Geer Team Surface Fault Rupture Observations From the September 2022 Longitudinal Valley Earthquake Sequence, Eastern Taiwan
Description:
We present observations of the September 2022 Longitudinal Valley surface ruptures with a focus on documenting and understanding triggered fault displacement, localized strain partitioning, and variability of repeated surface ruptures on the Chihshang segment of the Longitudinal Valley fault (LVF). The Longitudinal Valley of southeastern Taiwan represents the surface manifestation of a complex plate boundary fault system accommodating oblique sinistral shortening at rates of several centimeters per year between the Philippine Sea Plate and the Eurasian Plate. The 2022 Longitudinal Valley earthquake sequence initiated with an ML 6.4 event on September 17th followed by an Mw 6.9 event on September 18th, with the latter event producing surface rupture along approximately 40 km of the plate boundary consisting of the east-dipping LVF and the west-dipping Central Range fault (CRF). Field observations from the October 2022 GEER reconnaissance indicate that the majority of surface rupture at the latitude of the epicenter occurred on the LVF rather than the adjacent and causative CRF. GEER team surface rupture observations documented oblique shortening on the LVF that was most commonly expressed as either pure shortening or pure translation with on-fault displacements typically ranging from a few tens of centimeters to nearly 1 m. Additionally, surface rupture from the September 2022 sequence was notable for its similarity to the surface rupture distribution during a prior LVF earthquake sequence in 1951. Surface rupture also occurred on the LVF in 2003 and March 23, 2022. Collectively, the 20th and 21st century events on the LVF afford a rare opportunity to understand the variability of surface fault rupture from historic documentation and eyewitness accounts rather than sole reliance on a millennial-scale paleoseismic record.
Session: From Earthquakes to Plate Boundaries: Insights Into Fault Behavior Spanning Seconds to Millennia [Poster]
Type: Poster
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Brian Gray
Student Presenter: No
Invited Presentation:
Authors
Brian Gray Presenting Author Corresponding Author bgray@lettisci.com Lettis Consultants International, Inc. |
Fernando Garcia fegarcia@umich.edu University of Michigan |
Domniki Asimaki domniki@caltech.edu Californa Institute of Technology |
Kuan-Yu Chen kuanyu@narlabs.org.tw National Center for Research in Earthquake Engineering |
Grigorios Lavrentiadis glavrent@caltech.edu California Institute of Technology |
Ben Mason 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 |
Chukwuebuka Nweke chukwueb@usc.edu University of Southern California |
Geer Team Surface Fault Rupture Observations From the September 2022 Longitudinal Valley Earthquake Sequence, Eastern Taiwan
Category
From Earthquakes to Plate Boundaries: Insights Into Fault Behavior Spanning Seconds to Millennia