Hi Tony. To a certain extent they are using it in the manner you suggested. This is how they discovered the bulge near the Three Sisters Volcano in Oregon.

The USGS scientists discovered the bulge through the use of InSAR. The images that revealed the 10-centimeter uplift near South Sister were obtained in 1996 and 2000. The exact timing of the uplift, or whether it is continuing at present, is unknown, but is being studied further.

At present, earthquake activity and gas emissions appear to be at or near background levels. In order to be prepared to more accurately detect possible precursors and to better understand this uplift phenomenon, USGS plans to enhance the existing monitoring network. Installation of one or more seismometers and a Global Positioning System (GPS) receiver, resurvey of existing benchmarks and installation of new benchmarks should be able to do a better job of monitoring the area then InSAR. Take Care…Don in creepy town