Long Valley Volcanic Center
- Current Update, last updated Jan 12, 2012 17:46 PST:
Fifteen earthquakes with magnitudes between M=1.0 and M=1.8 occurred in the Mammoth Lakes-Long Valley region in the last seven days. The events were located in the Sierra Nevada, with the exception of three earthquakes in the caldera east of the town of Mammoth Lakes and one event in Round Valley.
- Volcanic History Overview: The large 17 x 32 km Long Valley caldera east of the central Sierra Nevada Range formed as a result of the voluminous Bishop Tuff eruption about 760,000 years ago. Resurgent doming in the central part of the caldera occurred shortly afterwards, followed by rhyolitic eruptions from the caldera moat and the eruption of rhyodacite from outer ring fracture vents, with the last intracaldera eruptions about 50,000 years ago. During early resurgent doming the caldera was filled with a large lake that left strandlines on the caldera walls and the resurgent dome island; the lake eventually drained through the Owens River Gorge. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation, seismicity, and other unrest in recent years. The late-Pleistocene to Holocene Inyo Craters cut the NW topographic rim of the caldera in 1350 AD, and along with Mammoth Mountain on the SW topographic rim, are west of the structural caldera and are chemically and tectonically distinct from the Long Valley magmatic system. The most recent activity in the area was about 300 years ago in Mono Lake.
- Location: Western US, CA
Elevation: 2204 m
Recent Eruption: 300 years ago in Mono Lake
- Hazard Assessments: Miller, C. Dan; Mullineaux, D. R.; Crandell, D. R.; Bailey, R. A., 1982, Potential hazards from future volcanic eruptions in the Long Valley-Mono Lake area, east-central California and southwest Nevada; a preliminary assessment, USGS Circular 877, 10 p. :ill., maps.
- Link to monitoring data: LVO Web Site
Volcanic Alert Level: NORMAL Aviation Color Code: GREEN