HR: 0800h
AN: G51C-0627    [Abstracts]
TI: Application of Maximum Likelihood PSInSAR to Subsidence Monitoring in the Geothermal Fields of Imperial Valley, California
AU: Eneva, M
EM: meneva@imageair-inc.com
AF: ImageAir Inc., 10513 Caminito Westchester, San Diego, CA 92126, United States
AU: * Agram, P S
EM: shanker@stanford.edu
AF: Depts of Electrical Engg. and Geophysics, 350 Serra Mall, Packar 302, Stanford, CA 94305, United States
AB: Persistent Scatterer (PS) InSAR methods are among the most successful new methods using a stack of interferograms to extract deformation time series in regions where traditional InSAR is limited. In particular, the PSInSAR technique performs significantly better in vegetated areas. We have been developing a Maximum Likelihood PS (ML-PS) method in an attempt to improve on earlier PS techniques, such as StaMPS (Hooper et al., 2003) and Permanent Scatterers Technique (Ferretti et al., 2000). The ML-PS method works by estimating the most likely signal-to-clutter ratio (SCR) of each pixel by comparing the interferometric phase time-series against mathematical models describing the interferometric phase as a function of the SCR. We have already successfully used the ML-PS method in the vegetated regions of the Bay Area in California (Shanker and Zebker, IGARSS 2007). Here we extend this work to estimate the surface deformation, mostly subsidence, in the Imperial Valley region of southern California. The reasons for this subsidence may be tectonic, as well as related to geothermal production in three geothermal fields – Salton Sea, Heber, and East Mesa. Of these, Salton Sea and Heber are inundated with agricultural fields, rendering conventional InSAR methods ineffective. While surface subsidence is a well known phenomenon in geothermal fields all over the world, it has not caused significant problems in the Imperial Valley region. However, it may increase in the next decade due to enhanced geothermal production, and its monitoring is thus of increasing importanc. We will present 1992-2000 results based on the analysis of ERS SAR data from the WINSAR archive. These results will be compared with 2004-2007 results from the analysis of ENVISAT data, using both ascending and descending tracks. It will be demonstrated that our ML-PS method identifies a denser network of PS in the region compared to the other known PS methods. The results from the PSInSAR analysis will be compared with leveling data provided by the geothermal operators. We intend to demonstrate the effectiveness of the new PS-InSAR method to monitor the deformation due to geothermal extraction in vegetated regions.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1209 Tectonic deformation (6924)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
SC: Geodesy [G]
MN: 2007 Fall Meeting