Mount Pinatubo is an active stratovolcano located on the island of Luzon near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located within the Cabusilan Mountains. Before the terrestrial eruption of 1991, the areas on Pinatubo were heavily eroded with deep forests.
On July 6, 1990, there was a magnitude 7.7 earthquake that shook the mountain and the areas surrounding it. On March 5, 1991, Earthquakes were felt again from the northwestern side of the mountain. These earthquakes kept getting more intense as the weeks went on. It’s looking like some volcanic activity now. On April 2, there was what is called a phreatic eruption (which is an eruption of steam, ash, and rock, but no lava) near the 0.93 mile long fissure. Within the next few weeks, small earthquakes occurred daily. Volcanologists noticed that the amount of sulfur dioxide in the air had increased dramatically. They found out that the magma chamber had been blocked somehow, which would lead to a pressure build up in the chamber. If too much pressure built up, this would end up as an explosive eruption. On June 3, there was the first small magmatic eruption, but no explosion. On June 7, there was an explosion from the volcano, which built up an ash column reaching 4.3 miles high. The explosion made a huge crater called a caldera.
Then, on June 15, 1991, a Plinian/ Ultra-Plinian (very explosive) eruption occurred. There was one last problem; Typhoon Yunya. Typhoon Yunya was due to arrive while the eruption was occurring, making a lethal mix of rain and ash. The areas surrounding the volcano were destroyed due to ash deposits and pyroclastic flows. Luckily many people were evacuated. Lahars were created because of wet ash and heavy rain (lahars are volcanic mudflows). The volcano ejected 2.4 cubic miles of magma, and 22,000,000 short tons of metals and minerals. Pinatubo injected large amounts of aerosol into the stratosphere, more than any eruption since Krakatoa-1883. The aerosols formed a sulfuric acid haze, making global temperatures drop 0.9 degrees Fahrenheit. The total volume of the pyroclastic flows deposited around the volcanoes was 6 cubic miles. Volcanologists believe that the 1990 earthquake led to the eruption in 1991. Because Pinatubo is an active volcano today, it is still being monitored by volcanologists everywhere.
On July 6, 1990, there was a magnitude 7.7 earthquake that shook the mountain and the areas surrounding it. On March 5, 1991, Earthquakes were felt again from the northwestern side of the mountain. These earthquakes kept getting more intense as the weeks went on. It’s looking like some volcanic activity now. On April 2, there was what is called a phreatic eruption (which is an eruption of steam, ash, and rock, but no lava) near the 0.93 mile long fissure. Within the next few weeks, small earthquakes occurred daily. Volcanologists noticed that the amount of sulfur dioxide in the air had increased dramatically. They found out that the magma chamber had been blocked somehow, which would lead to a pressure build up in the chamber. If too much pressure built up, this would end up as an explosive eruption. On June 3, there was the first small magmatic eruption, but no explosion. On June 7, there was an explosion from the volcano, which built up an ash column reaching 4.3 miles high. The explosion made a huge crater called a caldera.
Then, on June 15, 1991, a Plinian/ Ultra-Plinian (very explosive) eruption occurred. There was one last problem; Typhoon Yunya. Typhoon Yunya was due to arrive while the eruption was occurring, making a lethal mix of rain and ash. The areas surrounding the volcano were destroyed due to ash deposits and pyroclastic flows. Luckily many people were evacuated. Lahars were created because of wet ash and heavy rain (lahars are volcanic mudflows). The volcano ejected 2.4 cubic miles of magma, and 22,000,000 short tons of metals and minerals. Pinatubo injected large amounts of aerosol into the stratosphere, more than any eruption since Krakatoa-1883. The aerosols formed a sulfuric acid haze, making global temperatures drop 0.9 degrees Fahrenheit. The total volume of the pyroclastic flows deposited around the volcanoes was 6 cubic miles. Volcanologists believe that the 1990 earthquake led to the eruption in 1991. Because Pinatubo is an active volcano today, it is still being monitored by volcanologists everywhere.