Vertical Displacement Distribution of the South Hell Shan Fault at Northeastern Tibetan Plateau Derived from High-Resolution Topographic Data

摘要

Constraining along-fault displacement distribution provides an insight into the rupture process and strain release pattern on the fault, thus enabling us to make more accurate estimates of its potential future behavior. Recently, with the increasing availability of high-resolution stereo satellite images and the DEMs derived from them, both the accuracy and spatial density of the offset measurements can be significantly improved compared to traditional field surveys, which will greatly enhance our understanding of fault behavior. The South Heli Shan fault is an important component of the latest active faults on the northeast margin of the Tibetan Plateau. In this study, we built a 2 m resolution DEM of the South Heli Shan fault based on high-resolution GeoEye-1 stereo satellite images, and then acquired a total of 302 vertical displacement measurements along the fault, increasing the measurement density by nearly a factor of 5 compared to previous field surveys. Based on the displacement clusters on different segments, we conclude that at least four large earthquakes have ever occurred on the South Heli Shan fault, resulting in the variation of cumulative displacements on different geomorphic units. All of these events do not recur as the characteristic earthquake model along the whole fault, but they may follow a characteristic slip pattern on each individual segment.