山西断裂带活动趋势与动态特征

The Movement of Trend and Dynamic Character in Shanxi Fault Zone

利用沿山西断裂带布设的GPS监测网的 6期复测资料 (1996～ 2 0 0 1) ,分析了山西断裂带水平运动的趋势及动态活动特征。结果表明 :(1)现阶段趋势性活动表现为北段向西运动 ,南段向东运动 ,整体呈现逆时针的差异活动性质 ;但趋势性活动强度并不高 ,断裂带从南到北在垂直方向上的趋势性差异运动分量为 3mm a左右 ;该带的南北向伸展运动量也只有 1mm a ,而且主要发生在断裂带的北段。 (2 )趋势性运动所反映主压应变场的方位角为 72°。 (3)每年间的活动性质并不完全相同甚至相反 ,并偏离趋势性活动 ,由此所推算出的应变场参数不能反映基本应力场的物理特性。 (4)高频运动 (每年的 )不但存在而且复杂 ,强度是趋势运动的数倍。 (5 )无论是长趋势性活动还是每年的活动都看不出区内任何一条断裂两侧存在明显的差异性运动(包括走滑运动 )。趋势性运动结果不仅验证了华北地区西界受力“南强北弱”的基本特征 ,而且一直持续到华北腹地。断裂两侧无明显的差异活动可能说明板内各块体之间的差异活动是在一定的空间范围内通过渐变来完成的 ,并不是以某一条断裂或狭小条带为界的突变过渡来实现的。动态活动明显存在则可能表明 :(1)在基本应力场的大环境下存在着应力扰动行为。 (2 )由于介质的物性存在着差异 。

The horizontal motion trend and character of dynamic action in Shanxi fault zone was analyzed based on the six stages of re-measuring data of GPS monitoring network in Shanxi fault zone (1996～2001). The result indicated as follows:(1) The trend of movement in nowdays turn up westward movement in northern part, eastward motion in southern part of the zone and the zone takes on anticlockwise movement,but the active intension is not obvious, it was to be seen that the differential movement component perpendicular to the fault zone from the south to the north is 3mm/a,and its stretch in SN direction is only 1mm/a and only occurs on the northern segment of the zone; (2)The trend movement shows azimuth of main-pressure strain field is 72°; (3)The character of yearly movement is not same, even is opposite or departs each other,so the parameter of strain field calculated from these results could not reflect the physical character of basic stress field; (4)Movement of the high frequency is complex and its intension is several times than the trend movement; (5)The obvious movement difference including strike slip in both side of the fault zone could be not seen from whether the moverment of long trend or the yearly movement.\;The result of movement not only prove the presume is true,it is that the basic character of force acted on western margin of North China was stronger in the south and weaker in the north, but also the action mode go on hinterland of North China all ways. Inconspicuous movement difference in both sides of a fault is explained as that the difference of movement between blocks is gradually formed within a certain spatial dimension, rather than depending on only any fault or a narrow zone. The obvious dynamic action perhaps shows one there is a little upset of stress in basic stress field. Secondly, regional stress and strain take on uneven or out of step change because of difference in properties of matter medium.Thirdly, feedback was brought by the changes in all kinds of external environment.