Six-component continuous monitoring of seismic swarms and other earthquakes in the region of Long Valley Caldera, California


Grant No.:


Grant Agency:

Ministry of Education, Youth and Sports (MEYS, MŠMT in Czech)

Resolved in:

2019 - 2022

Principal investigator:

Dr. Jiří Málek
Institute of Rock Structure and Mechanics of the CAS


Long Valley Caldera in California is an elliptical depression (about 15x30 km) on the eastern slopes of the Sierra Nevada. It is followed by a chain of rhyolite volcanic craters, which reaches Mono Lake in the north. This area, interwoven with a number of declining tectonic faults (with a predominant eastern slope), is characterized by recurrent seismic swarms, episodes of soil uplifts, CO2 emissions of magmatic origin and strong geothermal activity, which may indicate a gradual recovery of volcanic activity. The caldera itself was formed during a cataclysmic eruption 760 thousand years ago. During multiple eruptions between 220 and 50,000 years ago, a new crater was created on the northern edge of the caldera, the Mammoth Mountains, and later a chain of craters in the northern part. During the last 5,000 years, there have been repeated minor to moderate eruptions in the area at intervals of hundreds of years. In recent decades, seismic swarms have been typical for the area, which contain mixed earthquakes, from pure shear earthquakes to earthquakes with a strong non-shear component. Furthermore, tectonic earthquakes with a aftershock sequence are also observed here, including deep earthquakes in the central part of the Sierra Nevada mountains. The occurrence of these phenomena and especially the proximity of their foci to the decline fault system at the eastern edge of the Sierra Nevada mountains can be explained by the significant interaction between phenomena of volcanic and tectonic origin. Earthquake and volcanic activity in this area reflects long-lasting and very complex relationships between tectonic and magmatic processes in the Earth's crust and upper mantle. These relationships are the focus of geoscience research conducted here in the last three decades. The presented project could significantly contribute to their deeper understanding.


U.S. Geological Survey

ISVAV: (What is it?)

Project in The Research and Development and Innovation System of the Czech Republic (in Czech only)

Materials for download:

Results of the 2019 Call for proposals of the Czech - American scientific cooperation