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Temporal and spatial variation of local stress fields before and after the 1992 eruptions of Crater Peak vent, Mount Spurr volcano, Alaska

Bulletin of the Seismological Society of America

By:
, , , and
DOI: 10.1785/0120030259

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Abstract

We searched for changes in local stress-field orientation at Mount Spurr volcano, Alaska, between August 1991 and December 2001. This study focuses on the stress-field orientation beneath Crater Peak vent, the site of three eruptions in 1992, and beneath the summit of Mount Spurr. Local stress tensors were calculated by inverting subsets of 140 fault-plane solutions for earthquakes beneath Crater Peak and 96 fault-plane solutions for earthquakes beneath Mount Spurr. We also calculated an upper-crustal regional stress tensor by inverting fault-plane solutions for 66 intraplate earthquakes located near Mount Spurr during 1991-2001. Prior to the 1992 eruptions, and for 11 months beginning with a posteruption seismic swarm, the axis of maximum compressive stress beneath Crater Peak was subhorizontal and oriented N67-76??E, approximately perpendicular to the regional axis of maximum compressive stress (N43??W). The strong temporal correlation between this horizontal stress-field rotation (change in position of the ??1/ ??3 axes relative to regional stress) and magmatic activity indicates that the rotation was related to magmatic activity, and we suggest that the Crater Peak stress-field rotation resulted from pressurization of a network of dikes. During the entire study period, the stress field beneath the summit of Mount Spurr also differed from the regional stress tensor and was characterized by a vertical axis of maximum compressive stress. We suggest that slip beneath Mount Spurr's summit occurs primarily on a major normal fault in response to a combination of gravitational loading, hydrothermal circulation, and magmatic processes beneath Crater Peak. Online material: Regional and local fault-plane solutions.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Temporal and spatial variation of local stress fields before and after the 1992 eruptions of Crater Peak vent, Mount Spurr volcano, Alaska
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120030259
Volume
94
Issue:
6
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
2366
Last page:
2379
Number of Pages:
14