SCEC Award Number 11167 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Survey for New Precarious Rocks Important for Testing Cybershake, NGA, and Hazard Maps
Investigator(s)
Name Organization
James Brune University of Nevada, Reno
Other Participants
SCEC Priorities B2, B4, C SCEC Groups SHRA, Seismology, GMP
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 It has become clear that precariously balanced rocks (PBRs) provide important constraints on ground motion attenuation curves and seismic hazard. Because obtaining a statistically sufficient number of near-source instrumental recordings from very large earthquakes in a variety of tectonic environments may take many decades, precariously balanced rocks which have been in place thousands of years provide important constraints on ground motion attenuation curves and seismic hazard, as well as new methods of computing broad band seismograms (Cybershake). Support for the old age of the rocks has been provided by cosmogenic age dating. Previous results from SCEC funding are strong evidence that PBRs provide important constraints for all of the new tools for estimating earthquake hazard. We have developed advanced photometric methods of documentation of PBR shapes. The PI and assistant carried out surveys to locate and document new PBRs in areas critical for constraining results of the new seismic hazard tools. Rocks in fourteen areas have been photographed and several of these turned into digital photomodels of the rocks. Important results from these surveys are given in final reports of other SCEC reports.
Intellectual Merit 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 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.
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