HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Electronic Supplement Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Roman, D. C. Articles by Cashman, K. V. Search for Related Content GeoRef GeoRef Citation

Temporal and Spatial Variation of Local Stress Fields before and after the 1992 Eruptions of Crater Peak Vent, Mount Spurr Volcano, Alaska

¹ Department of Geological Sciences
University of Oregon
1272 University of Oregon
Eugene, Oregon 97403-1272
 (D.C.R., K.V.C.)

² U.S. Geological Survey
Cascades Volcano Observatory
1300 SE Cardinal Court, Bldg. 10
Vancouver, Washington 98683
 (S.C.M.)

³ U.S. Geological Survey
Alaska Science Center
Alaska Volcano Observatory
4200 University Drive
Anchorage, Alaska 99508
 (J.A.P.)

^* Present address: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom; droman{at}earth.leeds.ac.uk.

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.

This article has been cited by other articles:

				D. H. von Seggern, K. D. Smith, and L. A. Preston Seismic Spatial-Temporal Character and Effects of a Deep (25-30 km) Magma Intrusion below North Lake Tahoe, California-Nevada Bulletin of the Seismological Society of America, June 1, 2008; 98(3): 1508 - 1526. [Abstract] [Full Text] [PDF]

				D. C. Roman and K. V. Cashman The origin of volcano-tectonic earthquake swarms Geology, June 1, 2006; 34(6): 457 - 460. [Abstract] [Full Text] [PDF]