HR: 15:00h
AN: S43C-03    [Abstracts]
TI: Relocations of instrumentally recorded earthquakes in the Andean region (1918-present)
AU: * Villasenor, A
EM: antonio@ija.csic.es
AF: Institute of Earth Sciences "Jaume Almera", CSIC, Lluis Sole i Sabaris s/n, Barcelona, 08028, Spain
AU: Engdahl, E R
EM: engdahl@iaspei.org
AF: Department of Physics, University of Colorado, Camps Box 390, Boulder, CO 80903, United States
AB: We have created a comprehensive and self-consistent digital catalog of instrumental seismicity of the Andean region with uniformly computer-determined hypocenters and magnitudes reduced to a common scale. Earthquakes have been relocated by a teleseismic location method that uses recent accurate travel time tables, depth phases, and incorporates corrections for ellipticity, bounce-point bathymetry or topography, and near- station velocity structure. Phase arrival time data for earthquakes after 1963 were obtained in digital form from the International Seismological Centre (ISC). For earthquakes prior to 1964, phase data were obtained by scanning the printed International Seismological Summary (ISS) bulletins and applying optical character recognition. We approached the problem of assigning magnitudes by first combining existing magnitude catalogs into a single multi-valued one. Second we assigned a single magnitude to each event according to a hierarchical scheme and depending on availability. Finally we used these assigned magnitudes to determine the completeness thresholds of the catalog as a function of time. For the early instrumental period (1920's-1963) the catalog is complete down to a magnitude of 6.5, and for the recent period the resulting catalog is complete down to magnitude 5.5. Finally we have analyzed in detail the largest earthquakes in the region and their aftershock sequences, providing estimates of their rupture zones.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Joint Assembly