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Published April 2015 | Published
Journal Article Open

Fault‐Slip Distribution of the 1999 M_w 7.1 Hector Mine Earthquake, California, Estimated from Postearthquake Airborne LiDAR Data

Abstract

The 16 October 1999 Hector Mine earthquake (M_w 7.1) was the first large earthquake for which postearthquake airborne Light Detection and Ranging (LiDAR) data were collected to image the fault surface rupture. In this work, we present measurements of both vertical and horizontal slip along the entire surface rupture of this earthquake based on airborne LiDAR data acquired in April 2000. We examine the details of the along‐fault slip distribution of this earthquake based on 255 horizontal and 85 vertical displacements using a 0.5 m digital elevation model derived from the LiDAR imagery. The slip measurements based on the LiDAR dataset are highest in the epicentral region, and taper in both directions, consistent with earlier findings by other works. The maximum dextral displacement measured from LiDAR imagery is 6.60±1.10  m, located about 700 m south of the highest field measurement (5.25±0.85  m). Our results also illustrate the difficulty in resolving displacements smaller than 1 m using LiDAR imagery alone. We analyze slip variation to see if it is affected by rock type and whether variations are statistically significant. This study demonstrates that a postearthquake airborne LiDAR survey can produce an along‐fault horizontal and vertical offset distribution plot of a quality comparable to a reconnaissance field survey. Although LiDAR data can provide a higher sampling density and enable rapid data analysis for documenting slip distributions, we find that, relative to field methods, it has a limited ability to resolve slip that is distributed over several fault strands across a zone. We recommend a combined approach that merges field observation with LiDAR analysis, so that the best attributes of both quantitative topographic and geological insight are utilized in concert to make best estimates of offsets and their uncertainties.

Additional Information

© 2015 Seismological Society of America. Manuscript received 2 May 2013; Published Online 3 February 2015. This research was supported by Public Service Funds for earthquake studies (201308012) and Fundamental Research Funds in the Institute of Geology (IGCEA1125). Tao Chen was sponsored as a visiting scholar to the U.S. Geological Survey (USGS) by the China Scholarship Council (Grant Number 2010419008). Work by D. Z. Zhang was supported, in part, by the Multi-Hazards Demonstration Project of the USGS. Jing Liu-Zeng and Kate Scharer helped us to improve the manuscript. We thank Katherine Kendrick for providing the database of field measurements from the original postearthquake observations of Treiman et al. (2002). We also thank an anonymous reviewer and Mike Oskin for their advice. Original LiDAR data acquisition was funded by the USGS and the Southern California Earthquake Center (SCEC). SCEC is funded by National Science Foundation Cooperative Agreement EAR-1033462 and USGS Cooperative AgreementG12AC20038. The SCEC contribution number for this article is 1973.

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August 20, 2023
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October 23, 2023