Click on the image for a bigger version. Think about it. Research this excellent website. Read these excellent case study notes. Fantastic site on Mount Pinatubo - look at pages 2 and 3. Watch the Sulphur Dioxide cloud disperse on this movie. Attempt the Venn diagram exercise below. Electricity went off, water was contaminated, road links were destroyed, and telephone links were cut. Social Effects. Economic Effects. Environmental effects.
Houses and bridges destroyed and needed replacing and Manila airport had to be closed. Volcanic ash is blown in all directions over hundreds of KMs, smothering fields and buildings. Heavy rainfall from Typhoon Yunga causes buildings to collapse.
All efforts were focused on answering the questions — will Pinatubo erupt catastrophically, and when? Volcanologists are first to admit that forecasting what a volcano will do next is a challenge. In late May, the number of seismic events under the volcano fluctuated from day-to-day. Trends in rate and character of seismicity, earthquake hypocenter locations, or other measured parameters were not conclusive in forecasting an eruption. A software program called RSAM real-time seismic amplitude measurement , developed in to keep an eye on Mount St.
Helens, helped scientists analyze seismic data to estimate the pent-up energy within Pinatubo that might indicate an imminent eruption.
The map was based on the maximum known extent of each type of deposit from past eruptions and was intended to be a worst-case scenario.
The map proved to forecast closely the areas that would be devastated on June The Clark Air Base sprawled over nearly 10, acres with its western end nestled in the lush, gently rolling foothills of the Zambales Mountains—only 9 miles 14 km east of Mount Pinatubo.
At the time, the population of Clark and nearby cities of Angeles, Sapangbato, Dau and Mabalacat numbered about , Senior base officials listened to daily briefings and put together plans to evacuate. Everyone agreed that if there were an evacuation, people must be moved to an area where they would be safe—not statistically safe, but perfectly safe.
Early June 10, in the face of a growing dome, increasing ash emission and worrisome seismicity, 15, nonessential personnel and dependents were evacuated by road from Clark to Subic Bay. By then, almost all aircraft had been removed from Clark and local residents had evacuated. Additional explosions occurred overnight and the morning of June Seismic activity during this period became intense.
The visual display of umbrella-shaped ash clouds convinced everyone that evacuations were the right thing to do. When even more highly gas-charged magma reached Pinatubo's surface June 15, the volcano exploded. The ash cloud rose 28 miles 40 km into the air.
Volcanic ash and pumice blanketed the countryside. Huge avalanches of searing hot ash, gas and pumice fragments, called pyroclastic flows, roared down the flanks of Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as feet meters thick. The eruption removed so much magma and rock from beneath the volcano that the summit collapsed to form a small caldera 1. If the huge volcanic eruption were not enough, Typhoon Yunya moved ashore at the same time with rain and high winds.
The effect was to bring ashfall to not only those areas that expected it, but also many areas including Manila and Subic Bay that did not. Fine ash fell as far away as the Indian Ocean, and satellites tracked the ash cloud as it traveled several times around the globe. With the ashfall came darkness and the sounds of lahars rumbling down the rivers.
Several smaller lahars washed through Clark, flowing across the base in enormously powerful sheets, slamming into buildings and scattering cars as if they were toys. Nearly every bridge within 18 miles 30 km of Mount Pinatubo was destroyed. Mount Pinatubo ejected millions of tons of sulfur dioxide gas into the atmosphere, forming a cloud over the earth and decreasing average worldwide temperatures by almost 1 degree Fahrenheit for several years after the eruption.
The sulfur dioxide, which mixed with water and oxygen in the atmosphere to create sulfuric acid, also contributed to a rapid destruction of ozone. The ozone layer hole over Antarctica reached its largest size when observed the year following the eruption. The volcano today is a safe place to visit. The crater of the volcano is a beautiful lake that is 2.
However it is advised not to swim in the water of the lake.
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