Mount Vsevidof (/ˌvɪzəˈviːdɒf/ or /vəˈʃeɪvɪdɒf/; Russian: Вулкан Всевидова) is a stratovolcano in the U.S. state of Alaska. Its summit is the highest point on Umnak Island, one of the eastern Aleutian Islands. Its symmetrical cone rises abruptly from its surroundings. The base of the volcano is around 10 km (6 mi) wide, steepening from about 15 degrees at 300 m (980 ft) altitude to around 30 degrees near the summit. Some glacial tongues have cut through narrow canyons up to 120 m (390 ft) deep, due to ice filling the crater and extending down the north and east flanks of the cone. Vsevidof's most recent eruption was caused by an earthquake on March 9, 1957. The mountain erupted on March 11, 1957, and the eruption ended the next day.