Postseismic deformation models for the July 2019 Ridgecrest earthquakes: Applications of the SCEC Community Rheology Model

Elizabeth H. Hearn, & Charles A. Williams

Published August 15, 2019, SCEC Contribution #9806, 2019 SCEC Annual Meeting Poster #242 (PDF)

We are developing finite-element models to forward calculate early postseismic deformation following the Ridgecrest earthquake sequence. Our goals are to (1) compare modeled surface velocities with postseismic velocity data as they become available, (2) assess how the preliminary CRM performs, particularly with regard to predicting intermediate- to far-field deformation, and (3) assess sensitivity of modeled coseismic and postseismic fault stresses and afterslip to variations in material properties and coseismic slip distribution. The models are being developed using two codes: GAEA (Saucier and Humphreys, 1993) and PyLith v. 2.2.1 (Aagaard et al., 2013). Both models are based on the same unstructured mesh geometry, and incorporate preliminary Ridgecrest and Searles Valley earthquake rupture geometries and slip distributions. The GAEA model incorporates afterslip with parameters from Hearn and Thatcher (2015) model 3DSZ6, and power-law ductile flow in the lower crust and upper mantle based on the preliminary CRM and CTM. The PyLith model will incorporate the CRM via spatial database files that may be shared with other PyLith users in the deformation modeling community, and which may be extended to 3D as the Geologic Framework evolves. 3D elasticity inferred from the SCEC CVM will also be represented in the PyLith model. Going forward, the PyLith model may be extended to include a more detailed representation of the subsurface than the GAEA model, which has size limitations. At the 2019 SCEC annual meeting, we plan to present GAEA forward models with afterslip and ductile rheologies based on the CRM, as well as comparisons of the PyLith and GAEA models for select coseismic and postseismic model cases.

Key Words
Community Models, rheology

Citation
Hearn, E. H., & Williams, C. A. (2019, 08). Postseismic deformation models for the July 2019 Ridgecrest earthquakes: Applications of the SCEC Community Rheology Model. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Ridgecrest Earthquakes