Redoubt Volcano, or Mount Redoubt (Dena'ina: Bentuggezh K’enulgheli), is an active stratovolcano in the largely volcanic Aleutian Range of the U.S. state of Alaska. Located at the head of the Chigmit Mountains subrange in Lake Clark National Park and Preserve, the mountain is just west of Cook Inlet, in the Kenai Peninsula Borough about southwest of Anchorage. At , in just over Mount Redoubt attains of prominence over its surrounding terrain. It is the highest summit in the Aleutian Range. In 1976, Redoubt Volcano was designated as a National Natural Landmark by the National Park Service. Active for millennia, Mount Redoubt has erupted four times since it was first observed: in 1902, 1966, 1989 and 2009, with two questionable eruptions in 1881 and 1933. The eruption in 1989 spewed volcanic ash to a height of . It caught KLM Flight 867, a Boeing 747 aircraft, in its plume. After the plane descended 13,000 feet, the pilots restarted the engines and landed the plane safely at Anchorage. The ash blanketed an area of about . The 1989 eruption is also notable for being the first ever volcanic eruption to be successfully predicted by the method of long-period seismic events developed by Swiss/American volcanologist Bernard Chouet. As of August 2015, the Alaska Volcano Observatory has rated Redoubt as Aviation Alert Level Green and Volcano Alert Level Normal. Name The official name of the mountain is Redoubt Volcano, a translation of the Russian name "Sopka Redutskaya", referring to, as does the word "redoubt", "a fortified place". A local name, "Ujakushatsch", also means "fortified place", but it is difficult to determine if one name is derived from the other. The Board on Geographic Names decided on the name "Redoubt Volcano" in 1891. The Global Volcanism Program of the Smithsonian Institution refers to the mountain simply as "Redoubt", and lists these alternate names: Burnt Mountain, Goreloi, Mirando, Ujakushatsch, Viesokaia, and Yjakushatsch. The Alaska Volcano Observatory also uses simply "Redoubt"; it lists the same alternate names in addition to: Goryalaya, Redoute Mtn., and Redutskaya, Sopka. Geology The volcano is about in diameter at its base with a rough volume of . The sides of the upper cone are relatively steep (in comparison to volcanoes in general). Made up of pyroclastic flow deposits and lava flows, and resting on Mesozoic era rocks of the Aleutian Mountain Range batholith, the mountain has been somewhat weathered by movement of