西秦岭北缘断裂带特征地震平均复发间隔的确定和地震危险性评价

时间相依的地震危险性概率评估方法是最近10a来逐渐发展起来的，是一种将已获得的定量地质资料运用于活动断裂中—长期地震潜势概率评估的方法，从而使得在缺乏历史记载或仪器记录资料，但已获得断层平均滑动速率、同震位错、古地震年代序列等资料的活动断裂段上评估未来的发震概率成为可能。在定量计算活动断裂未来地震危险性的过程中，作为输入参数之一的特征地震平均复发间隔是一个至关重要的参数，它的确定将直接影响到概率计算的结果。对研究断裂上已获得的历史地震资料(H)、地质资料(G)和古地震资料(P)，笔采用了时间可预报(T)和准周期(Q)两种模式分别计算其平均复发间隔，比单一的只假定一种复发模式计算更具有完善性和可靠性。在叙述该方法的同时，以西秦岭北缘断裂为例，详细阐述了该断裂上特征地震平均复发间隔的确定，并在此基础上对西秦岭北缘断裂未来地震潜势作了定量评估。

Determination of the Average Recurrence Intervals of Characteristic Earthquakes and Estimate of Earthquake Risk on Northern Xiqinling Faults

The time-dependent method of probabilistic estimates of seismic potential, developed in recent ten years, is one that uses quantitative geological data obtained to forecast middle-long term earthquakes on active faults, making feasible assessment of probablity of earthquake occurrence on active faults lacking historical or instrumental recordation, but possessing average fault slip-rates, co-seismic displacements, chronological sequence of paleoseismic events and so on. In the course of quantitative calculations of earthquake risk on active faults, average recurrence interval of characteristic earthquake as one of the imputed data is a key parameter which has an important influence on results. As for historical earthquake data (H), geological data (G) and paleoseismic data (P) on active faults, we introduce the Time-predictable Model (T) and Quasi-periodic Model (Q) to calculate the average recurrence intervals respectively, which is more perfect and credible than the method using only one recurrence model. Calculation of the average recurrence intervals on Northern Xiqinling Fault is used as an example to specify this approach, also, basing on its seismic potential on Northern Xiqinling Fault is given quantitatively.