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Dilational processes accompanying earthquakes in the Long Valley Caldera

January 1, 2000

Regional distance seismic moment tensor determinations and broadband waveforms of moment magnitude 4.6 to 4.9 earthquakes from a November 1997 Long Valley Caldera swarm, during an inflation episode, display evidence of anomalous seismic radiation characterized by non-double couple (NDC) moment tensors with significant volumetric components. Observed coseismic dilation suggests that hydrothermal or magmatic processes are directly triggering some of the seismicity in the region. Similarity in the NDC solutions implies a common source process, and the anomalous events may have been triggered by net fault-normal stress reduction due to high-pressure fluid injection or pressurization of fluid-saturated faults due to magmatic heating.

Publication Year 2000
Title Dilational processes accompanying earthquakes in the Long Valley Caldera
DOI 10.1126/science.288.5463.122
Authors Douglas S. Dreger, Hrvoje Tkalcic, M. Johnston
Publication Type Article
Publication Subtype Journal Article
Series Title Science
Index ID 70022809
Record Source USGS Publications Warehouse