Geodetic moment accumulation and seismic release in northern Baja California, Mexico

Alejandro Gonzalez-Ortega, Jose Javier Gonzàlez-Garcìa, & David T. Sandwell

Published August 12, 2016, SCEC Contribution #6689, 2016 SCEC Annual Meeting Poster #155

We have analyzed all available GPS data from northern Baja California, Mexico, covering the period 1993-2008, in order to estimate the strain rate and seismic moment accumulation rate during the interseismic period prior to the 2010, Mw 7.2 El Major-Cucapah earthquake. The analysis shows concentrations of strain-rate and moment-rate along the Imperial and Cerro Prieto Faults extending from the Salton Sea to the Gulf of California. The regional moment accumulation based on geodesy (M ̇_o^g= 3.0±0.3x1018Nm/yr) is significantly greater than the corresponding moment release rate by earthquakes (M ̇_o^s=1.2x1018 Nm/yr), so in 2008 the region had a residual moment of Mo= 2.1x1020 Nm, equivalent to an Mw7.4 earthquake. Much of this excess moment was released by the 2010, Mw7.2 El Mayor-Cucapah earthquake; the remaining residual moment of the Imperial and Cerro Prieto faults corresponds to a maximum Mw6.8 according to the Gutenberg–Richter law with b-value of 1.0. In contrast, the seismic moment released on the San Miguel fault, primarily from the earthquake swarm occurred in 1954-1956 Mw<=6.8, is one order of magnitude higher than the accumulated geodetic moment. These new estimates of seismic moment potential provide important constraints on earthquake forecasts for the southern San Andreas Fault System.

Key Words
strain rates, geodetic moment rates, seismic release

Citation
Gonzalez-Ortega, A., Gonzàlez-Garcìa, J., & Sandwell, D. T. (2016, 08). Geodetic moment accumulation and seismic release in northern Baja California, Mexico. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy