HR: 0800h
AN: T21A-0350    [Abstracts]
TI: Spatial and Temporal Patterns of Non-Volcanic Tremor Source Locations Along the Oaxacan Segment of the Middle America Subduction Zone
AU: * Hinojosa-Prieto, H R
EM: hinojohr@muohio.edu
AF: Miami University, Department of Geology 114 Shideler Hall, Oxford, OH 45056, United States
AU: Brudzinski, M R
EM: brudzimr@muohio.edu
AF: Miami University, Department of Geology 114 Shideler Hall, Oxford, OH 45056, United States
AU: Cabral-Cano, E
EM: ecabral@igeofcu.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, DF 04510, Mexico
AU: Arciniega-Ceballos, A
EM: maac@igeofcu.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, DF 04510, Mexico
AU: Diaz-Molina, O
EM: oscard@igeofcu.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, DF 04510, Mexico
AU: DeMets, C
EM: chuck@geology.wisc.edu
AF: University of Winsconsin-Madison, Department of Geology and Geophysics, Madison, WI 53706, United States
AB: Convergent tectonic plate boundaries generate large devastating earthquakes when plate motion accumulates tectonic stresses on the locked, seismogenic zone of the subduction zone interface. Downdip from the seismogenic zone, where increasing temperatures, pressure and slab dehydration limit frictional behavior, periodic slow slip events appear to occur in a transitional zone. The slow slip events have been shown to correlate with non-volcanic tremor (NVT), forming so-called episodic tremor and slip (ETS). The Oaxacan segment of the Middle America subduction zone is an ideal area for detailed ETS studies due to its relatively rapid convergent rates, shallow subduction angle, short megathrust earthquake recurrence intervals (decades), and short trench-to-coast distances that bring the seismogenic and transition zones of the plate interface as much as 250 km inland from the coastline. Previously analyzed slow slip events in southern Mexico occur over vast, deep areas of the subduction zone interface, and may even extend updip into the seismogenic zone, potentially playing a role in the timing of location of upcoming megathrust earthquakes. In addition to recent expansion of the permanent GPS station network, a new seismic deployment consists of 8 broadband (high-resolution) seismometers geographically dispersed inland along the Oaxacan segment, providing the means to examine NVT signals in detail for the first time in this region. Our analysis of NVT follows the approach of Obara (2002), using cross-correlation of filtered envelope seismograms to define S arrivals that are then converted to hypocentral locations. We apply this technique to data recorded over the first year of the deployment to determine spatial and temporal patterns in source locations. Specifically, we will address where and when NVT events start and stop, as well as migration rates, directions and geographic variability. A key issue we will investigate is why NVT signals appear more frequently (~2 month recurrence) than slow slip (12-24 month recurrence).
DE: 7215 Earthquake source observations (1240)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8123 Dynamics: seismotectonics
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
DE: 9350 North America
SC: Tectonophysics [T]
MN: 2007 Fall Meeting