对1944年3月10日新源7 1/4级地震震中位置的讨论

Discussion on The Epicentral Position of Xinyuan Earthquake with Magnitude 7 1/4 on March 10,1944

1944年3月10日发生在我国北天山西段的7 1/4级地震的震中曾先后被定在北纬42°30′、东经82°30′和北纬44°、东经84°。1986年在新源县城南的卡克博河发现了一条长18km的地震形变带②。经对形变带滑坡体上树木生长年代和滑坡壁坡角研究后判定,该形变带应为1944年3月10日7 1/4级地震造成。在研究前人资料和增补新烈度点的前提下重新勾绘的等烈度线显示出卡克博河地震形变带与极震区几何中心相一致。本文在综合分析北天山地震带地震活动与不同方向活断层的关系中发现,沿卡克博河断裂中强以上地震有呈线型分布特征,结合发现古地震遗迹等因素,作者建议将1944年3月10日7 1/4级地震的震中定在新源以南(43.3°N、83.3°E),称为1944年3月10日新源7 1/4级地震。

The epicentral position of the Xinyuan earthquake with magnitude 71/4occurring on March 10,1944, was once believed in 42°30′N , 82°31′ E. Later, the position has been modified to be 44°N , 84° E. However, a seismic deformed belt with 18 Km in length along the Qiakbi River was discovered in the south of Xinyuan County in 1986. We judged that the deformed belt was formed during the earthquake of magnitude 71/4 on March 10. 1944, based on the comparison between the ages of the oldestand youngest trees shaped on slope block and the landslip we reappraised and portrayed the isoseismal lines of intensity after studying previous materials and appending new intensity information. From this new portrayed isoseisms we found that the seismic deformed belt almost showed no difference to the geometric centre of epicentral area. We synthesized all kinds of factors: the relations between the seismic zone and active faults of different directions, the linear distribution of moderate and strong earthquakes along the Qiakbi River fault and ancient earthquake vestige of two sites on the fault. Thus, we suggested that the epicentral position of this earthquake (M71/4 )should be fixed in the south of Xinyuan (43. 3°N, 83. 3°E)and call it the Xinyuan earthquake with magnitude 71/4occurring on March 10, 1944.