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A Fault-Based Crustal Deformation Model With Deep Driven Dislocation Sources for the 2023 Update to the US National Seismic Hazard Model

Description: 

We apply a fault-based crustal deformation model with deep driven dislocation sources to estimate long-term on-fault geodetic slip-rates and off-fault moment rate distribution in the Western United States (WUS) for the 2023 update to the National Seismic Hazard Model (NSHM). This model uses the method of Zeng and Shen (2017) to invert for slip-rate and strain-rate parameters based on inputs from global positioning system (GPS) velocities and geologic slip-rate constraints. The model connects adjacent major fault segments in California and the Cascadia subduction zone to form blocks that extend to the boundaries of the study area. Faults within the blocks are obtained from the NSHM geologic fault model. The geodetic slip rates are determined using a least-squares inversion with a normalized chi-square of 6.6. We also apply a time-dependent correction called “ghost transient” effect to the data to account for the viscoelastic responses from large historic earthquakes along the San Andreas Fault and Cascadia subduction zone. Major discrepancies between geodetic slip rates and geologic slip rates along the San Andreas Fault, for example, from the Cholame to the Mojave and San Bernardino segments of the San Andreas, are well-resolved after we apply the ghost transient correction to GPS velocities. Off-fault moment rate distribution is consistent with regional tectonics and seismicity patterns with a total rate of 1.6x10¹⁹ N˖m/year for the WUS.

Session: USGS National Seismic Hazard Models: 2023 and Beyond

Type: Oral

Date: 4/18/2023

Presentation Time: 08:45 AM (local time)

Presenting Author: Yuehua Zeng

Student Presenter: No

Invited Presentation: 

Authors