摘要
借助弹性块体边界负位错模型,获取了北祁连 河西地区1971～2000年5个时段地壳垂直运动反映的 构造块体及其边界断层运动、变形参量及构造梯度场的时空演化图像,高应变能积累部位和锁定能量强度。研究 了与门源Ms6.4、景泰Ms6.2、永登Ms5.8、景泰Ms5.9、玉门Ms5.9以及2003年10月25日民乐 山丹Ms6.1等 强震孕育有关的背景性前兆特征,初步建立了该区强震地点判定的定量依据:①在较大范围强烈隆起区内及其边 缘、梯度场高值区内及其边缘,尤其是与构造走向较为一致、隆起量5mm/a以上或梯度值8×10-8/a以上能达到 方圆50～100km甚至更大的区域;②强位错(3mm/a以上)锁定区段及其附近,较强负位错应力降或负位错地震 矩(分别为5×103Pa/a和5×1016Nm/a左右甚至更高)区段及其附近;或者显著加强段及其附近,可能发生6级左 右或6级以上地震。对应的异常越突出、项数越多、位置越重合,发震危险性越大。
By studied negative dislocation model of boundaries of elastic blocks,the movement and deformation parameters of the Northern Qilian-Hexi block and its boundaries and time-space evolution patterns of the tectionics gradient field,places of accumulation of high strain energy and intensity of locked energy as shown in the vertical movement in five phases from 1971 to 2000 are obtained,so are the background precursory features related to the generation of the strong earthquakes: Menyuan %M%s6.4, Jingtai %M%s6.2, Minle-Shandan %M%s6.1,etc. The quantitative bases for determining the locations where strong earthquakes will take place is summaried preliminarily as ① larger strongly uplifting region and its margins, region of gradient field and its margings, especially those regions uplifting over 5 mm/a of apophysis or with gradient of 8×10+{-8}/a and their area are 50～100 km (even more) diameter and being consistent with tectonic direction; ②The segment with higher dislocation (over 3 mm/a) and its adjacency; the segment with higher stress drop or seismic moment of negative dislocation (around 5×10+3 Pa/a or 5×10+{16}Nm/a, even more)and its neighborhood,or obvious enhanced segment and its adjacency where the earthquakes about or more than 6 magnitude may take place. The more outstanding are the anomalies, the more are the items of anomaly and the more consistent are the positions, the more possible is the occurrence of earthquakes.
出处
《大地测量与地球动力学》
CSCD
北大核心
2005年第1期40-46,共7页
Journal of Geodesy and Geodynamics
基金
地震科学联合基金:"地壳运动的非震负位错模型反演与强震地点预测研究"
中国地震局"十五"重点项目子课题:"中国大 陆构造变形变化特征和重点地区应变积累状态研究"
关键词
北祁连
地点预测
隆起
地壳垂直运动
构造块体
地震矩
断层运动
与门
锁定
边缘
vertical crust movement, negative dislocation model of boundaries of elastic blocks, tectonic gradient field, study of earthquake examples, the Northern Qilian-Hexi area
