Attenuation of P and S waves in a magma chamber in Long Valley Caldera, California

Shallow earthquakes around the southwest boundary of Long Valley caldera, west of the Hilton Creek fault, are characterized by lack of S‐waves at regional seismic network stations to the northwest, north and northeast, and P‐waves for these same station‐event combinations are deficient in frequencies higher than about 2‐3 Hz. Earthquakes east of the Hilton Creek fault and southeast of the caldera have normal P‐ and S‐wave signatures at the same stations. These effects are explained by propagation through a magma chamber in the south‐central part of Long Valley caldera, at depth greater than 7‐8 km.