SCEC Award Number 12140 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Surface Slip during Large Owens Valley Earthquakes: Compilation and Characterization of Geomorphic Offsets using GeoEarthscope Lidar Data
Investigator(s)
Name Organization
Roland Burgmann University of California, Berkeley
Other Participants Colin Amos, postdoctoral fellow
SCEC Priorities 4c, 2a, 1c SCEC Groups Geology, WGCEP
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
 Advances in our ability to image and analyze active faults using high-resolution lidar provide a unique opportunity to characterize the spatial distribution of slip during large earthquake surface ruptures. For strike-slip faults, along-strike compilation of laterally displaced geomorphic features measured using lidar enables the assessment of surface slip during historical and paleoearthquakes. Here, we test whether surface slip during the 1872 Mw 7.4 – 7.9 Owens Valley earthquake, one of California’s three largest historic ruptures, mimics the displacement during earlier events. We utilize recently developed analysis and processing tools to investigate EarthScope lidar data spanning the ~113-km-long Owens Valley surface rupture. We present 68 new measurements of laterally displaced channels, terrace risers, meander scars, lake shorelines, and fan edges, with offsets up to ~85 m. These data are available for download as a Google Earth .kmz and an ArcGIS shapefile. Where possible, we test the precision of lidar-based measurements by comparing our results to published field estimates of surface slip during this event. Displacements attributed to the most recent event (MRE) range between ~2 and ~8 m, with an average horizontal offset of 5.3 ± 2.0 m, similar to previous field-based estimates. Our along-strike compilation suggests that displacement gradients for the MRE are smooth at the >10 km length scale, in contrast with the distinctly peaked distribution estimated from previous field studies. Progressively larger offsets are attributed to earlier surface ruptures and may imply a similar amount of surface slip to the MRE (~5-6 m). Lateral slip during these events contributes to preliminary peaks in the cumulative offset frequency density at ~12 and ~17 m. The precision of these peaks likely reflects some bias toward well-preserved offsets, since the majority of offset features reflect displacement during the most recent event. As we expand our database of offset measurements and further develop a long-term paleoseismic history, we will test whether or not similar patterns of surface slip are repeated as characteristic earthquakes during surface ruptures on the Owens Valley fault.
Intellectual Merit Quantifying the seismic hazard imposed by an individual fault requires accurate knowledge of the spatial distribution of slip and the timing of past, surface-rupturing earthquakes. The 1872 Mw 7.4 – 7.9 Owens Valley earthquake ranks among the largest historical earthquake ruptures in California and produced comparable displacement and shaking intensities to the 1906 and 1857 San Andreas earthquakes. Although field studies document the average amount of surface slip, we lacked a comprehensive understanding of how slip during the 1872 earthquake was spatially distributed and have known comparatively little about the cumulative slip caused by earlier events. Recent availability of high-resolution lidar topography spanning the 1872 Owens Valley surface rupture in southeastern California enables reevaluation of the amount and extent of surface slip during the 1872 Owens Valley and earlier events. By compiling and cataloging surface slip measurements based on patterns of displaced Quaternary landforms, we produce a new database of fault offsets designed to improve our understanding of slip-per-event during Owens Valley earthquakes. This study sheds light on whether previous ruptures produced similar displacements to the 1872 earthquake and allow better characterization of the estimated moment release associated with Owens Valley surface ruptures.
Broader Impacts This project forms the basis of a MSc project (Haddon) currently underway at Western Washington University and was presented at the 2012 SCEC and AGU annual meetings (Haddon et al., 2012a, 2012b).
Exemplary Figure Figure 2. (A) Compilation of new and published measurements of dextrally offset landforms along the Owens Valley fault. Plot excludes measurements currently pending field assessment. Symbols for features identified using GeoEarthscope lidar (purple boxes) are scaled by quality ranking, from high to low. Published data (red points) are from Bateman (1961), Lubetkin and Clark (1987), Beanland and Clark (1994), Lee et al., (2001), Slemmons et al., (2008), and Kirby et al. (2008). Grey inset boxes highlight right-lateral offsets measured at sites within broad (1-3 km) zones of deformation. Measurements within these zones do not span the apparent width of deformation and may be regarded as minimum values. (B) Plot of cumulative offset frequency density for lateral offset measurements compiled on Figure 3a. The summary curve is peaked at values that may correspond to the most recent event (~6 m) and earlier surface ruptures (~12 and ~17 m). Small offsets (<3.5 m) are measured within zones of distributed deformation and contribute to a preliminary peak at ~2.5.
Beth Haddon, Colin Amos and Roland Burgmann, unpublished
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