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Interferogram formation in the presence of complex and large deformation

January 1, 2007

Sierra Negra volcano in Isabela island, Galápagos, erupted from October 22 to October 30 in 2005. During the 8 days of eruption, the center of Sierra Negra's caldera subsided about 5.4 meters. Three hours prior to the onset of the eruption, an earthquake (Mw 5.4) occurred, near the caldera. Because of the large and complex phase gradient due to the huge subsidence and the earthquake, it is difficult to form an interferogram inside the caldera that spans the eruption. The deformation is so large and spatially variable that the approximations used in existing InSAR software (ROI, ROI_PAC, DORIS, GAMMA) cannot properly coregister SAR image pairs spanning the eruption. We have developed here a two-step algorithm that can form intra-caldera interferograms from these data. The first step involves a "rubber-sheeting" SAR image coregistration. In the second step we use range offset estimates to mitigate the steep phase gradient. Using this new algorithm, we retrieve an interferogram with the best coverage to date inside the caldera of Sierra Negra.

Publication Year 2007
Title Interferogram formation in the presence of complex and large deformation
DOI 10.1029/2007GL029745
Authors S.-H. Yun, H. Zebker, P. Segall, A. Hooper, Michael P. Poland
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70029809
Record Source USGS Publications Warehouse
USGS Organization Hawaiian Volcano Observatory; Volcano Hazards Program