What is Long Valley Caldera?
[[File:Long Valley caldera NE rim.jpg|thumb|280px|Long Valley]] [[File:CalderaRelief large.png|thumb|280px|Map of the Long Valley Caldera]] '''Long Valley Caldera''' is a depression in east [[California]] next to [[Mammoth Mountain]]. The valley is one of the Earth's largest [[caldera]]s, the result of a gigantic [[volcanic eruption]]. The valley is about {{convert|20|mi}} long (east-west), {{convert|11|mi}} wide (north-south), and up to {{convert|3000|ft}} deep. Long Valley formed 760,000 years ago when a [[supervolcano|supervolcanic]] eruption released very hot ash that later cooled to form the [[tuff|Bishop tuff]] that is common to the area. The eruption emptied the [[magma|magma chamber]] under the area, so it collapsed. The second phase of the eruption released [[pyroclastic flow]]s that burned and buried thousands of square miles. Ash from this eruption blanketed much of the [[Western United States|western part]] of what is now the [[United States]]. It is not expected to explode again in such a manner. The explosion released 600 [[cubic kilometre]]s (140 cu mi) of material from vents inside the margin of the caldera. By way of comparison, the 1980 [[Mount St. Helens]] eruption released 1.2 cubic kilometres (0.29 cu mi). This eruption had a [[Volcanic Explosivity Index]] (VEI) of 7. In April 2006, three members of the Mammoth Mountain Ski Area ski patrol died while on duty. All three died from suffocation by [[carbon dioxide]] when they fell into a [[fumarole]] on the slopes of the mountain while attempting to fence it off.<ref>{{cite web |last= Covarrubias |first= Amanda |author2=Doug Smith |title= 3 Die in Mammoth Ski Patrol Accident |publisher= [[Los Angeles Times]] |date=2006-06-07 |url= http://articles.latimes.com/2006/apr/07/local/me-mammoth7 |access-date= 2013-01-08}}</ref> == References == {{reflist}} [[File:Long Valley Caldera cross section.gif|thumb|upright=1.6|Cross-section through Long Valley]] [[Category:Calderas]] [[Category:Volcanoes of the United States]] [[Category:VEI-7 volcanoes]]