Long Valley Caldera
The Long Valley Caldera is located in the eastern part of the US state of California on the border with Nevada , in Mono County about 25 km south of Mono Lake . It is an active volcanic area that collapsed due to a violent explosive volcanic eruption 760,000 years ago on an area of 544 km² (approx. 32 km by 17 km east-west or north-south extension) and around 300 m compared to today's surroundings is sunk up to 1000 m. The Long Valley Caldera is one of the largest calderas on earth and the second largest caldera in the USA after Yellowstone . During the Plinian eruption of the supervolcano, 1400 km³ of rhyolitic ash and pyroclastics were thrown out within six days. The magma chamber of 3300 km³ to 6600 km³ still contains 900 to 1400 km³ of rhyolitic melt.
Even today, earthquakes and gas leaks frequently occur in the area of the Long Valley Caldera . In the west and north of the caldera are the active Inyo Craters , part of the Mono-Inyo Craters , which are connected to it in a volcanic manner. For this reason, the US Geological Survey maintains its own observatory, the Long Valley Observatory (LVO), to research and monitor the activity of the caldera and to be able to warn the population if there are signs of an impending eruption.
The caldera forms the upper, northern end of the Owens Valley , between the Sierra Nevada in the west and the White Mountains in the east. The Owens River and its tributary Hot Creek arise in it . Lake Crowley Reservoir on the Owens River lies entirely in the southern part of the caldera. All land, except in the settlements and on Lake Crowley, is almost entirely federally owned and belongs to the Inyo National Forest , a national forest under the administration of the United States Forest Service . Mammoth Lakes and Crestview are located in the caldera . The valley is accessed by the US highway US 395 .
Since 1941, surface water from the catchment area of Mono Lake north of the caldera has been diverted through the Long Valley Caldera south into the Owens Valley and with most of the water from its catchment area into the Los Angeles Aqueduct . It supplies the city of Los Angeles, around 450 km away, with drinking water.
In the southeast, outside the actual caldera, are the Volcanic Tablelands . The subsoil there is tuff , formed from volcanic ashes ejected from the Long Valley Caldera. The landscape with steep to vertical wall structures eroded from this rock.
Web links
- Long Valley Caldera in the Global Volcanism Program of the Smithsonian Institution (English)
- Long Valley at the USGS (English)
Individual evidence
- ^ Seismic evidence for significant melt beneath the Long Valley Caldera , GeoScienceWorld on August 2, 2018
Coordinates: 37 ° 43 ′ N , 118 ° 53 ′ W