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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L04309, doi:10.1029/2004GL021788, 2005

Evidence for static stress changes triggering the 1999 eruption of Cerro Negro Volcano, Nicaragua and regional aftershock sequences

M. Díez

Department of Geology, University of South Florida, Tampa, Florida, USA


P. C. La Femina

Rosentiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida, USA


C. B. Connor

Department of Geology, University of South Florida, Tampa, Florida, USA


W. Strauch

Instituto Nicaraguense de Estudios Territoriales (INETER), Managua, Nicaragua


V. Tenorio

Instituto Nicaraguense de Estudios Territoriales (INETER), Managua, Nicaragua


Abstract

Remarkable evidence of coupling between tectonic and magmatic events emerges from investigation of three tectonic earthquakes, aftershock sequences and eruption of Cerro Negro volcano, Nicaragua in 1999. Here, we explain this coupling through static stress changes following three Mw 5.2 earthquakes. We use focal mechanism solutions to estimate fault system geometry and magnitude of slip from these events, which are then used to calculate the change in minimum horizontal principal stress (σ3) for the region and the change in Coulomb failure stress on optimally oriented fault planes. Results of these simulations indicate that σ3 was reduced by ∼0.08 MPa and that Coulomb failure stress was raised by 0.001 to 0.2 MPa in the region. A Kolmogorov-Smirnov test demonstrates spatial correlation of Coulomb failure stress changes and triggered seismicity and volcanism, and suggests that these small changes in static stress can trigger subsequent geophysical events under appropriate circumstances.

Received 19 October 2004; accepted 11 January 2005; published 23 February 2005.

Index Terms: 7230 Seismology: Seismicity and tectonics (1207, 1217, 1240, 1242); 7280 Seismology: Volcano seismology (8419); 8164 Tectonophysics: Stresses: crust and lithosphere; 8414 Volcanology: Eruption mechanisms and flow emplacement.

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Citation: Díez, M., P. C. La Femina, C. B. Connor, W. Strauch, and V. Tenorio (2005), Evidence for static stress changes triggering the 1999 eruption of Cerro Negro Volcano, Nicaragua and regional aftershock sequences, Geophys. Res. Lett., 32, L04309, doi:10.1029/2004GL021788.