The second-largest volcanic eruption of the last century, and by far the largest eruption to affect a densely populated area, occurred at Mount Pinatubo in the Philippines on June 15, 1991. The impacts of the eruption continue to this day. The eruption produced high-speed avalanches of hot ash and gas, giant mudflows, and a cloud of volcanic ash hundreds of miles across.
April 2 nd 1991 First rumblings after 450 years. Small amount of ash thrown up to 800 metres in the air For next 2 months small tremors were recorded in the volcano. Events leading up to the eruption
June 3 rd 1991 Pinatubo ejects ash which lasts for 30 minutes. Up to 2,000 quakes a day, some suggesting that the magma was getting near the surface.
Sunday June 9 th 1991 Ash and steam ejected from the volcano for 8 hours. Pyroclastic flows reached 5km from the crater.
Wednesday June 12 th 1991 At 8.51 a.m. three major explosions sent a mushroom shaped cloud over 20km into the air. Ash, pumice and other fragments were ejected. Rivers overflowed due to pyroclastic flows. Around midnight more explosions sent ash 25 km into the atmosphere.
Thursday June 13 th 1991 Another violent eruption created further ash falls covering three settlements. Winds carried the ash hundreds of kilometres in all directions.
Friday June 14 th 1991 The fourth major eruption happened at 1.09 p.m. Ash went 25 km above the vent. At 3.30 p.m. a much bigger eruption sent a cauliflower-shaped cloud of volcanic debris 30 km into the air. Major pyroclastic flows reached 15km from the volcano. Smaller eruptions at 6.35 pm, 10.18 pm and 11.21 pm.
Saturday June 15 th 1991 Two eruptions occurred at dawn which caused a pyroclastic flow travelling at 80 kph. Seven more eruptions caused an ash cloud 18 km wide and 25 km high. Pyroclastic flows reach 16 km from the volcano. At 10.27 a.m. a violent eruption forced debris up 40 km into the air. Five similar eruptions quickly followed. Over 19 eruptions during the day!
847 people killed. 184 injured. 23 missing presumed dead. 1.18 million people affected Houses and public buildings collapsed from weight of ash deposits. 650,000 workers forced out of work due to destruction of farms, shops and factories. America had to evacuate their Air Force Base. Volcanic dust blanketed towns. Public buildings had to be used for evacuation centres to accommodate refugees from devastated area.
Planning <ul><li>Volcanic eruptions are not preventable but planning and preparation can drastically reduce death tolls and limit damage </li></ul><ul><li>Volcanoes can be preceded by gas emissions this helps understand when they are going to erupt. </li></ul><ul><li>The evacuation of villages around Pinatubo saved lives </li></ul><ul><li>The problem was that the evacuation centers lacked sanitation this resulted in a loss of life through the spread of disease </li></ul>
PHILVOLCS and USGS <ul><li>Seismic testing by USGS and PHILVOLCS located earthquakes which gave adequate warning </li></ul><ul><li>S02 levels were also found to be very high another indicator of imminent eruption </li></ul><ul><li>A hazard map was completed to aid evacuation </li></ul>
Evacuation <ul><li>5 th April villages within 10km of summit evacuated </li></ul><ul><li>12 th April evacuation area extended to 30km and 200,000 people evacuated </li></ul><ul><li>Some Aeta people refused to leave the mountain due to a lack of understanding about the eruption </li></ul><ul><li>Aeta people died in evacuation centres as they refused to take medicines </li></ul>