图2  永登5.8级地震区域地质构造及历史地震分布

断裂名称：①冷龙岭断裂；②老虎山-毛毛山断裂；③海原断裂；④天景山断裂；

          ⑤庄浪河断裂；⑥兴隆山-马衔山断裂；⑦拉脊山北缘断裂；

          ⑧西秦岭北缘断裂；⑨通渭断裂

Fig.2  Sketch of geological structure and distribution of historical

       earthquakes around the epicentral area of the 5.8 Yongdeng earthquake