TY - JOUR
T1 - Magma-tectonic interactions in Nicaragua
T2 - The 1999 seismic swarm and eruption of Cerro Negro volcano
AU - La Femina, Peter C.
AU - Connor, Charles B.
AU - Hill, Brittain E.
AU - Strauch, Wilfried
AU - Saballos, J. Armando
N1 - Funding Information:
Careful reviews by Dave Hill, Alexander McBirney, Steve Sparks, Tim Dixon, John Stamatakos, Wesley Patrick, and an anonymous reviewer improved the manuscript and are greatly appreciated. Part of this work was performed by the Center for Nuclear Waste Regulatory Analyses (CNWRA) for the U.S. Nuclear Regulatory Commission (NRC) under Contract Nos. NRC-2-97-009 and NRC-02-02-12. The activities reported here were performed on behalf of the NRC Office of Nuclear Material Safety and Safeguards, Division of High Level Waste Repository Safety. This work is an independent product of the CNWRA and does not necessarily reflect the views or regulatory position of the NRC. PCL was also supported by a NASA Florida Space Grant Fellowship and CC was also supported by a grant from the National Science Foundation (EAR-0130602). Several figures were made using The Generic Mapping Tools.
PY - 2004/9/30
Y1 - 2004/9/30
N2 - A low-energy (Volcanic Explosivity Index [VEI] 1), small-volume (0.001 km3 Dense Rock Equivalent [DRE]) eruption of highly crystalline basalt occurred at Cerro Negro volcano, Nicaragua, August 5-7, 1999. This eruption followed three earthquakes (each ∼ Mw 5.2) with strike-slip and oblique-slip focal mechanisms, the first of which occurred approximately 11 h before eruptive activity and within 1 km of Cerro Negro. Surface ruptures formed during these events extend up to 4 km from Cerro Negro, but concentrate ∼ 1 km south of Cerro Negro. Surface ruptures did not occur within 300 m of the cone, however, three new vents formed on the south flank and base of Cerro Negro and on trend with the Cerro La Mula-Cerro Negro volcanic alignment. Earthquake swarms were located northwest and southeast of Cerro Negro and seismicity was elevated for up to 11 days after the initial event. The temporal and spatial patterns of earthquake swarms, surface ruptures, and the eruption location can be explained using the Hill [J. Geophys. Res. 82 (1977) 1347] model for earthquake swarms in volcanic regions, where an eruption is triggered by tectonically induced changes in the regional stress field. In this model, tectonic strain, rather than magmatic overpressure causes dilation of the conduit for magma ascent. Numerical simulations for the 1999 eruption illustrate that the observed velocities (up to 75 m s-1) and fountain heights (50-300 m) can be achieved by eruption of magma with little excess magmatic pressure, in response to changes in Coulomb stress along the Cerro La Mula-Cerro Negro alignment. These observations and models show that 1999 Cerro Negro activity was a tectonically induced small-volume eruption in an arc setting, with the accommodation of extensional strain by dike injection.
AB - A low-energy (Volcanic Explosivity Index [VEI] 1), small-volume (0.001 km3 Dense Rock Equivalent [DRE]) eruption of highly crystalline basalt occurred at Cerro Negro volcano, Nicaragua, August 5-7, 1999. This eruption followed three earthquakes (each ∼ Mw 5.2) with strike-slip and oblique-slip focal mechanisms, the first of which occurred approximately 11 h before eruptive activity and within 1 km of Cerro Negro. Surface ruptures formed during these events extend up to 4 km from Cerro Negro, but concentrate ∼ 1 km south of Cerro Negro. Surface ruptures did not occur within 300 m of the cone, however, three new vents formed on the south flank and base of Cerro Negro and on trend with the Cerro La Mula-Cerro Negro volcanic alignment. Earthquake swarms were located northwest and southeast of Cerro Negro and seismicity was elevated for up to 11 days after the initial event. The temporal and spatial patterns of earthquake swarms, surface ruptures, and the eruption location can be explained using the Hill [J. Geophys. Res. 82 (1977) 1347] model for earthquake swarms in volcanic regions, where an eruption is triggered by tectonically induced changes in the regional stress field. In this model, tectonic strain, rather than magmatic overpressure causes dilation of the conduit for magma ascent. Numerical simulations for the 1999 eruption illustrate that the observed velocities (up to 75 m s-1) and fountain heights (50-300 m) can be achieved by eruption of magma with little excess magmatic pressure, in response to changes in Coulomb stress along the Cerro La Mula-Cerro Negro alignment. These observations and models show that 1999 Cerro Negro activity was a tectonically induced small-volume eruption in an arc setting, with the accommodation of extensional strain by dike injection.
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U2 - 10.1016/j.jvolgeores.2004.05.006
DO - 10.1016/j.jvolgeores.2004.05.006
M3 - Article
AN - SCOPUS:17644389555
SN - 0377-0273
VL - 137
SP - 187
EP - 199
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
IS - 1-3 SPEC. ISS.
ER -