Geotechnical Field Observations From the 18 September 2022 Mw6.9 Chihshang, Taiwan Earthquake
Description:
We performed post-earthquake reconnaissance in Taiwan following the 18 September 2022 MW6.9 Chihshang, Taiwan earthquake. The National Science Foundation-funded Geoengineering Extreme Events Reconnaissance (GEER) Association sponsored our work. The earthquake occurred on the Central Range strike-slip fault, with the rupture direction extending north from the epicenter. Near-field seismic stations measured PGAs exceeding 0.5 g along the fault. PGVs increased in the direction of the rupture with average intensities of 8 cm/sec near the epicenter, increasing along the fault to 89 cm/sec at the northern terminus. The ground motion recordings of the east (approximately fault normal) component show strong velocity pulses in the direction of the rupture. Our team investigated earthquake-induced landslides, surface fault rupture, and bridge damage using traditional reconnaissance techniques as well as unmanned aerial vehicles (UAVs) equipped with cameras and lidar. Despite the earthquake ground motion being relatively strong given the small source-to-site distances to important locations throughout the alluvial plain from Chihshang to Ruisui, we did not observe any surface manifestations of liquefaction. We speculate that liquefaction did not occur due to a combination of short earthquake durations as well as a variation of soil types throughout the alluvial plain. The observations are important for geotechnical engineers practicing in seismically active areas with nearby, active faults capable of creating strong velocity pulses. In particular, we have an opportunity to further our understanding of liquefaction (or non-liquefaction) during short, pulse-like earthquake motions.
Session: Advances in Probabilistic Seismic Hazard Analysis and Applications [Poster]
Type: Poster
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Ben Mason
Student Presenter: No
Invited Presentation:
Authors
Domniki Asimaki domniki@caltech.edu California Institute of Technology |
Ben Mason Presenting Author Corresponding Author ben.mason@oregonstate.edu Oregon State University |
Adda Athanasopoulos-Zekkos adda.zekkos@berkeley.edu University of California, Berkeley |
Trevor Carey trevor.carey@civil.ubc.ca University of British Columbia |
Fernando Garcia fegarcia@umich.edu University of Michigan |
Brian Gray bgray@lettisci.com Lettis Consultants International Inc. |
Grigorios Lavrentiadis glavrent@caltech.edu California Institute of Technology |
Chukwuebuka Nweke chukwueb@usc.edu University of Southern California |
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Geotechnical Field Observations From the 18 September 2022 Mw6.9 Chihshang, Taiwan Earthquake
Category
General Session