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Preliminary report on engineering and geological effects of the July 2019 Ridgecrest earthquake sequence

July 23, 2019

The Ridgecrest Earthquake sequence included a foreshock event on July 4 2019 (M6.4) and a M7.1 mainshock event on July 5 2019. These events occurred in the Eastern California Shear Zone, near Indian Wells Valley, south of China Lake and west of Searles Valley. GEER has partnered with several organizations to collect perishable data and document the important impacts of these events, including the US Geological Survey, the California Geological Survey, the US Navy, the Southern California Earthquake Center, and local utilities. Critical geotechnical features of this event are extensive left-lateral (M6.4 event) and right-lateral (M7.1 event) surface ruptures over fault segments of variable complexity and width as well as across extensional and compressive step-over zones. We also document lifeline performance at fault crossings (gas, water, electrical), mainshock slip and afterslip, liquefaction and lateral spreading features, and liquefaction effects on structures. These effects are documented using field (ground) mapping and aerial imagery that will support subsequent development of high-resolution digital elevation models. Over 750 ground motions were recorded from the foreshock and mainshock alone, with many additional aftershock records. The data demonstrate significant impacts of site response and rupture directivity on ground motion attributes.

Publication Year 2019
Title Preliminary report on engineering and geological effects of the July 2019 Ridgecrest earthquake sequence
DOI 10.18118/G6H66K
Authors Scott J Brandenberg, Pengfei Wang, Chukwuebuka C Nweke, Kenneth Hudson, Silvia Mazzoni, Yousef Bozorgnia, Kenneth W. Hudnut, Craig A. Davis, Sean K Ahdi, Farzin Zareian, Jawad Fayaz, Richard D Koehler, Colin Chupik, Ian Pierce, Alana Williams, Sinan Akciz, Martin B Hudson, Tadahiro Kishida, Benjamin A. Brooks, Ryan D. Gold, Daniel J. Ponti, Katherine Scharer, Devin McPhillips, Christopher DuRoss, Todd Ericksen, Janis Hernandez, Jay Patton, Brian Olson, Timothy E. Dawson, Jerome Treiman, Kelly Blake, Jeffrey Buchhuber, Chris L M Madugo, Joseph Sun, Andrea Donnellan, Greg Lyzenga, Erik Conway
Publication Type Report
Publication Subtype Other Government Series
Index ID 70204401
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center