SCEC Award Number 12059 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Effects of Heterogeneities on Earthquake Statistics
Investigator(s)
Name Organization
Karin Dahmen University of Illinois at Urbana-Champaign Yehuda Ben-Zion University of Southern California
Other Participants Braden Brinkman (graduate student)
SCEC Priorities 3c, 5d, 2b SCEC Groups Seismology, FARM, EFP
Report Due Date 03/15/2014 Date Report Submitted N/A
Project Abstract
 Using a simple model for earthquake statistics, we have computed the earthquake statistics as a function of the amnount of spatial heterogeneities in a fault zone. We computed the frequency magnitude statistics and the interevent time distributions for this model and compared the results to observations and other models. We also computed the susceptibility of the fault to periodic loading stresses and tested a new method to predict large model earthquakes, using these results. We found good agreement of our model predictions with recent observations on earthquake statistics.
Intellectual Merit The spatial heterogeneity of material properties along fault zones affects the statistical measures of seismicity patterns, such as the earthquake size distribution and inter event times. We have developed a model and use tools from statistical physics to tackle these issues analytically and with simulations. With these tools we have computed the distribution of earthquake sizes, as a function of the amount of spatial (brittle or geometrical) heterogeneities in a fault zone. We also computed the inter event times expected for the same model. We use the model to compute probabilities of large earthquakes from correlations between the timings of small earthquakes and periodic fault stresses, such as tidal or seasonally varying loadings. Despite the simplicity of the model, we find good agreement with the observed trends of correlations of real earthquake data with tidal stresses.
Broader Impacts Two graduate students and two undergraduate students were trained in interdisciplinary research. Through this project they learned to use modern tools from statistical physics, seismology, and mechanical engineering. They received training in presentation skills, and communication skills, through the collaboration between earth scientists and physicists, both in theory and experiment. The results of the work were presented in invited talks at numerous conferences, and in a series of seminar talks. Several papers on the results have been submitted for publication.
Exemplary Figure Unfortunately I cannot post the most exciting figures because they are part of a pending paper that has been submitted to a high impact journal. As far as I know, this report will be published online, and may thus put our submitted paper at risk. We would be happy to add the figure later, after publication, if that would be possible ? Thank you very much, best wishes, Karin Dahmen.