试论截直断裂与地震——以华北的3条北东向断裂为例

截直断裂是发育在大型的走滑或斜滑断裂带末端的分支断裂，断裂带长期反复活动，在其末端，因地壳应力消散或减弱，断裂走向发生急剧转折之后，在转折点附近产生了截直断裂，截直断裂的性状可以归纳为如下几点：（１）发育于接近主干断裂末端的转折点附近，其走向与主干断裂的总体走向一致，性状与主干断裂相似；（２）切割的地层或控制的沉积较的裂为新；（３）断裂的长度较小，断面较主干断裂为陡，（４）形成的时代为主干断裂发育

The Made-Straight Faults and Earthquake, Discussion over Three Northwest Strike Faults in North China

Made-straight faults are the secondary faults which developed at the ends of great strike-slip or oblique fault zones. After a slip fault developed for a long time, the stress at its ends died out and the strike of the fault changed rapidly, as a result the made-straight faults developed near the turning points. The Characteristics of the made-straight faults can be summerized up as follows: 1. They develop near the turning points closely to the ends of main faults ,go along the strike of the main faults. Their character are similar. 2. The strata cut by made-straight faults and sediment controled by them arc younger than that by the main faults. 3. They are shorter and steeper than the main faults. 4. They developed in or after the later stage of the main faults. 5. They are the more active sections of the faults. Slipping along the stike of the main faults. the made-straight faults cause great earthquakes if they are obstructed by other structures in front, otherwise cause moderate or small earthquakes.