青藏高原东北缘主要断裂闭锁特征和滑动亏损研究

Locking Characteristics and Slip Deficits of the Main Faults in the Northeast Margin of Tibetan Plateau

利用1999—2015年GPS水平速度场,基于块体-位错模型,反演了青藏高原东北缘4条主要断裂(海原断裂,六盘山断裂,陇县—宝鸡断裂,西秦岭北缘断裂)的闭锁程度和滑动亏损速率的空间分布,并分析了各断裂的地震危险性。结果显示,六盘山断裂南段、陇县-宝鸡断裂北段、西秦岭北缘断裂东段闭锁程度最强,闭锁深度达到24km左右;西秦岭北缘断裂东段滑动亏损速率最大,平均值达到3mm/a;六盘山断裂南段、陇县—宝鸡断裂北段滑动亏损速率平均值达到1.9mm/a,稍弱于西秦岭北缘断裂东段;海原断裂闭锁程度和滑动亏损速率相对较小,闭锁程度和滑动亏损都仅分布在浅部。我们认为现阶段海原断裂的地震危险性相对较小,六盘山断裂南段、陇县—宝鸡北段、西秦岭北缘断裂东段地震危险性高于这些断裂的其他段落。这些结果对于青藏高原东北缘地震危险性判定和地震灾害评估具有参考意义。

By using horizontal data during 1999—2015 and based on the block-dislocation model,this paper inverted the spatial distribution of locking degree and slip deficit rate of four main faults,Haiyuan,Liupanshan,Longxian-Baoji and west Qingling faults in northeast margin of Tibetan plateau.Combining the inversion results,the earthquake potentials of the four faults was analyzed.The inversion results show that the locking degree of the southern segment of Liupanshan fault,the northern segment of Longxian—Baoji fault and the eastern segment of West Qingling are the strongest with blocking depth up to 24 km.The slip deficit rate of the eastern segment of the West Qingling fault is largest with average up to 3 mm/a.The southern segment of Liupanshan fault and the northern segment of Longxian—Baoji fault are slightly smaller than that of the northern segment of Longxian—Baoji fault with average up to 1.9 mm/a.Both the locking degree and slip deficit rate of Haiyuan fault are relatively small and distribute in shallow part.The analysis result suggests the earthquake risk of the southern segment of Liupanshan fault,the northern segment of Longxian—Baoji fault and the eastern segment of West Qingling fault are larger than other segments of these faults.