【摘要】：2016年1月21日門源MS6.4級地震發(fā)生在祁連-海原斷裂帶冷龍嶺斷裂北側(cè).此次地震鄰近冷龍嶺斷裂發(fā)生,震中距祁連山北緣斷裂帶民樂-大馬營斷裂和皇城-雙塔斷裂較遠,地震破裂面近北西向,與兩條斷裂的走向呈一定角度相交.震源機制解顯示此次地震為逆沖型地震,與冷龍嶺斷裂逆-走滑運動性質(zhì)略有差異.在野外地質(zhì)填圖的基礎(chǔ)上,采用構(gòu)造地貌分析、探槽開挖和~(14)C定年技術(shù)等研究方法,揭示冷龍嶺斷裂全新世活動明顯,可能表現(xiàn)為特征滑動行為,地震震級為M_W7.3~7.5;斷裂傾角較陡,傾向北北東,構(gòu)造樣式上表現(xiàn)為花狀構(gòu)造;最新一次地震事件的形成時間晚于1815~1065a BP.冷龍嶺北側(cè)斷裂是冷龍嶺斷裂西北端一條伴生斷裂,受到冷龍嶺斷裂左旋剪切在端部持續(xù)的構(gòu)造推擠作用,相應(yīng)發(fā)生彎曲,產(chǎn)生向外的構(gòu)造旋轉(zhuǎn)作用,偏離優(yōu)勢破裂方位,活動性相應(yīng)減弱,在地表表現(xiàn)為一條晚第四紀變形不明顯的逆斷裂,與斷裂整體呈北東向微突出的弧形形態(tài)和晚第四紀以來沒有斷錯地表的地質(zhì)地貌跡象相協(xié)調(diào),但此類斷裂在深部仍可能發(fā)生破裂,產(chǎn)生中強地震.斷裂幾何學特征和運動性質(zhì)與震源機制解揭示的斷層節(jié)面2產(chǎn)狀和運動性質(zhì)以及余震和地震烈度的分布特征較為吻合.冷龍嶺北側(cè)斷裂作為門源M_S6.4級地震發(fā)震構(gòu)造較為恰當.冷龍嶺北側(cè)斷裂此次的逆沖運動也為冷龍嶺斷裂下一次的運動騰出空間.在冷龍嶺北側(cè)斷裂歷史演化過程中,冷龍嶺斷裂和冷龍嶺北側(cè)斷裂對局部地形地貌產(chǎn)生構(gòu)造抬升作用.
[Abstract]:The Mengyuan MS6.4 earthquake occurred on January 21, 2016, on the northern side of the Lenglongling fault in the Qilian Haiyuan fault zone. The earthquake occurred near the Lenglongling fault, and the epicenter was far from the Minle-Daimaying and Huangcheng-Shuangta faults in the northern margin of Qilian Mountains, and the seismic fracture surface was near the NW direction, which intersected with the strike of the two faults at a certain angle. The focal mechanism solution shows that the earthquake is a thrust-type earthquake, which is slightly different from that of the Lenglongling fault in the nature of anti-strike-slip movement. On the basis of field geological mapping, by using structural geomorphology analysis, trench excavation and ~ (14) C dating technique, it is revealed that the Holocene activity of Lenglongling fault is obvious, which may be characterized by sliding behavior. The magnitude of the earthquake is Mushi W7.3 and 7.5; The dip angle of the fault is steeper, inclining to the north, north and east, and the latest earthquake event occurred later than 1815 ~ 1065a BP.. The northern Lenglongling fault is an associated fault at the northwest end of the Lenglongling fault, which is subjected to the continuous tectonic pushing and squeezing at the end of the left lateral shear of the Lenglongling fault, resulting in a corresponding bending, resulting in outward tectonic rotation and deviation from the dominant fracture direction. The activity is weakened correspondingly, and it shows a reverse fault in late Quaternary, which is not obvious deformation in the late Quaternary, which is in harmony with the arc shape of the whole fault in the north east direction and the geological and geomorphologic sign of no fault surface since the late Quaternary. However, such faults may still be ruptured in the deep, resulting in moderate earthquakes. The geometries and motion properties of the faults are in good agreement with the occurrence and movement characteristics of the fault joint plane 2 and the distribution characteristics of aftershocks and seismic intensity revealed by the focal mechanism solution. The northern Lengling fault is a suitable seismogenic structure for the Mengyuan M_S6.4 earthquake. The thrust movement of the northern side of the Lenglongling fault also makes room for the next movement of the Lenglongling fault. During the historical evolution of the northern Lenglongling fault, the Lenglongling fault and the northern Lenglongling fault caused tectonic uplift to the local topography and geomorphology.
【作者單位】： 中國地震局地質(zhì)研究所活動構(gòu)造與火山重點實驗室;中國地震局地殼應(yīng)力研究所地殼動力學重點實驗室;中國地質(zhì)大學地球科學與資源學院;中國地震局地震預測研究所;中國地震臺網(wǎng)中心;
【基金】：地震行業(yè)科研專項項目(編號:201408023) 中國地震局地殼應(yīng)力研究所基本科研業(yè)務(wù)專項項目(編號:ZDJ2015-16)資助
【分類號】：P315.2

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1 劉百篪;袁道陽;何文貴;楊明;;冷龍嶺活斷裂的古地震特征與1540年甘肅中部強震[A];中國地震學會第七次學術(shù)大會論文摘要集[C];1998年

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