Long-Period Seismicity at Long Valley Caldera
Abstract
Monitoring seismic activity in volcanic settings is significant to assessing regional hazards and forecasting potential eruptions. Detection of long-period (LP) earthquakes, which are events characterized by an enrichment of low-frequency energy, may indicate the movement of hydrothermal or magmatic fluid within a volcanic plumbing system. Long Valley Caldera (LVC) is an active volcano in eastern California where episodes of magmatic unrest, including earthquake swarms and intermittent LP seismicity, have been observed throughout the past four decades. A decade-long inflationary episode beginning in 2011 has been interpreted as ongoing pressurization of a magma reservoir at 8 km depth. Although the depth of the reservoir is relatively well-constrained, the dynamics of magma transport, and the structures along which transport occurs, are not as well understood. Using a 21-year earthquake catalog, we analyze seismic waveform data recorded by 27 stations in the LVC region, and classify over 10,000 earthquakes as either volcano-tectonic or LP events based on their relative proportion of recorded low-frequency energy. We find that the deepest LP seismicity in this region occurs beneath Mammoth Mountain, a volcano located near the southwestern rim of the larger LVC caldera. Our results show deep (15-30 km below sea-level) LP events occurring beneath the western flank of Mammoth Mountain, and becoming shallower towards the eastern flank of the volcano. Outside of Mammoth Mountain, LP events at LVC tend to occur at shallow crustal depths (<8 km below sea-level), and are concentrated near the southern rim of the caldera. We identify a region of distributed LP seismicity between these two areas of LP seismicity. Our results highlight the potential of using LP seismicity to monitor deep magma dynamics in the LVC region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.V21B..03B