GPS测量所揭示的西秦岭北缘断裂带现今活动特征
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摘要
西秦岭北缘断裂带是甘肃省东南部重点地震监视区内一条主要活动断裂带。为了研究该断裂的现今活动特征,在断裂两侧布设了GPS监测网,从1996～1998年完成了3期观测。测量结果表明,断裂北、南两侧存在明显的差异运动,南侧向东运动的速率比北侧大38mm/a。在GPS网中,缩短的边基本上为东西方向,伸长的边基本上为北西-南东方向。本区的主压应力方向为近东西向。断裂带的东部(武山附近)左旋特征明显。测量结果还表明,1997～1998年与1996～1997年相比,位移速率约减小了一倍,而压应变增大了一倍以上,这表明本区的压应力场在增强,有可能正在孕育一个新的地震。
The fault zone along the north\|margin of West Qinling Mountain is a major active fault zone in the key seismic monitoring area in the southeastern part of Gansu Province. In order to study the current activity characteristics of this fault, GPS monitoring network has been arranged along both sides of the fault and 3 measurements have been made from 1996 to 1998. The result indicates that obvious differential movement exists along the north and south sides of the fault and the eastward movement on the south side is 3\^8mm/a larger than that on the north side. In the GPS network, the shortened side is generally in the trend of EW and the extended side is basically NW to SE. The principal compressive stress trend in this area is about EW and the sinistral motion is obvious in the eastern part of the fault (near Wushan Mountain). The measured results also indicate that the displacement rate has decreased by 50% and the compressive strain has increased by 100% as compared the data of 1997～1998 to that of 1996～1997, which shows that the compressive stress field in this region is intensifying and the next earthquake might be developing at present.
The fault zone along the north\|margin of West Qinling Mountain is a major active fault zone in the key seismic monitoring area in the southeastern part of Gansu Province. In order to study the current activity characteristics of this fault, GPS monitoring network has been arranged along both sides of the fault and 3 measurements have been made from 1996 to 1998. The result indicates that obvious differential movement exists along the north and south sides of the fault and the eastward movement on the south side is 3\^8mm/a larger than that on the north side. In the GPS network, the shortened side is generally in the trend of EW and the extended side is basically NW to SE. The principal compressive stress trend in this area is about EW and the sinistral motion is obvious in the eastern part of the fault (near Wushan Mountain). The measured results also indicate that the displacement rate has decreased by 50% and the compressive strain has increased by 100% as compared the data of 1997～1998 to that of 1996～1997, which shows that the compressive stress field in this region is intensifying and the next earthquake might be developing at present.
引文
康来迅、张新基、石雅琴 ,1998a ,西秦岭北缘活断层带断层气的特征 ,地壳形变与地震 ,18( 2 ) ,4 1～ 4 8。
康来讯、张必敖、张新基 ,1998b ,西秦岭北缘活断层带断层气的基本特征 ,中国地震 ,14 ( 4 ) ,85～ 91。
马杏垣、丁国瑜、高文学 ,1989,中国岩石圈动力学地图集 ,北京 :地震出版社 ,5 4。
康来讯、张必敖、张新基 ,1998b ,西秦岭北缘活断层带断层气的基本特征 ,中国地震 ,14 ( 4 ) ,85～ 91。
马杏垣、丁国瑜、高文学 ,1989,中国岩石圈动力学地图集 ,北京 :地震出版社 ,5 4。
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