VOLCANIC ERUPTIONS: Mount redoubt, Alaska, 1989-90. Mount redoubt, Alaska

Mount Redoubt, or Redoubt Volcano, is and active and recently eruptive stratovolcano in the largely volcanic Aleutian Range of The U.S. state of Alaska. Located in the Chigmit Mountains (a subrange of the Aleutians), the mountain is just west of Cook Inlet, in the Kenai Peninsula Borough. Mount Redoubt towers 9,000 feet (2,700 m) above the surrounding valleys. The volcano is about 3.7 miles in diameter at its base. 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 several glaciers that reside on it. The current main vent is on the north side of the crater by the head of the Drift glacier. Also present on the mountain are Holocene lahar deposits that extend as far as the Cook Inlet. This mountain has produced andesitic, basalt and dacite, with relatively silicic andesite dominant in recent eruptions. December 14th 1989

• Sudden eruption that lasted over 6 months • Sudden melting of snow and ice caused by pyroclastic flows and dome collapses caused lahars. • These lahars flowed as far as Cook Inlet 22 miles from the eruption • caused the engine failure of an aeroplane due to volcanic ash. • The eruption caused an ash cloud that blanketed an area of 7,700km2 • It was the first eruption ever to be accurately predicted. KLM flight 867

• On 15 December 1989, KLM Flight 867 en route to Narita International Airport, Tokyo from Amsterdam was descending into Anchorage International Airport, Alaska when all four engines failed. The Boeing 747-400, less than 6 months old, flew through a thick cloud of volcanic ash from Mount Redoubt, which had erupted the day before. • The eruption spewed volcanic ash to a height of 45,000 ft (14,000 m) and caught KLM Flight 867.