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1976年龙陵地区地震前后垂直形变的演变过程
THE EVOLUTION OF VERTICAL DEFORMATION IN LONGLING AREA BEFORE AND AFTER THE 1976 EARTHQUAKE
【摘要】 本文利用龙陵地区自1958年至1983年进行的一、二等水准测量结果,对该区地震前、地震时和地震后的地面垂直运动情况进行了分析,发现在地震发生前十多年震中区周围自澜沧江向西已出现了一缓慢的抬升趋势,累计值达46毫米,特别在团田至龙陵区段内变化尤为突出。重力测量结果也出现明显减小,二种手段所获得的前兆现象是一致的。地震后八年,由于地下物质发生了新的调整,形变逐渐趋于平稳,重力变化与垂直形变正好与震前相反,呈现整体下沉,留下了震后永久形变的痕迹。作者认为该区的地震形变周期已接近结束,附近地区所出现的新的变化是另一周期的开始。总结这次龙陵地震的垂直形变和重力变化结果,其变化模式如下:膨胀(上升)——突变(震时)——收缩(下沉)——新的膨胀(上升)。
【Abstract】 Based on the first or second order levelling measurements in Longling area in 1958-1983, an analysis has been made on the status of vertical ground movements before, during, and after the 1976 earthquake in the area. It has been found out that a gentle uplift (with a cumulative value of 46 mm) was occurred west of Lancangjiang River in the epicentral area ten years and more before the earthquake. The uplift, particularly, was much predominant along the segment from Tuantian to Longling.At the same time, an abvious decrement has also been found out in the gravitational measurements that were consistent with the levelling data.Eight years after the earthquake, the deformation gradually tended to be stabilized because of the readjustments of underground materials. The gravitational variation and vertical deformation were diametrically opposed to those before the event, featuring an integral depression and leaving marks of permanent deformation. The authors hold that, the seismic deformation cycle in the area is close to an end, and the newly-found variation in its vicinities is a start of another cycle.
- 【文献出处】 地震研究 ,Journal of Seismological Research , 编辑部邮箱 ,1987年06期
- 【被引频次】2
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