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Snowmelt-triggered earthquake swarms at the margin of Long Valley Caldera, California

March 22, 2019

Fluids are well known to influence earthquakes, yet rarely are earthquakes convincingly linked to precipitation. Weak modulation or limited data often leads to ambiguous interpretations. In contrast, here we find that shallow seismicity in the Sierra Nevada range near Long Valley Caldera is strongly modulated by snowmelt. Over 33 years, shallow seismicity rates were ~37 times higher during very wet periods versus very dry periods. Relative earthquake relocations from a swarm in 2017 reveal downward migration from ~1- to 3-km depth along a steeply inclined plane. Steeply dipping strata may provide high-permeability pathways and faulting plane. Here we combine the correlated seismicity and hydrologic time series with the propagation observed in the relatively relocated earthquakes. From this combined evidence, we infer that pressure diffusion from groundwater recharge dramatically accelerated shallow seismicity rates, causing seismic swarms unrelated to volcanic processes.

Citation Information

Publication Year 2019
Title Snowmelt-triggered earthquake swarms at the margin of Long Valley Caldera, California
DOI 10.1029/2019GL082254
Authors Emily Montgomery-Brown, David R. Shelly, Paul A. Hsieh
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Series Number
Index ID 70222523
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center