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Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3);the time-independent model

Edward H. Field, Ramon J. Arrowsmith, Glenn P. Biasi, Peter Bird, Timothy E. Dawson, Karen R. Felzer, David D. Jackson, Kaj M. Johnson, Thomas H. Jordan, Christopher Madden, Andrew J. Michael, Kevin R. Milner, Morgan T. Page, Tom Parsons, Peter M. Powers, Bruce E. Shaw, Wayne R. Thatcher, Ray J. Weldon and Yuehua Zeng
Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3);the time-independent model
Bulletin of the Seismological Society of America (June 2014) 104 (3): 1122-1180


The 2014 Working Group on California Earthquake Probabilities (WGCEP14) present the time-independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time-averaged frequency of potentially damaging earthquakes in California. The primary achievements have been to relax fault segmentation and include multifault ruptures, both limitations of UCERF2. The rates of all earthquakes are solved for simultaneously and from a broader range of data, using a system-level inversion that is both conceptually simple and extensible. The inverse problem is large and underdetermined, so a range of models is sampled using an efficient simulated annealing algorithm. The approach is more derivative than prescriptive (e.g., magnitude-frequency distributions are no longer assumed), so new analysis tools were developed for exploring solutions. Epistemic uncertainties were also accounted for using 1440 alternative logic-tree branches, necessitating access to supercomputers. The most influential uncertainties include alternative deformation models (fault slip rates), a new smoothed seismicity algorithm, alternative values for the total rate of M (sub w) > or =5 events, and different scaling relationships, virtually all of which are new. As a notable first, three deformation models are based on kinematically consistent inversions of geodetic and geologic data, also providing slip-rate constraints on faults previously excluded due to lack of geologic data. The grand inversion constitutes a system-level framework for testing hypotheses and balancing the influence of different experts. For example, we demonstrate serious challenges with the Gutenberg-Richter hypothesis for individual faults. UCERF3 is still an approximation of the system, however, and the range of models is limited (e.g., constrained to stay close to UCERF2). Nevertheless, UCERF3 removes the apparent UCERF2 overprediction of M 6.5-7 earthquake rates and also includes types of multifault ruptures seen in nature. Although UCERF3 fits the data better than UCERF2 overall, there may be areas that warrant further site-specific investigation. Supporting products may be of general interest, and we list key assumptions and avenues for future model improvements.

ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 104
Serial Issue: 3
Title: Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3);the time-independent model
Affiliation: U. S. Geological Survey, Denver, CO, United States
Pages: 1122-1180
Published: 201406
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 127
Accession Number: 2014-051926
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 16 tables, geol. sketch maps
N32°30'00" - N42°00'00", W124°30'00" - W114°15'00"
Secondary Affiliation: Arizona State University, USA, United StatesUniversity of Nevada at Reno, USA, United StatesUniversity of California at Los Angeles, USA, United StatesCalifornia Geological Survey, USA, United StatesIndiana University, USA, United StatesUniversity of Southern California, USA, United StatesOregon State University, USA, United StatesLamont Doherty Earth Observatory, USA, United StatesUniversity of Oregon, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201428
Program Name: USGSOPNon-USGS publications with USGS authors
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