[ghsc-seminars] THIS MORNING, Tuesday, Aug 20th @ 10 am - Martin Chapman, Virginia Tech

[Boyd, Oliver]

*Amplification and Attenuation in the Gulf and Atlantic Coastal Plain and
the Latest Results of Monitoring the Central Virginia Seismic Zone*

*Martin Chapman*
*Department of Geosciences*
*Virginia Tech *

     We investigated the difference in response of sites within and outside
Coastal Plain and found that Coastal Plain sites experience greater
amplification of low-frequency ground motions and attenuation at
high-frequencies. We found that differential kappa values determined from
the coda are correlated with the thickness of the sediment section.
Analysis of residuals between observed and predicted ground motions
suggests that incorporating the amplification and attenuation as functions
of sediment thickness may improve ground motion prediction models for the
Coastal Plain region.
     I also report on a twenty-five station temporary seismic network
operated in central Virginia from April 2017 through November 2018. A total
of 457 earthquakes were located, 400 of which are aftershocks of the Mw 5.7
August 23, 2011 Mineral earthquake with a general pattern of hypocenters
that is not appreciably different from that of the immediate (August 25 –
December 31, 2011) aftershocks. The results establish that the aftershock
spatial distribution is temporally stationary, and that the stress field
responsible for the early aftershocks at shallow depths is also temporally
persistent.

*Tuesday, August 20th**, 2019*
*10-11am*
*  (Mountain Time)*
*USGS, 1711 Illinois Street, Golden, CO*
*Entry Level Seminar Room (204)*

*Note: Please arrive *~5 minutes early* and *bring photo ID* for
airport-style security measures now in place at the USGS building.

Thank you,
GHSC Seminar Committee

Ben
Mirus - bbmirus at usgs.gov
Josh Rigler - erigler at usgs.gov
Oliver Boyd - olboyd at usgs.gov <oboyd at usgs.gov>
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