The 16 x 32 km (20 x 10 mi) Long Valley caldera east of the central Sierra Nevada Range formed as a result of the voluminous Bishop Tuff eruption (considered a "supereruption") about 760,000 years ago.

Originally, the volcano observatory was known as the Long Valley Observatory which monitored volcanic activity east of the Sierra Nevada in Mono County, California which included Long Valley Caldera, Mammoth Mountain, and the Mono–Inyo Craters.

Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.

Nov 20, 2023 · View from Lookout Mountain of Obsidian Dome and surrounding area, Long Valley Caldera. Examine a classic example of columnar lavas and learn how basalts cool to form hexagonal patterns. Examine dome rocks with a marble-cake texture that was created by the mixing of two different magmas from separate sources.

The Long Valley Observatory (LVO) of the United States Geological Survey (USGS) monitors and studies earthquakes, ground deformation, degassing, and other types of geologic unrest in and around the Long Valley caldera.

Sep 7, 2023 · This field excursion treated USGS geoscientists to expansive views of the Long Valley Caldera, Mono-Inyo Craters, Mono Lake and Sierran granite and metamorphic rocks under clear blue skies.

The Long Valley Observatory is directed by a Scientist in Charge and an assistant Scientist in Charge and operated by four team leaders. Teams that monitor activity at Long Valley Caldera are called into action whenever there is a volcanic crisis in the Long Valley area.

The Long Valley Caldera was formed by a massive volcanic eruption 760,000 years ago. The region is monitored by the Long Valley Observatory (LVO), one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety.

During periods of routine activity, the Long Valley Observatory Scientist-in-Charge (LVO SIC) acts as a coordinator and works through the appropriate line managers to coordinate monitoring, hazards assessment, and information dissemination for the Long Valley Caldera - …

The USGS California Volcano Observatory (CalVO), headquartered in Menlo Park CA, replaces the former Long Valley Observatory (LVO), which was established in 1982 to monitor the restless Long Valley Caldera and Mono-Inyo Craters region of Eastern California.