Wavelet Analysis of the Potential Fields of Elasticity: a Remote Sensing Tool to Monitor Steam Cap Migrations?

A technology based upon analyses of InSAR surveys of incremental deformations over an operating geothermal field is emerging that might serve to monitor steam cap migrations on a timescale of weeks. Based upon theory developed in Horowitz and Hornby (in prep.), one can compute a harmonic potential field that has dilatational sources and sinks from 3 component surface displacement increment surveys. In the context of a water-steam fluid in porous rocks, steam filled material will have significantly different bulk moduli from water-filled material. In the presence of a regional stress field, changes in the pore-filling will appear as dilatational sources or sinks. There are commercial InSAR satellites in operation (e.g. Canada's Radarsat-1 and Radarsat-2), and a research system (ALOS PALSAR from Japan) is in orbit with L-band capabilities that can penetrate vegetation canopies. Imaging geometries may be problematic for computing three component displacement surveys over any given area, but we have successfully solved for the 3component field in the case of afterslip from the 2003 Bam, Iran earthquake. We believe that this technology might be a cost-effective and higher sampling rate alternative/supplement to microgravity surveying for monitoring the migration of steam caps in an operating geothermal field.