Concept for the subresolution measurement of earthquake strain fields using SPOT panchromatic imagery

The use of satellite-derived imagery for measuring subresolution horizontal terrain displacments associated with present-day earthquakes is discussed with reference to data from the French SPOT satellite whose sensor array provides 10-m panchromatic imagery. The measured terrain displacements can be up to several meters, but usually no more than 6-8 m even for major earthquakes. The general approach is to spatially match the after image to the before image at each point on a half-kilometer grid by iteratively interpolating one and testing its correlation with the other. The discussion covers the basic algorithm, results of initial tests, error types and limitations, and future work.