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Report | SCEC Research Accomplishments
El Mayor-Cucapah Earthquake
Investigations are maturing in response to the 4 April 2010 El Mayor-Cucapah earthquake in northernmost Baja California.
This is the first earthquake where comprehensive lidar topographic surveys and differential lidar have been available to map
the rupture and constrain near-field deformation (Figure 12). Lidar data collection was supported by an NSF-RAPID grant,
supplemented by SCEC funds that allowed for expansion of the survey. Oskin et al. (in review) describe the collection and
Figure 12. A. Elevation difference map (post-pre) generated from lidar surveys obtained before and after the 2010 El Mayor-Cucapah
earthquake. Cross-section shows folding between two dextral oblique normal faults that slipped in this earthquake. B. Elastic model of the
Paso Inferior Accommodation Zone, based on observed fault offsets. Note how the model reproduces observations well along the crosssection
in A (model shown as red dashed line).
first results of this survey, highlights of which include large near-field strains (~10-3) that appear to be elastically generated,
and evidence for a blind strike-slip fault system that slipped beneath the Colorado River delta. Overall, the El Mayor Cucapah
earthquake represents the latest of a class of distributed, multi-fault earthquake ruptures that present difficult-to-quantify,
distributed seismic hazard. Rupture mapping led by a joint USA-Mexico team of Fletcher and Rockwell, has revealed up to
seven fault segments that slipped in this earthquake. A paper summarizing the numerous measurements and lidar-assisted
rupture mapping will soon be submitted for publication. Efforts are ongoing to compare this rupture to previous events,
including the immediately adjacent rupture generated by the 1892 Laguna Salada earthquake. That two earthquakes of similar
size occurred within a few kilometers of each other challenges the role that elastic rebound may play in reducing earthquake
hazard immediately after a nearby event. The latest and ongoing research from the El Mayor-Cucapah earthquake, including
results from analysis of both airborne and terrestrial lidar, will be presented at a workshop at the upcoming 2011 SCEC annual
meeting. Current registration for this workshop already exceeds 100 persons.
Shallow Slip Deficits
50 | Southern California Earthquake Center