Deep fluid pathways beneath Mammoth Mountain, California, illuminated by migrating earthquake swarms.

Hotovec-Ellis, Alicia J; Shelly, David R; Hill, David P; Pitt, Andrew M; Dawson, Philip B; Chouet, Bernard A · Sci Adv · 2018

basic_science · Level V

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Abstract

Although most volcanic seismicity is shallow (within several kilometers of the surface), some volcanoes exhibit deeper seismicity (10 to 30+ km) that may reflect active processes such as magma resupply and volatile transfer. One such volcano is Mammoth Mountain, California, which has also recently exhibited high rates of CO<sub>2</sub> discharge at the surface. We perform high-resolution earthquake detection and relocation to reveal punctuated episodes of rapidly propagating seismicity at mid-crustal depths along a narrow fracture zone surrounding a body of partial melt. We infer that these earthquakes track dike intrusions or fluid pressure pulses associated with CO<sub>2</sub> exsolution, suggesting that the deep plumbing system of Mammoth Mountain is an active conduit for fluid transport from the base of the crust to the surface.