Long-period earthquakes in the Long Valley Caldera Region, eastern California

Andrew M. Pitt; David P. Hill

doi:10.1029/94gl01371

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Long-period earthquakes in the Long Valley Caldera Region, eastern California

Andrew M. Pitt·David P. Hill

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Abstract

Most earthquakes occurring near Long Valley caldera since the onset of recurring swarm activity in 1980 have the broad-band signature typical of tectonic or volcano-tectonic earthquakes with impulsive, high-frequency P and S waves. With the Mammoth Mountain earthquake swarm in mid 1989, we began detecting occasional events with a marked deficiency in energy above 5 Hz, a feature typical of long-period (LP) volcanic earthquakes. These events occur beneath the southwest flank of Mammoth Mountain at focal depths ranging from 10 to 28 km, distinctly deeper than the 2- to 10-km depth range for tectonic earthquakes in the area. The LP events occur at intervals ranging from weeks to months. Individual occurrences typically consist of several events within 2 to 5 minutes where the largest event has never been first. Magnitudes range from 0.5 to 1.8. The mid-crustal focal depths of the LP events are similar to occurrences at a number of areas with Holocene volcanism in Japan and the western United States. They may indicate the movement of magmatic fluids but do not necessarily indicate an imminent volcanic eruption.

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Geophysical Research Letters Article

Source-reported bounding extent: 37.61659398787745° to 37.790058096479925° latitude; -119.06651991676378° to -118.75652144550818° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

Andrew M. Pitt, David P. Hill. 2012-12-07. Long-period earthquakes in the Long Valley Caldera Region, eastern California. https://doi.org/10.1029/94gl01371

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