Constraining the Distribution of Vertical Slip on the South Heli Shan Fault (Northeastern Tibet) From High‐Resolution Topographic Data

Abstract

AbstractReconstruction of the along‐fault slip distribution provides an insight into the long‐term rupture patterns of a fault, thereby enabling more accurate assessment of its future behavior. The increasing wealth of high‐resolution topographic data, such as Light Detection and Ranging and photogrammetric digital elevation models, allows us to better constrain the slip distribution, thus greatly improving our understanding of fault behavior. The South Heli Shan Fault is a major active fault on the northeastern margin of the Tibetan Plateau. In this study, we built a 2 m resolution digital elevation model of the South Heli Shan Fault based on high‐resolution GeoEye‐1 stereo satellite imagery and then measured 302 vertical displacements along the fault, which increased the measurement density of previous field surveys by a factor of nearly 5. The cumulative displacements show an asymmetric distribution along the fault, comprising three major segments. An increasing trend from west to east indicates that the fault has likely propagated westward over its lifetime. The topographic relief of Heli Shan shows an asymmetry similar to the measured cumulative slip distribution, suggesting that the uplift of Heli Shan may result mainly from the long‐term activity of the South Heli Shan Fault. Furthermore, the cumulative displacements divide into discrete clusters along the fault, indicating that the fault has ruptured in several large earthquakes. By constraining the slip‐length distribution of each rupture, we found that the events do not support a characteristic recurrence model for the fault.