time and adds $5,500 to $6,000 in extra fuel costs. Cleveland has therefore been assessed by the United States Geological Survey as "a volcano with a high aviation threat score and no real-time ground based monitoring at the present time". See also List of mountain peaks of Alaska List of volcanoes in the United States References External links Cleveland eruption updates. Alaska Volcano Observatory. Active volcanoes Stratovolcanoes of the United States Volcanoes of Alaska Landforms of Aleutians West Census Area, Alaska Islands of Four Mountains 21st-century volcanic events Volcanoes of Unorganized Borough, Alaska Holocene stratovolcanoes