Crustal deformation associated with the Mw7.2 2010 El Mayor-Cucapah earthquake from GPS

geodesy2011 SCEC Annual Meeting

Joshua Spinler, Richard Bennett, Javier Gonzalez-Garcia, and Chris Walls

Outline GPS Data Processing

Time series analysis Deformation associated

with the M7.2 El Mayor-Cucapah and M5.7 Southern California earthquakes of 2010

New PBO-Mexico CGPS network

Photo taken by John Fletcher, CICESE

PBO Site PLTX

Southern California

CGPS•102 CGPS sites located within 250 km of EMC earthquake•Sites part of both PBO and SCIGN CGPS Networks• Seismicity for period 4/4/2011 – 6/15/2011 (from E. Hauksson)

Time Series Analysis

M7.2 El Mayor Cucapah EQ

M5.7 Southern California EQ

Time Series Analysis

M7.2 El Mayor Cucapah EQ

M5.7 Southern California EQ

Time Series Analysis

Constrained Random Search method Brachetti et al. 1997, Journal of Global Optimization

Finds the minimum of a multi-variable function Simultaneously solve for 22 different parameters using an

exponential decay function Parameters: Initial offset, Velocity, Annual and Semi-annual

perturbations, Coseismic displacement, Postseismic deformation, exponential decay time

Minimize misfit to the horizontal coordinate time series data (NRMS)

Time Series Analysis – Site P481

Time Series Analysis – Site P481

NRMS = 0.68

Time Series Analysis – Site P494

Time Series Analysis – Site P494

NRMS (P494) = 1.20

Mean NRMS for all sites = 0.76

Coseismic displacementApril 4, 2010

M7.2 El Mayor-CucapahSITE Displacement

(mm)MEXI 221.70P494 213.81P496 194.38P497 104.09P744 92.57P500 91.98

Coseismic displacement

June 15, 2010M5.7 Southern

CaliforniaSITE Displacement (mm)

P481 11.41P492 9.07P494 8.27P480 6.80P066 6.13

Exponential Decay Time

Mean decay time (EMC) = 629 ± 75 days Mean decay time (SoCal) = 682 ± 67 days Viscosity (η) = τμ = 1.6 x 1018 Pa-s

Relatively weak lower crust and/or upper mantle

Conclusions

Using the CRS method allows for detailed analysis of complicated GPS coordinate time series data

Future work: Fault slip modeling and analysis of postseismic deformation signal

Include campaign GPS spanning the earthquakes from northern Baja

PBO in Baja California•Locations for sites strategically chosen to best resolve postseismic deformation patterns and lower crustal/upper mantle rheology

PBO in Baja California

Site PLPXInstalled 10/27/10

PBO in Baja California

Site PALXInstalled 9/2/10

PBO in Baja California

Installed 10/29/10Installed 8/30/10

Installed 4/27/11

Installed 2/11/11

Funding for these projects provided by NSF and SCEC

Seven new CGPS sites installed in northern Baja California, Mexico, and the data is available online at www.unavco.org