant for about 500 years, with its last major eruption occurring around 1500 AD.

1991 Eruption

The 1991 eruption of Mount Pinatubo was preceded by a series of earthquakes and small phreatic explosions, signaling the reawakening of the volcano. Scientists, including those from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and the United States Geological Survey (USGS), monitored the volcano's activity closely, leading to the timely evacuation of thousands of people from surrounding areas.

On June 15, 1991, Mount Pinatubo explosively erupted, ejecting more than 5 cubic kilometers of material. The eruption column reached high into the atmosphere, spreading ash over much of Luzon and causing widespread darkness in the middle of the day. The eruption produced significant pyroclastic flows, lahars, and a large volcanic ash cloud that had extensive effects on global climate, including a decrease in average global temperatures.

Impact

The eruption had devastating effects on the Philippines, including the destruction of homes, the displacement of thousands of people, and the disruption of agriculture and infrastructure. The ash fall damaged crops, buildings, and machinery, while lahars, triggered by heavy rains in the months following the eruption, buried communities and farmlands under thick mudflows.

Globally, the eruption had a significant impact on the climate, leading to a temporary cooling of the Earth's surface. The sulfur dioxide (SO2) emitted into the stratosphere formed sulfuric acid aerosols, which reflected sunlight away from the Earth and led to a decrease in global temperatures by about 0.5 degrees Celsius.

Post-Eruption Recovery and Monitoring

In the years following the eruption, efforts were made to rebuild the affected communities and manage the ongoing threat of lahars. Dams and channels were constructed to divert mudflows away from populated areas. The ecosystem around Mount Pinatubo has been gradually recovering, with vegetation reestablishing itself and wildlife returning to the area.

Mount Pinatubo remains under close observation by PHIVOLCS, with monitoring stations around the volcano to detect signs of activity. The 1991 eruption serves as a reminder of the potential hazards of living in close proximity to active volcanoes and the importance of volcanic monitoring and preparedness.