Association of Environmental and Engineering Geologists Meeting Announcement

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Association of Environmental and Engineering Geologists
Great Basin Section (AEG)
Meeting Announcement
Thursday, February 18, 2016

SPEAKER: Dr. John N. Louie

Topic: Deep ReMi Imaging – Mapping Shear-Wave Velocities to 1 km Depth and Greater in Reno/Tahoe Using Refraction Microtremor
Satish Pullammanappallil (Optim, Reno, NV 89501; satish@optimsoftware.com)
Aasha Pancha (Victoria University of Wellington, New Zealand; Aasha.Pancha@vuw.ac.nz)
John Louie (Nevada Seismological Laboratory, UNR, NV 89557; louie@seismo.unr.edu)

LOCATION:
RAPSCALLION SEAFOOD HOUSE & BAR
1555 S. WELLS AVENUE, RENO, NEVADA 89502
SOCIAL HOUR: 5:30 PM, DINNER: 6:30 PM
PRESENTATION: 7:00 PM

RSVP NO LATER THAN 5PM, TUESDAY FEBRUARY 16 BY 5:00
@ 775¬221¬1369 or justin.mcdougal@amecfw.com

Cost: Members: $25.00, non-members: $29.00

Abstract: The Refraction Microtremor (ReMi) technique, which came into use during 2002, has now become a standard tool for assessing shear-wave velocities for engineering applications. It is used for site-class studies as well as assessing ground conditions, including 1D and 2D velocity-depth profiling to shallow depths of approximately 100 m. Over the last few years, we have successfully extended the application of the method to depths greater than 1 km. The use of deep ReMi, which relies primarily on ambient noise, for estimation of shear-wave velocities to kilometer depths, allows for mapping the thickness and velocity of deep basins. The deep shear-wave velocity results in turn can be used for accurate modeling and calibration of recorded earthquake ground motions in the target urban areas. Such models have the potential to be an essential part of seismic hazard evaluation. We present results from several deep ReMi studies conducted in Reno-Tahoe basins. In all cases data were acquired using wireless instruments coupled with low-frequency geophones deployed in 3 km long arrays across the densely populated urban environment. In addition to mapping basement as deep as 900 m, the lateral velocity variations reveal deep-seated fault structure. Characterization of previously unknown faults is vital as well towards quantifying earthquake ground motion and seismic potential. Modeling was constrained using gravity data and earthquake tomography models when available.

Bio: Dr. John N. Louie, Professor at the Nevada Seismological Laboratory, has over twenty-five years of university teaching and research experience in geophysics. He has published with students several well-cited papers on innovations in seismic imaging of earthquake faults in California, Nevada, and New Zealand. Over the last 15 years, Dr. Louie has developed a faster and more efficient site-assessment survey technique for earthquake-hazard evaluation, Refraction Microtremor. Research on this technology continues, measuring thousands of sites in California, Nevada, and New Zealand; and on using geological and geotechnical measurements to predict earthquake shaking from 3D wave physics, and improve communities’ resilience to disasters.

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