Continued Updates, Expansion and Improvements to the Community Fault Model (CFM version 5.3)

Craig Nicholson, Andreas Plesch, Christopher C. Sorlien, John H. Shaw, Scott T. Marshall, & Egill Hauksson

Published August 13, 2019, SCEC Contribution #9509, 2019 SCEC Annual Meeting Poster #323

The Community Fault Model (CFM) is one of the most mature modeling efforts within SCEC, yet it remains critical that the CFM be continually evaluated, updated and improved to more effectively support the wide range of research activities targeted by SCEC5. For 2019, access to the CFM (version 5.2) and its associated fault database was further enhanced through the CFM webpage (https://www.scec.org/research/cfm) and a new, interactive, web-based interface [Su et al., 2019]. In addition, we continue to update, expand and improve the CFM 3D fault set for version 5.3, as well as the underlying datasets used for model evaluation, development, and refinement. This includes expanding the 3D digital elevation models used to define onshore and offshore topography, updating mapped fault surface and seafloor trace files [e.g., Walton et al., 2019], and incorporating both a more complete dataset of linked relocated hypocenter and focal mechanism catalogs (1981–2018) [Hauksson et al., 2012 + updates] and the more extensive QTM catalog [Ross et al., 2019]. In the offshore Santa Maria basin, an integrated dataset of industry marine seismic reflection data and offshore well data was also used to help develop new fault models and refine existing fault geometry [e.g., Sorlien et al., 2015]. As a result of these efforts, new or updated 3D fault representations were added to the CFM in the Offshore Central California fault area (San Gregorio-Hosgri, Lompoc, Purisima, Santa Lucia Bank, West Basin, and Sur faults), in the Great Valley fault area (White Wolf fault), and -- in response to the recent 2019 Ridgecrest-Searles Valley events, in the Sierra Nevada fault area (Eastern Little Lake fault, Southern Little Lake fault) [see Plesch et al., 2019, this meeting]. The expanded and updated catalogs allow us to better characterize and assess the active subsurface 3D fault geometry in complex fault regions. For example, in the Cajon Pass Earthquake Gate Area, focal mechanisms with nodal planes parallel or nearly parallel to the major San Andreas and San Jacinto faults exhibit predominantly strike-slip motion on steeply dipping faults, while additional events farther east provide further evidence for a through-going, steeply dipping San Andreas fault (San Bernardino-Banning strand) through San Gorgonio Pass. These refinements and improvements to 3D fault models continue as relevant data become available, are evaluated, and are integrated into the CFM.

Key Words
CFM v5.3, 3D fault models, Cajon Pass, offshore Central California, Geat Valley, Sierra Nevada, Ridgecrest

Citation
Nicholson, C., Plesch, A., Sorlien, C. C., Shaw, J. H., Marshall, S. T., & Hauksson, E. (2019, 08). Continued Updates, Expansion and Improvements to the Community Fault Model (CFM version 5.3). Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
SCEC Community Models (CXM)