← Back to Sessions

Imaging the Subsurface of Long Valley Caldera Through Converted Phases Recorded on a Distributed Acoustic Sensing Network

Description: 

The volcanic system within the Long Valley Caldera once produced the Bishop Tuff supereruption and remains active today. Thus, the region is of great scientific and societal importance, with the mapping of its subsurface crucial to a broad understanding of the system’s behavior. Tomography remains a valuable tool in subsurface imaging, but cannot adequately characterize sharp boundaries in velocity, such as those expected beneath the caldera. An understanding of such boundaries in a magmatic system is crucial both to constraining its true extent and determining changes in structure over time. Sharp features may be characterized by reflected phases, but past work on the subject has been limited by poor spatial coverage, sometimes relying on arrivals at a single channel. The recent deployment of a distributed acoustic sensing array across the caldera provides the opportunity for improved imaging of sharp features through reflection seismology. The array spans the caldera, covering approximately 90 kilometers at 10-meter channel spacing. For certain local earthquakes, the array regularly records a converted phase which has been interpreted by past work as an SP reflection generated by the roof of the large Pleistocene magma chamber located approximately at 10 km depth. Using seismicity in the vicinity of the caldera as a passive source, we image reflectors capable of producing this phase. We jointly consider the results of Kirchoff migration, as well as an inversion based solely on travel time, to delineate the top of the large magmatic chamber of this volcanic system.

Session: Understanding Earth Systems with Fiber-optic Cables [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Eli Bird

Student Presenter: Yes

Invited Presentation: 

Authors