额尔齐斯活动断裂带

ERTIX ACTIVE FAULT ZONE

额尔齐斯活动断裂带由５条活动断裂构成，自东向西撒开，延伸约６５０ｋｍ，具右旋走滑逆冲性质。该断裂带自更新世晚期以来均有活动，现今垂直错动速率为６．２５ｍｍ／ａ，右族走滑速率为５ｍｍ／ａ，总滑动速率为８ｍｍ／ａ；自更新世晚期以来右施及垂直错动量均达２０～６０ｍ。１９９０年斋桑７．３级地震、１９３１年富蕴８级地震及更新世晚期的古地震使斋桑—乌伦古断裂、玛因鄂博断裂和额尔齐斯河断裂发生破裂。其中玛因鄂博断裂从全新世中期以来就发生过３次古地震，平均复现期为２８４３±９２ａ。通过玛因鄂博断裂和额尔齐斯断裂的详细研究后认为，断裂带未破裂地段是未来发生大地震的可能地段。

Ertix active fault zone,consisting of five active faults with an extension of about 650 km from east to west,owns characteristics of right-handed strike-slip thrusting. The fault zone has been active since the Pleistocene. Up to now the vertical displacement rate is 6.25 mm/a,right-handed strike-slip rate is 5 mm/a,and total strike-slip rate is 8 mm/a. Since the end of Pleistocene both right-handed and vertical displacement reach 20～60 m. The earthquake of 7.3 grade happened in Zhaisang in 1990,that of 8 grade in Fuyun in 1931 and that of the late Pleistocene led to the fracturing of Zhaisang-Ulungu fault,Mayin Ebo fault and Ertix River fault. Three-time earth-quakes had happened since the middle Holocene on Mayin Ebo fault,with an interval of 2 843±92 a. A detailed study of Mayin Ebo fault and Ertix fault suggests the non-fractured sections of the fault zone be the possible area where large earthquakes may happen.