A regionalized seismicity model for subduction zones based on geodetic strain rates, geomechanical parameters and earthquake-catalog data

José A. Bayona Viveros, Sebastian von Specht, Anne E. Strader, Sebastian Hainzl, Fabrice Cotton, & Danijel Schorlemmer

Published August 15, 2019, SCEC Contribution #9692, 2019 SCEC Annual Meeting Poster #036 (PDF)

The Seismic Hazard Inferred from Tectonics based on the Global Strain Rate Map (SHIFT_GSRM) earthquake forecast was designed to provide high-resolution estimates of global seismicity to be used for seismic hazard assessment. This model combines interseismic strain rates with global earthquake parameters to characterize long-term rates of seismic moment and earthquake activity. During the 1977-2009 period, the model properly computes earthquake rates in seismically active continental regions. However, the uncorrected forecast underestimates seismicity rates in subduction zones by an average factor of approximately 3, presumably due to the use of inappropriate geometric parameters.

We present a complementary method to SHIFT_GSRM to more accurately compute earthquake rates in 37 subduction segments, based on the conservation of moment principle and the employment of regional interface seismicity parameters, such as subduction dip angles, corner magnitudes, and coupled seismogenic thicknesses. In six progressive steps, we find that SHIFT_GSRM earthquake-rate underpredictions mainly stem from the utilization of a global probability function of seismic moment release that poorly captures the great variability among subduction megathrust interfaces.

The Subduction Megathrust Earthquake Rate Forecast (SMERF) is consistent with the observations during the 1 January 1977 to 31 December 2014 retrospective period. Moreover, successful pseudoprospective evaluations for the 1 January 2015 to 31 December 2018 period demonstrate the initial power of SMERF to properly estimate subduction-zone seismicity. Nonetheless, independent prospective tests are necessary to more reliably describe the forecasting capacity of the regionalized earthquake-rate model

Finally, we integrate SMERF estimates in subduction zones with SHIFT_GSRM computations elsewhere to generate a revised global geodetic-based earthquake model, referred to as the Tectonic Earthquake Activity Model (TEAM) seismicity forecast. TEAM is created to actively contribute to the development, update and improvement of global hybrid seismicity models like the Global Earthquake Activity Rate (GEAR1) forecast.

Key Words
subduction zones, seismicity model, regionalized, interseismic strain rates

Citation
Bayona Viveros, J. A., von Specht, S., Strader, A. E., Hainzl, S., Cotton, F., & Schorlemmer, D. (2019, 08). A regionalized seismicity model for subduction zones based on geodetic strain rates, geomechanical parameters and earthquake-catalog data. Poster Presentation at 2019 SCEC Annual Meeting.

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