2002年12月14日甘肃玉门5.9级地震的发震构造研究  

STUDY ON THE SEISMOGENIC STRUCTURE OF THE YUMEN, GANSU PROVINCE M_S 5.9 EARTHQUAKE OF DECEMBER 14, 2002

作　　者：何文贵[1] 郑文俊[1] 赵广堃 马尔曼 董治平 

机构地区：[1]中国地震局地震预测研究所兰州创新基地 [2]甘肃省地震局,兰州730000

出　　处：《地震地质》2004年第4期688-697,共10页Seismology and Geology

基　　金：地震科学联合基金(104073);国家自然科学基金(40372086)共同资助。

摘　　要：野外调查结果表明,2002年12月14日发生在甘肃省玉门地区的5.9级地震,其宏观震中和仪器震中都位于祁连山北缘断裂上。仪器震中为39.8°N,973°E;宏观震中为397°N,973°E。震中区烈度为Ⅷ度,极震区呈长椭圆形,长轴走向N65°W,长度为15km;短轴走向N25°E,长度为12km。本次地震的发震断层应为祁连山北缘断裂内的次级断裂——旱峡-大黄沟断裂,地震为该断裂最新活动的结果。On December 14, 2002, an earthquake of M S 5.9 occurred in Yumen, Gansu Province. Field investigation revealed that both the macroscopic and measured epicenters of this event, the coordinate of which are 39.8°N,97 3°E and 39.7°N,97 3°E, respectively, are located on the northern mar￣ginal fault of the Qilian Mountains. The epicentral intensity was determined to be Ⅶ. The epicentral area appears as an elongated ellipse with N65°W trending long axis of 15km long and N25 E trending short axis of 12km long. The earthquake took place in the Yumen area, which is located on the northern margin of the Qinghai Tibet Plateau and the western section of the Qilian Mountains. There are several Holocene active faults, of which the most famous ones are the Altun and the Changma faults. Historically, several large earthquakes occurred on these two faults, such as the Changma ( M S=7 6) earthquake of 1932 and the earthquake ( M S=5.5) occurred on the eastern section of the Altun fault in 1933. The Yumen earthquake is a moderate strong one, which didnt produce distinct surface rupture zone. The event was the result of the most recent movement on the secondary fault of the northern marginal fault zone of the Qilian Mountains, namely the Hanxia Dahuanggou Fault. The evidence is as follows: Field investigation shows that the macroscopic epicenter of this earthquake is located in the area involving the Hanxia Coal Mine of Yumen, Yuerhong Village of Subei County and Yaomoshan. The trend of the epicentral area is just consistent with the Hanxia Dahuanggou Fault. Focal mechanism solution shows that the nodal plane A appears as thrust fault trending to 147° with a relatively small dip angle of about 26°, in accord with the general strike of the Hanxia Dahuanggou Fault. The P axis is oriented in 277° direction having an elevation angle of 27°. This may indicate that this earthquake was the result of stress concentration due to the action of nearly SN trending horizontal compressive stress. Aftershocks of this event were very

关 键 词：玉门5.9级地震 发震构造 祁连山北缘断裂 地质特征 

分 类 号：P315.2[天文地球—地震学]