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一九八七年一月二十四日新疆乌什东北发生6.4级地震。震前国家地震局和新疆维吾尔自治区地震局有明确的中期预报意见,乌什地震台根据前兆资料变化提出了短、临预测意见. 该地震极震区在沙依拉姆山口一带。此处山体震酥、陡崖崩塌长达一公里多,河床中地裂缝纵横交错,喷沙冒水多处可见。震中烈度为八度,等震线长轴方向约北东50°。 这是一次主—余震型地震。无明显前震。余震按N(t)=195.5/t~(1.76)衰减,可分为前期和后期余震。t_0较大,为三天。余震时间分布符合lg△T=0.36N+0.648和lg△t=1.014lgt-0.30。余震空间分布范围的东西对角线方向与等震线长轴及构造线方向基本一致,余震深度多为5—15公里。震前乌什地震台的定点水准、压容应变,地倾斜及极震区附近的土层应力等前兆观测手段出现明显的中、短、临异常。 地震发生在沙依拉姆山前北东向断裂上,是该断裂在近南北向区域应力作用下形成的。
On January 24, 1987, an earthquake measuring 6.4 on the northeast of Wushi, Xinjiang. Before the earthquake, the State Seismological Bureau and the Xinjiang Uygur Autonomous Region Seismological Bureau had clear medium-term forecast opinions. The Wush Seismic Station proposed short-term and temporary forecast opinions based on the changes of precursor data, which was located in the Shayam Pass. Here mountain crisp, cliff collapse up to more than one kilometer, criss-cross the ground cracks in the riverbed, sand blasting can be seen everywhere. The epicenter intensity was octave, and the direction of the long axis of isoseismic line was about 50 ° north-easterly. This is a major-aftershock-type earthquake. No obvious foreshock. Aftershocks attenuate by N (t) = 195.5 / t ~ (1.76), which can be divided into pre-and post-aftershocks. t_0 is larger, for three days. Aftershock time distribution in line with lg △ T = 0.36N +0.648 and lg △ t = 1.014lgt-0.30. The distribution of aftershocks in the east-west diagonal direction is basically the same as the direction of the isoseismic long axis and the tectonic line, and the aftershock depth is mostly 5-15 km. Pre-earthquake Wushi seismic stations sentinel levels, compressive strain, tilt and earthquakes near the earthquakes and other precursory means of observation showed obvious medium, short and temporary anomalies. The earthquake occurred on the NE trending faults in the Shayamu Mountains, forming under the stress of the near north-south region.