SCEC Award Number 15189 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title The 1992 Landers rupture re-examined using topography generated from legacy air-photos
Investigator(s)
Name Organization
Edwin Nissen Colorado School of Mines Katherine Scharer United States Geological Survey Kenneth Hudnut United States Geological Survey
Other Participants Kendra Johnson (graduate student, Colorado School of Mines)
SCEC Priorities 4b, 1a, 4c SCEC Groups Geodesy, Geology, FARM
Report Due Date 03/15/2016 Date Report Submitted 11/09/2016
Project Abstract
 The Mw 7.2 Landers earthquake of 28 June 1992 is one of the earliest earthquakes with a well-documented shallow slip deficit. This project investigates its causes using new rupture zone topography datasets constructed from archived aerial photographs taken beforeand just subsequent to the earthquake. By revealing subtle off-fault deformation, the new digital terrain models (DTMs) and orthophotos will allow us to assess the influence of near-surface lithology and surface trace complexity on fault damage zone width. These observations will help address whether the shallow slip deficit depends on the surface lithology or cover thickness through which the rupture propagated, or whether it is invariant to these factors and instead reflects the structural immaturity of the causative faulting. Our results will have implications for the mechanical properties of discontinuous, low cumulative-slip faults in southern California and elsewhere.
Intellectual Merit The Mw 7.3 Landers earthquake is one of the earliest earthquakes with a well-documented "shallow slip deficit". We propose to investigate its causes using a new rupture zone topography dataset constructed from archived USGS airplane photographs. A roughly decimeter resolution Digital Terrain Model (DTM) and co-registered orthophoto will be generated using Structure-from-Motion algorithms that simultaneously reconstruct the camera positions and orientations, a significant advance on traditional stereo-photogrammetry which makes this project feasible. By revealing subtle off-fault deformation, the new DTM and orthophoto will allow us to assess the influence of near-surface lithology and surface-trace complexity on fault damage zone width. These observations will help address whether the shallow slip deficit depends on the surface lithology or cover thickness through which the rupture propagated, or whether it is invariant to these factors and instead reflects the structural immaturity of the causative faulting. Note that these data will augment (rather than duplicate) ongoing efforts by James Dolan and colleagues to map coseismic slip at shallow depths using optical image correlation techniques, whose wider (10s of meters) aperture is unlikely to provide measurements within the damage zone or precisely constrain its overall width. Overall, our results will have implications for the mechanical properties of discontinuous, low cumulative-slip faults in southern California and elsewhere.
Broader Impacts None submitted by investigator.
Exemplary Figure Figure 7 from the report.