Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Seismic investigation of magmatic unrest beneath Mammoth Mountain, California, USA

Guoqing Lin
Seismic investigation of magmatic unrest beneath Mammoth Mountain, California, USA
Geology (Boulder) (June 2013) 41 (8): 847-850

Abstract

I present a reinvestigation of the seismic activity during an 11-mo-long seismic swarm between 1989 and 1990 beneath Mammoth Mountain in eastern California (United States). This swarm, believed to be the result of a shallow intrusion of magma beneath Mammoth Mountain, was followed by the emission of magmatic CO (sub 2) gas, resulting in tree die-off in 1990 and posing a significant human health risk around Mammoth Mountain. In this study, I apply a state-of-the-art approach to estimate the ratio of compressional- to shear-wave velocity (Vp/Vs) within similar event clusters using differential times from waveform cross-correlation. A high-resolution three-dimensional seismic velocity model and a precise earthquake location catalog are obtained to complement the analysis of the in situ Vp/Vs ratios. The majority of the relocated seismicity below sea level is distributed in an anomalous body with low Vp and high Vp/Vs, consistent with the seismic expression of the magma body that triggered the seismic swarm. Abrupt changes in Vp/Vs ratios, with lower values for the shallow depths, are observed near sea level, indicating the source of the 1989 CO (sub 2) flux is a shallow CO (sub 2) reservoir instead of the hypothesized basaltic magma at mid-crustal depths of 10-25 km. From sea level to the surface, low Vp/Vs ratios in a near-vertical zone suggest involvement of fluid in the upward-migration of the seismicity.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 8
Title: Seismic investigation of magmatic unrest beneath Mammoth Mountain, California, USA
Author(s): Lin, Guoqing
Affiliation: University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, FL, United States
Pages: 847-850
Published: 20130606
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 20
Accession Number: 2013-054275
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
N37°37'60" - N37°37'60", W119°01'60" - W119°01'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201333
Close Modal

or Create an Account

Close Modal
Close Modal