VERTICAL CRUSTAL DEFORMATION AND SEISMIC RISK ANALYSIS IN CAPITAL AREA AND NORTHERN PART OF SHANXI DOWNFAULTED ZONE
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摘要: 根据首都圈地区及山西断陷带精密水准复测资料,分析了近十年来地壳垂直形变状态与特征。结果表明,研究区的东北区域表现为整体下降,下降速率约2~4mm/a;但"北升南降"的运动格局基本没有改变。太行山以西至山西断陷带的东侧地区为整体隆升,隆升速率最大近8mm/a。运动的时空分布从"南快北慢"整体上升的特征,逐步转变为"北升南降"的有升有降的特征。西区上述运动性质发生变化是以2001年为分界线,同时在延怀盆地及其附近区域形成了四象限分布的形变图像。但这一图像从规模和量级上都小于大同地震前的变形。山西断陷带北部的运动表现为断陷型的垂直运动,整体呈下降趋势,运动速率为4~6mm/a。上述特征表明监测区未来2~3年内发生6级以上地震的可能性不大。Abstract: the vertical crustal deformation in recent 10 years is analyzed with repeated leveling data observed in Capital area and northern part of Shanxi downfaulted zone. The results show that the northeast region of the area is descending entirely with a rate of 2~4mm/ya, but the state of "uplifting in north and descending in south" is not changed. The area from west of Taihangshan Mountain to east of Shanxi downfaulted zone is uplifting with a rate nearly 8mm/ya. The distribution has changed gradually from entirely uplifting with a speed "rapid in south and slow in north" to "uplifting in north and descending in south". The variation in west area is divided by the year of 2001, and a four-quadrant deformation pattern has formed in Yanhuai Basin and its surrounding area. The pattern is smaller than that of before Datong earthquake both in scale and magnitude. The movement in northern part of Shanxi downfaulted zone shows vertical downfaulted character with a rate of 4~6mm/ya. The characteristics above mentioned indicates that over 6 earthquakes might not occur in recent 2~3 years in the area.
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