SCEC Award Number 11022 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Resolving Fine-Scale Fault Structures in Southern California using Improved Focal Mechanisms and Relocated Seismicity from Waveform Cross-correlation
Investigator(s)
Name Organization
Peter Shearer University of California, San Diego Egill Hauksson California Institute of Technology
Other Participants Xiaowei Chen (graduate student)
SCEC Priorities A4, A10, C SCEC Groups USR, Seismology, EFP
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 In 2011, we released the latest version of our relocated catalog (the HYS catalog) containing high-precision locations of over 500,000 events from 1981 to June 2011. Our previous catalogs, such as the LHS catalog by Lin et al. (2007b) have been used by a number of other researchers, leading to new results that would not have been possible with standard catalogs. The complex spatial distribution of the events reflects the different processes that contribute to the generation of both background and triggered seismicity. The Pacific North-America plate tectonic deformation is the main process that causes major earthquakes and their aftershock sequences.
Intellectual Merit In 2011, we released the EYS relocated catalog containing high-precision locations of over 500,000 events from 1981 to 2011/06. The EYS and our previous catalogs (LSH) have been used by a number of other researchers, leading to new results that would not have been possible with standard catalogs. For example, Felzer and Brodsky (2006) argued that aftershock behavior from M 2–6 mainshocks favors a dynamic triggering model, Vidale and Shearer (2006) identified many distinctive characteristics of earthquake swarms in southern California, Davidsen et al. (2006) found new statistical features of seismicity with unexpected scaling properties, Shearer and Lin (2009) identified Mogi-doughnut behavior in seismicity preceding small earthquakes, and Tape et al. (2009) used the LSH locations in the starting model for their recent adjoint tomography study of the southern California crust.
Broader Impacts This project helped support female graduate student Xiaowei Chen as well as a PostDoc.
The ever-expanding SCSN archive of waveforms from more than 500,000 local earthquakes provides an invaluable resource for seismology research that has only begun to be exploited. However, efficient mining of these data requires the development of new analysis methods, an effort that goes beyond the limited resources of individual scientists. We have coordinated our efforts and developed common tools and data products that can be used by us and other researchers to accomplish many SCEC goals.
Exemplary Figure Figure 1. Event locations from the HYS catalog (1981 – 2011/06). Similar-event clusters that have been relocated by using waveform cross-correlation are shown in black. Events in the SCSN catalog (and uncorrelated events in the other catalogs) are shown in green. Events with M ≥ 5.5 are shown as stars. Faults are from Jennings (1995) with late Quaternary faults in shades of red and early Quaternary in blue.