SCEC Award Number 11162 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Precariously Balanced Rock Orientations and Fragilities Compared with Cybershake Waveforms: Implications for Seismic Hazard and Possible Super-Shear Ruptures
Investigator(s)
Name Organization
James Brune University of Nevada, Reno
Other Participants Jordon, Tom
SCEC Priorities B2, B4, C SCEC Groups SHRA, Seismology, GMP
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 Precariously Balanced Rock Orientations and Fragilities Compared with Cybershake Waveforms: Implications for Seismic Hazard and Possible Super-Shear Ruptures.

Earthquake recurrence forecasting has steadily improved in recent years. Similarly the numerical power for calculating seismic ground motion, based on various types of modeling and assumed input parameters, have greatly improved (regression methodologies. tera and peta scale computing, Cybershake broad-band waveforms). The weak link in proceeding to final estimates of seismic hazard is the validation of the various inputs and modeling procedures. There are simply not enough instrumental data from large earthquakes near-source, to validate the various programs and assumed source parameterizations. The study of precariously balanced rocks (PBRs) may be the only way to remedy the situation. In 2011 we studied critical rocks in the UNR archive of thousands of PBRs, rocks strategically selected to be most useful in constraining the next generation of seismic hazard maps. The advent of Cybershake ground motion calculations offers the possibility of developing a better understanding of the distribution of PBRs and PBR orientations. Dozens of PBRs in a number of areas in Southern California have been photographed for the Photomodeler computer program to produce digital shapes for use in further analysis. Of the rocks involved, approximately 20 have already been modeled to produce digital 3-D shape models. Of these, about 10 are in the present Cybershake broad band coverage area, and are being investigated by Jessica Donavan andTom Jordan at USC, and James Brune at UNR. Preliminary result are very encouraging, and indicate that future studies will greatly improve our understanding of earthquake hazard, a major step forward for further research in SCEC4.
Intellectual Merit The Precariously Balanced Rock (PBR) methodology is at the forefront of research in understanding seismic hazard. This is because the instrumental record of ground motion in earthquakes is very short (hundreds of years) whereas we need to know the probabilities of damaging ground motion at random return periods of thousands of years. The PBRs have been in place thousands of years and thus provide a needed constraint. This cutting-edge methodology has only been developed in the last couple of decades, primarily as a SCEC project, and is now being used to test and validate the latest tools in estimating earthquake hazard
Broader Impacts The PBR methodology will have a broad impact on society because it will affect design of buildings in seismic areas far into the future. Depending on results, the impact could involve billions of dollars in damage, and thousands of lives, both in developed and developing countries. In sum, it will greatly help in understanding earthquake hazard and the consequent social changes necessary for appropriate mitigation.
Exemplary Figure Couldn't get pictures to go here.
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