2008 Sichuan earthquake
-Surface Displacement along the Longmenshan Fault Zone- Differential Interferometric SAR (DInSAR) Analysis

The Sichuan Earthquake, which occurred in Sichuan Province, China, on May 12, 2008, was caused by the activity along the Longmenshan Fault, which extends over 200 km, resulting in widespread and devastating damage. Figure 1 shows the differential interferogram around the northern part of the Longmenshan Fault. Figure 2 converts the interferogram phase into satellite‘s line-of-sight displacement, with shortening exceeding 60 cm in some areas (shown in red). The blue areas on the northern block of the fault (indicated by red arrows) corresponds to moving away from the satellite (eastward), while the yellow to red areas indicate moving toward the satellite (westward). This indicates that the fault activity involved right-lateral strike-slip motion in addition to vertical displacement. Figure 3 shows coherence, a measure obtained during InSAR processing. Coherence decreases where surface conditions have changed between the two observations. North of the inferred Longmenshan Fault, coherence is significantly lower than to the south, indicating that the surface of the northern block (the hanging wall) was severely disturbed by the earthquake. Beichuan Prefecture (located almost in the center of the figure), which suffered from extremely severe damage, is located almost directly above the fault, as can be clearly inferred from this figure.