川滇地区若干活动断裂带整体的强地震复发特征研究

Study on Recurrence Behaviors of Strong Earthquakes for Several Entireties of Active Fault Zones in Sichuan-Yunnan Region

我们根据历史地震资料 ,采用统计学方法研究了川滇地区 7条活动断裂带整体的强地震复发特征。结果表明 ,这 7条断裂带的强地震复发表现出趋于随机的、随机的、以及丛集的行为 ,复发过程不具有良好的准周期性 ,也不存在强度 -时间或者时间 -强度的相依性。组成断裂带的强震破裂段落的数量越多 ,复发过程就越复杂。相对的地震活跃期与平静期交替出现。其中 ,活跃期内地震复发间隔分布的离散性较大 ,可用Weibull分布近似描述 ;而平静期的持续时间分布的离散性较小 ,可用正态等分布近似描述。不同相对活跃期的持续时间及强震的数量差别很大 ,导致相对活跃期并非准周期重现。因此 ,基于断裂带整体强震复发间隔分布的中长期危险性概率评估仍然面临一定的困难。

We use statistical methods to study the recurrence behavior of strong earthquake on entireties of 7 active fault zones of Sichuan-Yunnan region based on historical earthquake data. The result shows that recurrences of strong earthquakes of the 7 fault zones behave near-random, random and clustering characters. The recurrence processes never play a well quasi-periodic behavior, and exhibit neither strength-time nor time-strength dependence. The more strong earthquake rupture segments that form a fault zone is, the more complicated the recurrence process is. Relatively active periods and quiet periods occur alternatively. Within the active periods, recurrence interval distribution has relatively large discretion, and can be well-fitted by a Weibull distribution. While the duration's distribution of the quiet periods has relatively small discretion, and can be described approximately by some distributions as the normal and so on. Both the duration and the number of strong earthquakes for every active period are obviously different. These lead to the relatively active periods having never repeated quasi-periodically. Therefore, the probabilistic assessment of middle- and long-term seismic hazard based on the strong earthquake recurrence for entireties of active fault zones still faces some difficulty.