Research on the Magnitude and Recurrence Interval of Characterized Earthquakes with Magnitude ≥6.7 Along the Northwestern Portion of the Xianshuihe Fault Zone in Western Sichuan, China

Abstract

AbstractThe Xianshuihe fault in Sichuan Province, southwestern China, is one of the major left‐lateral strike‐slip faults that emanate from Tibet and play a key role in accommodation of India's penetration into Eurasia. In the northwestern portion of the Xianshuihe fault zone, sixteen earthquakes of M ≥6.5 occurred since 1700. The northwestern portion of the Xianshuihe fault zone can be divided into four segments based on field investigation of recent earthquake ruptures, studies on time‐space distribution and recurrence behaviors of historical ruptures, geometry and structure of fault zones, geophysical background, and recent seismicity. Each segment is a fault unit that has produced historical ruptures and is able to produce future ruptures independently. In this paper, for evaluating the magnitude distribution and recurrence interval of the characterized earthquakes along the northwestern portion of the Xianshuihe fault zone, we develop a moment‐balanced model by taking into account new geologic, seismologic and geodetic information, extending the previous analysis through a keener appreciation of the “stress shadow” and the influence of historical events. The result shows that all the recurrence intervals of single‐segment ruptures are about 100 to 200 years, and are much shorter than the recurrence intervals of cascade ruptures and entire fault rupture.