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New Fact Sheet Explains Recent Geysering and other Thermal Instabilities in Hot Creek, CA

Hot Creek showing new area of active boiling.

USGS scientists along with our colleagues at the U.S. Forest Service have published a new Fact Sheet, Boiling Water at Hot Creek - The Dangerous and Dynamic Thermal Springs in California's Long Valley Caldera. The Fact Sheet was written in response to safety concerns regarding recent hot spring activity and geysering in Hot Creek Gorge. Due to the unpredictability of the hazardous spring activity, the U.S. Forest Service has closed parts of the Hot Creek Geologic Site. Fact Sheet 2007-3045 explains why the previously popular swimming area is thermally unstable.

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Additional USGS Monitoring at Long Valley Caldera

Topical Studies at Long Valley Caldera

Fact Sheets (2 pages) about Long Valley Caldera

References about Long Valley Caldera


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Long Valley Caldera at a Glance

The Caldera. Long Valley Caldera a 15- by 30-km oval-shaped depression located 20 km south of Mono Lake along the east side of the Sierra Nevada in east-central California. This area of eastern California has produced numerous volcanic eruptions over the past 3 million years, including the massive caldera-forming eruption 760,000 years ago. The most recent eruption occurred just 250 years ago in Mono Lake at the north end of Mono-Inyo Craters volcanic chain.

Volcanic Unrest. In May of 1980, a strong earthquake swarm that included four magnitude 6 earthquakes struck the southern margin of Long Valley Caldera associated with a 25-cm, dome-shaped uplift of the caldera floor. These events marked the onset of the latest period of caldera unrest that continues to this day. This ongoing unrest includes recurring earthquake swarms and continued dome-shaped uplift of the central section of the caldera (the resurgent dome) accompanied by changes in thermal springs and gas emissions.

USGS Monitoring. In 1982, the U.S. Geological Survey under the Volcano Hazards Program began an intensive effort to monitor and study geologic unrest in Long Valley caldera. The goal of this effort is to provide residents and civil authorities in the area reliable information on the nature of the potential hazards posed by this unrest and timely warning of an impending volcanic eruption, should it develop. Most, perhaps all, volcanic eruptions are preceded and accompanied by geophysical and geochemical changes in the volcanic system. Common precursory indicators of volcanic activity include increased seismicity, ground deformation, and variations in the nature and rate of gas emissions.

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Other U.S. Geological Survey geology and volcano websites
| Volcano Hazards Program | Geologic Information |
| Alaska Volcano Observatory | Cascades Volcano Observatory |
| Hawaiian Volcano Observatory | Yellowstone Volcano Observatory |

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U.S. Geological Survey, 345 Middlefield Rd., MS 977, Menlo Park, CA 94025
Maintained by: Long Valley Web Team
Last modified: 3 July 2007 (dyv)