HR: 0800h
AN: S11A-0277    [Abstracts]
TI: Velocity Structure Near the Site of the Northern 2002 Embayment Seismic Excitation Experiment Explosion From Reflection, Refraction, and Strong Motion Measurements
AU: * Rieger, D
EM: dmr6645@sru.edu
AF: CERI, University of Memphis, 3876 Central Ave., Ste. 1, Memphis, TN 38152-3050, United States
AU: Langston, C A
EM: clangstn@memphis.edu
AF: CERI, University of Memphis, 3876 Central Ave., Ste. 1, Memphis, TN 38152-3050, United States
AU: Williams, R A
EM: rawilliams@usgs.gov
AF: U.S. Geological Survey, P.O. Box 25046 Mail Stop 966, Denver, CO 80225-0046, United States
AU: Worley, D M
EM: worley@usgs.gov
AF: U.S. Geological Survey, P.O. Box 25046 Mail Stop 966, Denver, CO 80225-0046, United States
AB: P wave reflection and refraction data and SH wave refraction data were taken in November 2006 near the site of the northern 5000 lb explosion of the 2002 Embayment Seismic Excitation Experiment to provide independent constraints on detailed velocity structure between the explosion source and an array of strong motion seismographs that recorded the explosion. Reflection images display prominent reflectors throughout the 650m thick section of unconsolidated Mississippi embayment sediments in addition to the major Paleozoic/Upper Cretaceous unconformity at the base. Reflection statics can be constrained by the unusual and fortuitous recording of relatively deep microearthquakes on the P wave reflection spread and show that static effects in the P wave data are very small. P and S wave velocity models for the sediments are constructed using refraction travel times, Love and Rayleigh wave dispersion measurements, and vertical velocity variations inferred from the P wave reflection images. These models are used to check and refine a velocity model inferred from well-log data elsewhere in the embayment and from modeling waveform data from the nearby strong motion array. Synthetic models for the strong motion waveforms are robust and clearly define the major body and surface wave propagation effects due to the unconsolidated sediments. These results reinforce the conclusion that the unconsolidated sediments of the embayment will form a significant waveguide for high-frequency seismic waves induced by near-surface faulting.
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting