SCEC Award Number 14160 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Combined Hyperspectral and Field Mapping of the Lavic Lake fault
Investigator(s)
Name Organization
Joann Stock California Institute of Technology
Other Participants Janet Harvey, Ken Hudnut, David Tratt, David Lynch
SCEC Priorities 4b, 4c, 4a SCEC Groups Geology, SoSAFE, Geodesy
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
 We conducted new field and computer based investigation of the surface rupture of the October 16, 1999 Hector Mine Earthquake, under SCEC proposal numbers 12188, 13151, and 14160 (2012 - 2014). Our field work focused on the ~8 km long maximum slip zone of the rupture, roughly corresponding to >4 m dextral offset. Field work included 1) walking the fault, making detailed measurements of offsets, and photo documenting the current state of the rupture; 2) mapping the fault traces with a Trimble GeoXH high precision handheld GPS unit (±10 cm); 3) carrying out field checks of 87 computer-based offset measurements from the 2000 LiDAR dataset; 4) high-resolution low-altitude (<100 m AGL) photography of the maximum slip zone during a helicopter overflight; and 5) surveys of selected high importance offset features using Terrestrial Laser Scanner. Office-based work included 1) creating a difference raster for the entire 8 km maximum slip zone from exactly congruent DEM’s made from years 2000 and 2012 LiDAR data sets; 2) measurement of 31 offsets from the 2012 LiDAR data set to compare with the other measurements in the maximum slip zone, and 3) analysis of thermal infrared remote sensing data. Newest results include a database of 50 offset measurements (georeferenced and photo documented) made by our team on the ground, and examples of field checks that both strongly agree and disagree with computer based LiDAR offset measurements.
Intellectual Merit SCEC funded us for comparative analysis of the two LiDAR data sets and field work along the rupture of the Mw 7.1 Hector Mine earthquake. The LiDAR data set collected along the rupture in the year 2000 (Hudnut et al, 2002; Zhang et al., 2010; Chen et al., 2015) had three main contributions to a better understanding of this rupture: (1) it increased the spatial density of horizontal displacements, (2) it suggested a new location and larger magnitude of the maximum lateral slip, and (3) it documented rapid slip variations along geometrically simple sections of the fault. In May 2012 a new LiDAR dataset was collected by NCALM under a data-only seed grant to Caltech graduate student Francis Sousa. This covered a significantly broader swath along the same length of the fault. Together these two LiDAR datasets (Fig. 1) comprise a complete, high resolution documentation of this major earthquake surface rupture and show the geomorphic evolution of the rupture in a period of 12 years. Along with two data sets of field measurements (one from 1999 after the earthquake, and one done under this project) we have a clear comparison of what factors changed since 1999/2000, and what considerations need to be emphasized in measuring strike-slip fault offsets from LiDAR data alone.
Broader Impacts Graduate student Frank Sousa was trained in LiDAR data processing and production and differencing of DEMS. Sousa and Witkosky also were trained in presenting research results at conferences (Sousa et al., 2012a and 2012b, 2013a, 2013b, 2014a, 2014b; Witkosky et al., 2014a, 2014b), and in helping to write proposals. All three graduate students (Sousa, Harvey and Witkosky) were trained in field observations of active faults. Witkosky and Sousa were trained in collection of TLS data. The 2012 LiDAR data set produced by this study is available on the OpenTopography web site. The aerial photos shot over the fault zone will be made available on a public web site of the USGS after approval from the US Marine Corps public relations office at 29 Palms US Marine Corps Air-Ground Combat Center.
Exemplary Figure Figure 4. Comparison of field measurement of offset and LiDAR-derived measurements of offset, from each of the data sets, for the Armory site. Views look to the SW. Note difference in resolution between 2000 and 2012 LiDAR based DEMs. Same location as Figure 3. Figure made by Frank Sousa.