Tuesday - November 11, 2025

 6:00 p.m. to 8:00 p.m. PST

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""Deep ReMi Surveying to 1 km (3,000 feet) Depths

for Earthquake Hazards, Mining, and Water Resources"

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By: Dr. Jon Louie

Terēan® and Professor Emeritus at the University of Nevada, Reno

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Abstract:​

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​The National Seismic Hazard Map updated periodically by the US Geological Survey has evolved to include input data sets in addition to fault locations and earthquake probabilities, plus Vs30. The need to account for the frequently observed amplification of earthquake shaking by deep sediments more than 30 m thick has led to the testing by earthquake engineers of the factors "Z1.0" and "Z2.5" and their influence on ground motions. Z1.0 and Z2.5 are the depth at which the shear-wave velocity property of rocks first exceeds 1.0 km/s, and 2.5 km/s, respectively. ReMi surveys employing arrays of geophones 0.5 to 20 km long and processed with Terēan ReMi® software are consistently able to directly measure Z1.0 and Z2.5 to depths of 1 km. Terēan Deep ReMi surveys provide a faster and more efficient approach to deep subsurface imaging compared to active-source P-wave and S-wave seismic surveys, passive-seismic surveys using non-linear arrays, HVSR surveys with single stations, or deep electromagnetic surveys. In 2023 the USGS funded comparisons of Deep ReMi, HVSR, and gravity surveying the industrial areas north and east of Reno, Nevada, producing Z1.0 and Z2.5 results and close correlations of thicknesses to well logs. Since 2024, mineral producers such as Anglo Gold Ashanti have been conducting Terēan Deep ReMi surveys to characterize complexly faulted mining prospects to 0.8 km depths, even in quiet rural areas far from any urban microtremor noise. Water-supply agencies such as the Truckee Meadows Water Authority have also been using Terēan surveys to help define aquifer geometry and plan drilling programs.  

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BIO:

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Dr. John N. Louie is a Professor of Geophysics, Professor Emeritus at the University of Nevada, Reno. He has over forty years of university teaching and research experience in geophysics and seismology. He has published with students several well-cited papers on innovations in seismic imaging of earthquake faults and basin structure in California, Nevada, and New Zealand. Over the last 27 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 tens of thousands of sites in California, Nevada, and New Zealand; and on using geological and geotechnical measurements to develop geothermal energy resources, predict earthquake shaking from 3D wave physics, and improve communities' resilience to disasters. In 2023 John co-founded Terēan to bring his developments more rapidly to the benefit of communities everywhere. Terēan® provides ReMi® software, systems, and expertise to hundreds of commercial and agency clients worldwide in the geotechnical, construction, energy, mining, communication, and water resources industries; and for research.

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