The basaltic shield volcano on the Island of Hawaii is among the most extensively studied volcanoes in the world. The volcano, with its summit caldera, is located on the east flank of giant Mauna Loa. Activity began with a violent explosive eruption in 1790. In the 19th and early 20th Centuries its lava lake eruptions attracted widespread attention. Nearly half of the world's known lava lake eruptions occur here.