1991 Mount Pinatubo Eruption In The Philippines

Mount Pinatubo is one of a chain of composite volcanoes in a part of the Philippines. Before the eruption, more than 30,000 people lived in small villages on the volcano's flanks. A much larger population, about 500,000, live in cities and villages on broad, gently sloping alluvial fans surrounding the volcano. Many of them depend on the rich soil for agricultural and subsistence farming.

In 1991, Mt Pinatubo erupted. Deposits of 5 cm or more thick covered a land area of about 4,000 sq km surrounding Pinatubo. These deposits buried crops, and the weight of the rain-saturated depeosits, no doubt with assistance from repeated intense seismic shaking and buffeting by wind, caused numerous roofs to collapse in communities around the volcano and on the two large U.S. military bases. More than 300 people died during the eruption, most of them from collapsing roofs.

Typhoon Yunya raised the death tolls further by bringing heavy rain, which saturated the accumulating deposits, and strong winds that contributed to the widespread dispersal of thick ashes. This thick blanket of ashes block the clouds and the sky thus reducing visbility, which affected incoming and outgoing flights. The thick ashes even lowered the atmosphere temperature.

Pyroclastic flows stripped vegetation from broad areas around Mount Pinatubo and partly filled valleys on all sectors of the volcano with thick hot deposits of ash and coarser fragments.

During the annual monsoon, rains generated repeated mudflows and floods, which progressively buried towns and agricultural land, destroyed homes, bridges and roads. Economic devastation and social disruption from those mudflows were severe. However, warnings provided by the authorities based on real-time analysis of data from various instruments and seismographs helped to minimize the loss of human life from the mudflows.

Generation of destructive mudflows is likely to continue for years before relatively stable drainageways are re-established. During this period, the repeated destruction of homes, farms, and structures by mudflows and the disruption of human activities caused by damage and traumatic evacuations will continue to represent the eruption's greatest social impact.

Today, Mt Pinatubo is still an active volcano, frequently billowing out smoke or showing signs of volcanic activity. However, people still choose to stay on near the volcano so as to reap benefits, especially for agriculture use, from its rich soil.