weeks; Unalaska (73 miles northeast) was repeatedly dusted with ash and flights into and out of this major fishing hub were frequently disrupted; floating rafts of scoria and low visibility prompted the Coast Guard to close Umnak Pass to marine traffic; and the Bering Pacific cattle ranch on the flanks of Okmok was periodically evacuated, once during noon-time darkness caused by heavy ashfall. The eruption ended in August 2008. It had a VEI of 4, giving it a rating of "cataclysmic." No lava flow was reported in this eruption, though the volcano has issued flows in the past. The eruption took place at a new vent in the northeast part of the caldera, creating a roughly 800 ft high cone, dramatically altering caldera hydrology, and discharging huge lahars, or volcanic mudflows, running from the caldera to the coast. In contrast, all 20th-century eruptions were from a cone near the southern rim of the caldera. The 2008 eruption was by far the largest eruption at Okmok since at least the early 13th century. References External links Google Earth view Volcanoes of the Alaska Peninsula and Aleutian Islands-Selected Photographs "Sulfur Dioxide from Okmok Volcano", JPL/NASA image Okmok Volcano Ash Cloud Photo page of the Okmok Volcano ash could, July 22, 2008 Okmok Volcano on Volcano Discovery Shield volcanoes of the United States Active volcanoes Landforms of Aleutians West Census Area, Alaska Mountains of Alaska Volcanoes of Alaska VEI-6 volcanoes Calderas of Alaska Volcanic crater lakes Subduction volcanoes 21st-century volcanic events Umnak Mountains of Unorganized Borough, Alaska Volcanoes of Unorganized Borough, Alaska Polygenetic shield volcanoes Pleistocene shield volcanoes Holocene shield volcanoes Pleistocene calderas Holocene calderas