SCEC Award Number 17065 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Estimating seismic coupling in southern California using aftershock productivity and geodetic constraints
Investigator(s)
Name Organization
Ilya Zaliapin University of Nevada, Reno Corné Kreemer University of Nevada, Reno Yehuda Ben-Zion University of Southern California
Other Participants Two graduate students (one at each institution): USC -- Yifang Cheng, UNR -- TBN
SCEC Priorities 1c, 3d, 2a SCEC Groups SDOT, Geodesy, Seismology
Report Due Date 06/15/2018 Date Report Submitted 05/29/2018
Project Abstract
 The goals of the project are to (i) explore the connection between seismic coupling and aftershock productivity suggested by the damage rheology modeling for estimating the seismic coupling in southern California, and (ii) obtain additional constraints on the seismic coupling estimation using geodetic modeling. The projects uses and further develops the earthquake cluster technique and geodetic modeling products developed by the PIs. The project resulted in a new approach to estimating the coupling, an improved earthquake cluster/declustering methodology, and a suit of findings related to detecting and quantifying seasonal changes in earthquake cluster and strain properties, as well as the existence of earthquake clusters of different types with distinct productivity characteristics.
Intellectual Merit The project develops a systematic analysis of the connections between seismic coupling and properties of aftershock series within a formalism associated with a physical model and combining statistical analysis of earthquake catalogs with geodetic information. Improved understanding of the effects of physical and ambient properties of the crust on fault loading process and partition of the accumulated seismic moment among seismic and aseismic processes is recognized among the fundamental problems of earthquake physics by SCEC5.
Broader Impacts The project obtains a suit of results that have an impact on research areas outside of the immediate project scope. The project develops a novel method for earthquake catalog declustering; documents non-stationary dynamics of seismic moment release on a global scale; reports seasonal variations of strain rates; and quantifies different types of earthquake clusters with distinct productivity properties.
Exemplary Figure Figure 2: Time fluctuations of the global seismic moment release: an illustration. The analysis uses 692 declustered earthquakes with Mw>7 during 1918 – 2014 from version 4 of the ISC-GEM catalog. (a) Examined events (gray circles) and the estimated corner moment Mc of tapered Pareto distribution (solid line) as a function of time. The estimation is done in a sliding window of 100 events. A lower 95% confidence boundary is shown by dashed line; the upper limit is unconstrained. (b) The observed moment release in a sliding window of m = 100 events (solid line) vs. empirical quantiles (dashed lines) obtained using 10^5 resamplings of the observed moments. The level of quantiles in indicated in the figure. After Zaliapin and Kreemer, 2017.

Zaliapin, I. and C. Kreemer (2017) Systematic fluctuations in the global seismic moment release. Geophys. Res. Lett., 44, 4820-–4828, doi:10.1002/2017GL073504