HR: 14:55h
AN: S52H-06 [PDF]
TI: Regional Wave Propagation in Southeastern United States
AU: * Jemberie, A L
EM: ajemberi@memphis.edu
AF: CERI,
The University of Memphis, 3876 Central Avenue, Memphis, TN 38152 United States
AU: Langston, C A
EM: clangstn@memphis.edu
AF: CERI,
The University of Memphis, 3876 Central Avenue, Memphis, TN 38152 United States
AB:
Broad band seismograms from the April 29, 2003, M4.6 Fort Payne, Alabama earthquake are analyzed to infer mechanisms of
crustal wave propagation, crust and upper mantle velocity structure in southeastern United States, and source parameters of
the event. In particular, we are interested in producing deterministic models of the distance attenuation of earthquake
ground motions through computation of synthetic seismograms. The method first requires constraining the source parameters of
an earthquake and then modeling the amplitude and times of broadband arrivals within the waveforms to infer appropriate
layered earth models. A first look at seismograms recorded by stations outside the Mississippi Embayment (ME) show clear body
phases such P, sP, Pnl, Sn and Lg. The ME signals are qualitatively different from others because they have longer durations
and large surface waves. A straightforward interpretation of P wave arrival times shows a typical upper mantle velocity of
8.18 km/s. However, there is evidence of significantly higher P phase velocities at epicentral distances between 400 and
600km, that may be caused by a high velocity upper mantle anomaly; triplication of P-waves is seen in these seismograms. The
arrival time differences between regional P and the depth phase sP at different stations are used to constrain the depth of
the earthquake. The source depth lies between 9.5 km and 13km which is somewhat more shallow than the network location that
was constrained to 15km depth. The Fort Payne earthquake is the largest earthquake to have occurred within the Eastern
Tennessee Seismic Zone.
DE: 7203 Body wave propagation
DE: 7215 Earthquake parameters
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting