HR: 08:30h
AN: T11F-03    [Abstracts]
TI: Non-Volcanic Tremor Observed in Guerrero, Mexico
AU: Payero, J
EM: payero@ollin.igeofcu.unam.mx
AF: Postgrado en Ciencias de la Tierra, IGF, UNAM, Av. Universidad, 3000, Copilco, Coyoacan, Mexico, DF 04510, Mexico
AU: Payero, J
EM: payero@ollin.igeofcu.unam.mx
AF: Instituto Sismologico UASD, Juan Sánchez Ramírez esq Alma Mater, Santo Domingo, DN 1355, Dominican Republic
AU: * Kostoglodov, V
EM: vladi@servidor.unam.mx
AF: Instituto de Geofisica UNAM, Av. Universidad, 3000, Copilco, Coyoacan, Mexico, DF 04510, Mexico
AU: Shapiro, N
EM: nshapiro@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris and CNRS, Place Jussieu - Case 89, Paris, 75252, France
AU: Mikumo, T
EM: mikumo@maia.eonet.ne.jp
AF: Instituto de Geofisica UNAM, Av. Universidad, 3000, Copilco, Coyoacan, Mexico, DF 04510, Mexico
AU: Iglesias, A
EM: amg@ollin.igeofcu.unam.mx
AF: Instituto de Geofisica UNAM, Av. Universidad, 3000, Copilco, Coyoacan, Mexico, DF 04510, Mexico
AU: Perez, X
EM: xyolipc@gmail.com
AF: Instituto de Geofisica UNAM, Av. Universidad, 3000, Copilco, Coyoacan, Mexico, DF 04510, Mexico
AU: Clayton, R
EM: clay@gps.caltech.edu
AF: CALTECH, GPS, MC 170-25, 1200 E. California Blvd., Pasadena, CA 91125, United States
AB: Non-volcanic tremor (NVT) activity is clearly identified as episodes of higher spectral amplitude in the range of 1-8 Hz in daily spectrograms from the continuous records at broad band seismic stations in the Guerrero state, Mexico. The analyzed data cover a period of 2001-2007 when in 2001-2002 a large slow slip event (SSE) had occurred in the Guerrero-Oaxaca region, and then followed by a steady-state interseismic epoch of 2003-2005 and a new large SSE occurred in 2006. The tremor signals in Mexico are very similar to those obtained in Cascadia subduction zone. An average tremor burst remains for 10-60 min and is dominated by S-waves. More than 100 strong NVT bursts were recorded by the most of the Meso-American Subduction Experiment (MASE 2005-2007) seismic stations with the majority of epicenters clustered in the narrow band of ~40 x 150 km² to the south of Iguala city and in parallel to the coastline. Depths of NVT hypocenters are poorly constrained but mostly scattered in the continental crust between 5 and 45 km depth. Tremor activity is significantly higher during the 2001-2002 and 2006 SSE compared with that for the "quiet" period of 2003-2005. Very low NVT occurrence for the period of about 2 months right after the SSE is apparent in 2002 and 2006. Similar to the Japan and Cascadia subduction zones, the main tremor activity in Mexico develops in the area close to the mantle wedge. In Mexico it is located at approximately 200 km inland from the trench. While conductivity pattern obtained from the magnetotelluric profile in Guerrero does not correlate directly with the NVT distribution, gravity and magnetic anomalies modeling favors a hypothesis that the NVT is apparently related to the dehydration and serpentinization processes.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting