| Abstract |
Cerro Prieto is the oldest and largest Mexican geothermal field in operation and has been producing electricity since 1973. The large amount of geothermal fluids extracted to supply steam to the power plants has resulted in considerable deformation in and around the field (Glowacka et al., 1999, 2005; Sarychikhina et al., 2011). The deformation includes land subsidence and related ground fissuring and faulting. These phenomena have produced severe damages to the local infrastructure such as roads, irrigation canals and other facilities. Detection of land subsidence and monitoring of the spatial and temporal changes of its pattern and magnitude can provide important information about the dynamics of this process and controlling geological structures. In the past two decades a space remote sensing technique, Differential Synthetic Aperture Radar Interferometry (DInSAR), has demonstrated to be a very effective technique for monitoring the Earth’s surface displacement due to natural hazards and anthropogenic activities. This space-based technique provides unprecedented information on surface deformation, with great spatial and temporal detail, which cannot be achieved by any ground-based technique. The previous works (Carnec and Fabriol (1999) and Hanssen (2001), Glowacka et al., 2010a, Sarychikhina, 2010; Sarychikhina et al., 2011) have demonstrated the capability and limitations of conventional two-pass DInSAR technique for measuring the subsidence at Cerro Prieto Geothermal Field (CPGF). In this paper, DInSAR stacking method is applied in order to investigate the ground deformation in and around the CPGF. C-band ENVISAR ASAR images acquired between 2003 and 2009 from the ascending and descending tracks, obtained from the European Space Agency (ESA), as part of ESA CAT-1 project (ID - C1P3508), were used. Gamma ISP and DIFF/GEO software packages were used to calculate differential interferograms from Single Look Complex (SLC) data and for differential interferograms stacking (Wegmüller and Werner, 1997). The resultant average annual deformation rate maps for 2004 - 2007 and 2009 were analyzed. The annual deformation rate maps (from ascending and descending tracks) for 2008 were excluded from the analysis because of presenting strong co-seismic deformation signals. The changes in the deformation pattern and rate were identified. The results of this study are compared with those from previous studies. |