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通过对1932年昌马地震(7.6级)震中区(昌马盆地—西水峡断陷谷地内)的大比例尺活断层填图(1:5万),获得了沿地震断层带分布的时代、规模不同的山脊及冲沟的水平断错数据。分析结果表明:水平断错量具明显的分级特点,全新世以来,最大一级水平位错量平均为39米,平均年滑动速率为4.1毫米/年。 依据古陡坎侵蚀斜面的主坡角与其年龄的相关统计公式,求得最近一次历史未记载的强地震事件发生在距今约1968年,它与1932年昌马地震的间隔时间为1911年,由这些资料粗略的求得昌马断裂的蠕滑速率为1.37毫米/年,占整个走滑量的31.8％。本文由上述资料求得昌马断裂带的强震(M≈7.6)重复周期约为2051年。
Through the large-scale active fault mapping (1: 50000) of the epicenter area of Changma earthquake (7.6 in the Changma basin to the Xishui gorge) in 1932, an epoch distributed along the fault zone of the earthquake was obtained, Different levels of ridge and gully level fault data. The results show that the horizontal faults have obvious grading features. Since the Holocene, the maximum level of horizontal dislocation averaged 39 meters and the average annual slip rate was 4.1 mm / year. According to the statistical formula of the main slope angle of the ecliptic slope of the ancient steep canyon and its age, the most recent unrecorded strong earthquake event was found in about 1968, with an interval of 1911 from the 1932 Changma earthquake, From these data, the creep slip of the Changma fault is roughly 1.37 mm / year, accounting for 31.8% of the total strike-slip. Based on the above data, this paper finds that the strong earthquake (M≈7.6) repetitive period in Changma fault zone is about 2051 years.