Space-based Tectonic Modeling in Subduction Areas Using PSInSAR

Abstract

While the application of InSAR (INterferometric Synthetic Aperture Radar) techniques to seismology has been well known since the mid-1990s (Massonnet et al. , 1993; Massonnet et al. , 1996), PSInSAR is generally unfamiliar to the Earth science community. The PS stands for “permanent scatterer”, and it is the use of these (along with the volume of scenes employed) that distinguishes the method from more familiar InSAR techniques. A permanent scatterer is any persistently reflective pre-existing ground feature, such as building roofs, metallic structures, and even large boulders. The use of these features offers the possibility of measurements of ground displacements to a degree of accuracy, and over periods of time, previously unobtainable from conventional interferometry. Furthermore, it is possible to construct histories of displacements over the full temporal extent of the SAR data archive (started in 1991) for any part of the globe with data coverage. PSInSAR therefore represents the equivalent of a newly discovered, superaccurate, extremely dense GPS network that has been in existence for the last twelve years. The high resolution of PSInSAR data, coupled with its being particularly suited to urbanized areas (numerous buildings, therefore many PS points), makes it an excellent tool for studying things such as urban subsidence (Ferretti et al., 2000; Mizuno and Kuzuoka, 2003; Dehls and Nordgulen, 2004). It also has applications in seismology: as a substitute for GPS data where these do not exist, and as an enhancement where they do. In this paper we report on a pilot project in Japan, the principal aim of which was to calibrate and test the PSInSAR measurements in an area where ground truth is very well established from GPS and leveling data. This work results from a European Space Agency (ESA) “Earth Observation Market Development” project entitled “Developing markets for EO-derived …