Seismic image of the Mount Spurr magmatic system

Bulletin of Volcanology
By: , and 



The three-dimenisonal P-wave velocity structure of Moutn Spurr is determined to depths of 10km by tomographic inversion of 3754 first-arriving P-wave times from local earthquakes recorded by a permanent network of 11 seismographs. Results show a prominent low-velocity zone extending from the surface to 3-4km below sea level beneath the southeastern flank of Crater Peak, spatially coincident with a geothermal system. P-wave velocities in this low-velocity zone are approximately 20% slower than those in the shallow crystalline basement rocks. Beneath Crater Peak an approximately 3km-wide zone of relative low velocities correlates with a near-vertical band of seismicity, suggestive of a magmatic conduit. No large low-velocity zone indicative of a magma chamber occurs within the upper 10km of the crust. These observations are consistent with petrologic and geochemical studies suggesting that Crater Peak magmas originate in the lower crust or upper mantle and have s short residence time in the shallow crust. Earthquakes relocaetd using the three-dimensional velocity structure correlate well with surface geology and other geophysical observations; thus, they provide additional constraints on the kinematics of the Mount Spurr magmatic system.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Seismic image of the Mount Spurr magmatic system
Series title Bulletin of Volcanology
DOI 10.1007/s004450050214
Volume 60
Issue 1
Year Published 1998
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Bulletin of Volcanology
First page 27
Last page 37