HR: 10:20h
AN: S52B-01    [Abstracts]
TI: Characterizing source properties of events in Southern Africa
AU: * Gok, R
EM: gok1@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave. L-206, Livermore, CA 94618, United States
AU: Walter, W R
EM: bwalter@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave. L-206, Livermore, CA 94618, United States
AU: Linzer, L
EM: LLinzer@csir.co.za
AF: Council of Industrial and Scientific Research, PO 91230, Auckland Park, 2006, South Africa
AU: Julia, J
EM: jjulia@geosc.psu.edu
AF: Pennsylvania State University University, Department of Geosciences, University Park, PA 16802, United States
AU: Nyblade, A A
EM: andy@geosc.psu.edu
AF: Pennsylvania State University University, Department of Geosciences, University Park, PA 16802, United States
AB: Southern Africa has diffuse and relatively low levels of seismicity, except at the southernmost active part of the East African Rift zone in Mozambique, and around active mining areas in South Africa. Many of the mining induced events have depths of less than 4 kilometers, offer the potential for diverse focal mechanisms, and occur at a rate of tens of magnitude 3+ events per year. These characteristics make a good data set to study depth and mechanism effects on local and regional waveforms. We put together a dataset of 165 magnitude 3 and greater events from 1997-2006 from across Southern Africa recorded at the permanent stations BOSA,SUR and LBTB. We calibrated these stations for coda derived source spectra and moment magnitude using the regional envelope methodology of Mayeda et al. (2003). We extend the technique using a revised geometrical spreading path term (Phillips pers. Comm.). We tie the coda Mw to independent values from waveform modeling such as Harvard CMT and Bowers (1997). The resulting spectra are then examined to look at any evidence of systematic behavior with source depth, focal mechanism and any differences between tectonic events and the mining induced events. We are starting to perform regional waveform modeling of some of the larger mining events to provide additional moment values and to determine focal mechanisms. We are also using newly deployed seismic stations of AfricaArray around the mining areas to provide local ground truth information on mine event depth and mechanism.
DE: 7215 Earthquake source observations (1240)
SC: Seismology [S]
MN: 2007 Fall Meeting