Johnson 9417908 The PIs will study how well various configurations of surface displacement measurements can constrain estimates of subsurface fault slip, with particular attention to the determination of coseismic fault motion. With the burgeoning use of new techniques for surface displacement measurement-notably GPS and more recently SAR interferometry-an investment in how best to conduct these measurements in advance of anticipated earthquakes should pay off in a better understanding of the earthquake process and of earth structure models near these faults once the earthquakes occur. ****