Situated on the western fringes of the Pacific Ring of Fire, the Philippines experiences frequent seismic and volcanic activity. The Benham Plateau to the east in the Philippine Sea is an undersea region active in tectonic subduction. Around 20 earthquakes are registered daily, though most are too weak to be felt. The last major earthquake was the 1990 Luzon earthquake. There are many active volcanoes such as the Mayon Volcano, Mount Pinatubo, and Taal Volcano. The eruption of Mount Pinatubo in June 1991 produced the second largest terrestrial eruption of the 20th century. The Philippines is the world's second-biggest geothermal energy producer behind the United States, with 18% of the country's electricity needs being met by geothermal power.