Volcano Hazards - 9 of 8
Volcano Hazards FAQs - 8 Found
Lahars can be of any size. They may be as small as several centimeters wide and deep, flowing less than one meter per second. Steep, unvegetated slopes during a heavy rain are often good sites to observe such small flows. At the other extreme, they can be a few hundred meters wide, tens of meters deep, flow at several tens of meters per second, and travel over 100 kilometers from a volcano. Such catastrophic lahars are triggered by volcanic eruptions or by massive landslides such as the one that occurred on May 18, 1980, at Mount St. Helens volcano. -- From: Brantley and Power, 1985, Reports from the U.S. Geological Survey's Cascades Volcano Observatory at Vancouver, Washington: Earthquake Information Bulletin, v.17, n.1, January-February 1985.