SAR observations
An interferogram was produced from ERS-1 SAR data for frames obtained for November of 1993 and December of 1995. The time period is close to the time period of the GPS data. The SAR data correlated well in the San Fernando Valley where much of the deformation from the Northridge earthquake took place. Decorrelation occurred inthe hills to the north of the valley. SAR observations are present at the locations of the GPS stations, although an unwrapping error causes the value at CSUN to be suspect. More careful analysis will correct this problem.
Comparison with GPS results
The interferogram shows a combination of the coseismic and postseismic crustal deformation signal. We subtracted a synthetically generated interferogram of the model of Wald and Heaton (1996) to produce and image of the postseismci deformation. In these images we show their combined model. We also produced a synthetic interferogram using a slightly different (earlier) GPS inversion than the one shown on this poster. We scaled the magnitude of the observations according to the logarithmic fit to the data. The inversion and postseismic SAR observations are qualitatively similar. We see deformation over the rupture plane and to the west of the rupture. The magnitude of the deformation is similar in both cases.