GEOL 106 Lecture Notes - Subduction, Mount Unzen, Lake Nyos
Document Summary
Ash on flanks of volcano mix with melted snow; flow down steep sides of volcano and river valleys over distances greater than 100 km. Ex navado del ruiz (1985), more than 20,000 died. Mt st helens (1980), mount unzen (1991), mount rainier. Only occurs when volcanoes are out at sea (island arcs) Co2 can settle in low-laying areas around volcano and suffocate living things (ex lake nyos 1986) Tsunami hit crete and ash cloud blew over. Can have global catastrophic effects (climate and weather effects) Supereruptions: greater than 1000-5000 cubic km of volcanic ash deposits. They probably present the greatest natural hazard to mankind in terms of the severity and longevity of the impact the ultimate geological hazard . Assessing the volcanic risk of an area: understand the hazard. Locate and determine the nature of volcanoes in the area. Located at convergent (subduction zones) and divergent plate margins, and hot spots.