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InSAR Data Shows Evidence of Coseismic Deformation - Gulf of CA Earthquake, August 3, 2009

Across the central Gulf of California the Pacific-North America plate boundary is localized in the Ballenas channel, which separates Isla Angel de la Guarda from the Baja California Peninsula (BAJA). At about 45 mm/yr, the Ballenas Transform represents a fast moving strike-slip fault. On August 3rd a 6.9 M earthquake occurred on this fault. Although the epicenter of the earthquake is hidden under water, InSAR data from Envisat satellite (2004-06-24 to 2009-08-24) shows clear evidence of the coseismic deformation on mainland BAJA and Isla Angel de la Guarda (about 7-8 fringes, each with 2.8 cm line-of-sight deformation). The InSAR data is used to infer the earthquake source mechanism, using episodic GPS data to constrain the total offset across the Ballenas channel.

GPS record of ice surface elevation changes (brown symbols, left scale) and the rate of elevation change (green lines, right scale) above subglacial Lake Mercer. The rate of elevation change was averaged for 20-day intervals; uncertainties are shown by error bars as one standard error.

Figure 1 - InSAR image provided by Christina Plattner, Ludwig-Maximilians University, Munich, Germany, Falk Amelung, University of Miami, InSAR Laboratory, Rocco Malservisi, Ludwig-Maximilians University, Munich, Germany, and Tim Dixon, University of Miami, InSAR Laboratory.


Last modified: 2020-01-28  22:54:20  America/Denver