Earthquake Potential in California-Nevada Implied by Correlation of Strain Rate and Seismicity

Yuehua Zeng, Mark D. Petersen, & Zheng-Kang Shen

Published August 15, 2017, SCEC Contribution #7874, 2017 SCEC Annual Meeting Poster #016

Rock mechanics studies and dynamic earthquake simulations show that patterns of seismicity evolve with time through: (1) accumulation phase, (2) localization phase, and (3) rupture phase. We observe a similar pattern of changes in seismicity during the past century across California and Nevada. To quantify these changes, we correlate GPS strain rates with seismicity. Earthquakes of M>6.5 are collocated with regions of highest strain rates. By contrast, smaller magnitude earthquakes of M≥4 show clear spatiotemporal changes. From 1933 to the late 1980s, earthquakes of M≥4 occurred in both high and low strain rate regions (corresponding to the accumulation phase). From the late 1980s to 2016, earthquakes were more concentrated within the high strain rate areas focused on the major fault strands (corresponding to the localization phase). In the same time period, the occurrence rate of M>6.5 events also increased significantly in the high strain rate areas. To further justify the significance of our findings, we examine catalog completeness, errors in the cumulative seismicity and strain rate, declustering algorithms, magnitude uniformity, location uncertainties, influence of the creeping section, etc. Given that several segments of the San Andreas Fault are approaching or exceeding their mean recurrence times, our analysis suggests that the fault system may be entering a period of increased risk for large earthquakes in California (rupture phase).

Key Words
GPS Strain Rate, Seismicity, Large Earthquake Rutpure

Citation
Zeng, Y., Petersen, M. D., & Shen, Z. (2017, 08). Earthquake Potential in California-Nevada Implied by Correlation of Strain Rate and Seismicity . Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)