Mount Pinatubo is located in the Philippines on an island called Luzon, it is an active volcano and classified as a stratovolcano. It is tall with steep sides formed from layers and layers of volcanic ash which forms Pumice and hardened lava. The most recent eruption of June 15, 2014 was one of the largest eruptions of the 20th century. The eruption in 1991 created a ash cloud that covered an area of more than hundred thousand square kilometers, which put the island into a darkness. This eruption was about ten times more powerful than the eruption of Mt. St. Helens in 1980. Thousands were evacuated but eight hundred people were killed during the eruption. At the same time of the eruption in 1991 a Typhoon (Yunya) was affecting the Philippines at the same time, which made things worse for the people in Luzon. The US Air Force had two bases on the island of Luzon – Clark Air Base and Subic Naval Base, following the eruption the Clark Air Base has been abandoned and is now controlled by Philippine forces. The eruption formed a crater lake called Lake Pinatubo, and it is thought that an eruption of Mount Pinatubo about 35000 years ago was much larger than the 1991 eruption.