Presentation
Surface Slip During Large Owens Valley Fault Earthquakes
AGU Fall Meeting
(2012)
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 seek to 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 ~140-km-long Owens Valley surface rupture. We present over 70 new measurements of laterally displaced channels, terrace risers, meander scars, lake shorelines, and fan edges, with offsets up to 25 m. 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 9 m, with an average horizontal offset of ~5 ± 2 m. 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 (~5-7 m). Lateral slip during these events contributes to preliminary peaks in the cumulative offset frequency density at ~12 and ~18 m. The precision of these peaks likely reflects some bias toward well-preserved offsets, since the majority of offset features reflect displacement during the 1872 event. Taken together, our results indicate some variability in the amount of surface slip during Owens Valley surface ruptures, although large earthquakes appear to repeatedly rupture a similar fault extent. 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.
Keywords
- Earthquake surface ruptures,
- Strike-slip faults,
- Owens Valley fault
Disciplines
Publication Date
December, 2012
Location
San Francisco, CA
Citation Information
Haddon, E.K.*, C.B. Amos, and R. Burgmann (2012) Surface slip during large Owens Valley fault earthquakes, Eos Trans. AGU, Fall Meet. Suppl., Abstract T31B-2342