The Uniform Earthquake Rupture Forecast Version 2

The probability of a M>6.7 earthquake in the next 30 years calculated using the UCERF.

The Working Group on California Earthquake Probabilities (WGCEP) has developed a statewide earthquake-rupture forecast that uses “best available science”. This model, called the Uniform California Earthquake Rupture Forecast version 2 (UCERF2), is the product of a collaborative project of the U.S. Geological Survey (USGS), the California Geological Survey (CGS) and the Southern California Earthquake Center (SCEC) with the assistance of the California Earthquake Authority (CEA). Development of this model was tightly coordinated with the USGS National Seismic Hazard Mapping Program (NSHMP). For this project, the WGCEP has assembled and analyzed the latest data on the rates of earthquake occurrence from historic and instrumental data, paleoseismology, slip rates on faults, and deformation rates from GPS and long-term plate-tectonic models. The resulting model achieves an unprecedented degree of agreement with all the available data and can be used to calculate future earthquake hazards. The model is being used by NSHMP to calculate the long-term (time-independent) earthquake shaking hazards used in   the development of building codes. It also is being used to calculate the time-dependant hazard (which depends on how recently earthquakes have occurred on specific faults) that is used to calculate earthquake probabilities for the next 30 years. CEA will use this time-dependent model to analyze potential earthquake losses and set earthquake insurance premiums.  The report of the WGCEP, detailing the development of the UCERF and providing background data and analyses, is published as CGS Special Report 203 and USGS Open File Report 2007-1437, and as SCEC Contribution 1138.

Special Report 203, The Uniform California Earthquake Rupture Forecast.

Download Special Report 203 (PDF Document, 11.2 MB).


A.California Fault Parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007, by C. J. Wills, R. J. Weldon II, and W. A. Bryant
B.Recurrence Interval and Event Age Data for Type A Faults, by T. E. Dawson, R. J. Weldon II, and G. P. Biasi
C.Monte Carlo Method for Determining Earthquake Recurrence Parameters from Short Paleoseismic Catalogs: Example Calculations for California, by T. Parsons
D.Magnitude-Area Relationships, by R.S. Stein
E.Overview of the Southern San Andreas Fault Model, by R. J. Weldon II, G. P. Biasi, C. J. Wills, and T.E. Dawson
F.Summary of Geologic Data and Developments of A-Priori Rupture Models for the Elsinore, San Jacinto, and Garlock Faults, by T. E. Dawson, T. K. Rockwell, R. J. Weldon II, and C. J. Wills
G.Development of Final A-Fault Rupture Models for WGCEP/NSHMP Earthquake Rate Model 2.3, by E. H. Field, R. J. Weldon II, V. Gupta, T. Parsons, C. J. Wills, T. E. Dawson, R. S. Stein, and M. D. Petersen
H.WGCEP Historical California Earthquake Catalog, by K. R. Felzer and T. Cao
I.Calculating California Seismicity Rates, by K. R. Felzer
J.Spatial Seismicity Rates and Maximum Magnitudes for Background, by M. D. Petersen, C. S.
Mueller, A. D. Frankel, and Y. Zeng

K.A-Priori Rupture Models for Northern California Type-A Faults, by C. J. Wills, R. J. Weldon II, and E. H. Field
L.Cascadia Subduction Zone, by A. D. Frankel and M.D. Petersen
M.Empirical Estimation of Regional Time Variation in Seismicity, by K. R. Felzer
N.Conditional, Time-Dependent Probabilities for Segmented Type-A Faults in the WGCEP UCERF 2, by E. H. Field and V. Gupta
O.Paleoseismic Investigations of the Walnut Site on the San Jacinto Fault, by T. E. Fumal and K. J. Kendrick
P.Compilation of Surface Creep on California Faults and Comparison of WGCEP 2007 Deformation Model to Pacific-North America Plate Motion, by B. A. Wisely, D. A. Schmidt, and R. J. Weldon II

Supplementary Materials

A. Supplementary Excel Spreadsheet
Sheet 1) Rupture Magnitudes & Rates
Sheet 2) Total 30-year Rupture Probabilities
Sheet 3) Total 5-year Rupture Probabilities
Sheet 4) M≥6.7 30-year Rupture Probabilities
Sheet 5) Segment Rates & Mean Recurrence Intervals
Sheet 6) Total 30-year Segment Probabilities
Sheet 7) Total 5-year Segment Probabilities
Sheet 8) M≥6.7 30-year Segment Probabilities
Sheet 9) M≥6.7 Probabilities in WGCEP (2003) Box
Sheet 10) Total 30-year Probabilities on Faults
Sheet 11) M≥6.7 30-year Probabilities on Faults
Sheet 12) B-Fault Data
Sheet 13) Region Polygons