Abstract: In this paper from the data of field investigation,a surface rupture zone of the Ge-ngma earthquake in Yunnan Province is studied. Meanwhile,a dislocation model of the tension-torsion fault type is suggested from the data on fault dislocation. It is shown that the seismogenic structure for the Gengma earthquake is dominated by right-lateral horizontal offset with horizontal extension. The maximum dislocation is 1.6 meter and the maximum strike slip is 0.96 meter. The preferred direction of sliding vector is NW-SE 55°at a dip angle about 30—40°. The result of stress analysis suggests that the preferred direction of principal compressive stress is N5—10° E at an elevation angle about 40—60° in the earthquake area.

Key words: Gengma earthquake, Rupture zone, Dislocation, Sliding vector, Stress

摘要： 根据野外考察的实际资料,本文介绍了耿马7.2级地震地表破裂带的展布,结构要素及组合、位移分布等情况。同时依据位错资料对破裂带的应力活动及断裂两盘的运动状态进行了初步分析。认为本次地震发震构造以右旋走滑为主兼具张性,主压应力优势方位为N5°—10°E。断层两盘相对运动的总体方向为N55°W左右,断层运动的滑移角在30°—40°之间。

关键词: 耿马地震, 破裂带, 位错, 滑动矢量, 应力