A volcano bursting at the seams: Inflation, faulting, and eruption at Sierra Negra volcano, Galápagos
- William W. Chadwick, Jr.1,
- Dennis J. Geist2,
- Sigurjón Jónsson3,
- Michael Poland4,
- Daniel J. Johnson*5 and
- Charles M. Meertens6
- 1Oregon State University–National Oceanographic and Atmospheric Administration, 2115 SE OSU Drive, Newport, Oregon 97365, USA
- 2Geological Sciences, University of Idaho, Moscow, Idaho 83844, USA
- 3Institute of Geophysics, ETH Zürich, Schafmattstrasse 30, 8093 Zürich, Switzerland
- 4Hawaii Volcano Observatory, U.S. Geological Survey, P.O. Box 51, Hawaii National Park, Hawaii 96718, USA
- 5Department of Geology, University of Puget Sound, Tacoma, Washington 98416, USA
- 6UNAVCO, 6350 Nautilus Drive, Boulder, Colorado 80301, USA
Abstract
The results of geodetic monitoring since 2002 at Sierra Negra volcano in the Galápagos Islands show that the filling and pressurization of an ∼2-km-deep sill eventually led to an eruption that began on 22 October 2005. Continuous global positioning system (CGPS) monitoring measured >2 m of accelerating inflation leading up to the eruption and contributed to nearly 5 m of total uplift since 1992, the largest precursory inflation ever recorded at a basaltic caldera. This extraordinary uplift was accommodated in part by repeated trapdoor faulting, and coseismic CGPS data provide strong constraints for improved deformation models. These results highlight the feedbacks between inflation, faulting, and eruption at a basaltic volcano, and demonstrate that faulting above an intruding magma body can relieve accumulated strain and effectively postpone eruption.
Footnotes
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↵*Deceased
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↵GSA Data Repository item 2006224, supplementary information on CGPS data processing, displacement vectors, and models used in the study, is available online at http://www.geosociety.org/pubs/ft2006.htm, or on request from editing{at}geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA.
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- Accepted 26 June 2006.
- Received 21 March 2006.
- Revision received 20 June 2006.
- The Geological Society of America, Inc.
