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以南北地震带北部的青藏高原东北边缘与华北构造区过渡部位为例,通过建立地震构造模型,计算静态库仑破裂应力改变量(ΔCFS),研究了该区1561~1920年360年间5次M≥7级地震之间的触发过程.结果表明,在1561年罗山东麓71/4级地震之后,下一次地震无一例外地发生在前面地震产生的应力触发区(ΔCFS>0).在4条被触发的发震断裂中,有3条发震断裂的平均ΔCFS>0.2×105Pa,最大可达0.62×105Pa,超出目前普遍认为触发应力阀值(0.1×105Pa).根据断裂库仑破裂应力变化量(ΔCFS)和构造应力累计率(δτ),计算获得了下一次地震发生的提前量(ΔT),地震活动提前量最大可以达到160a.在一条重要活动构造带或地区上,一次地震发生对下一次地震的触发缩短了地震重复发生所需要的累积时间,使得地震可以提前发生,这一方面使得某一特定的发震断裂在时间尺度表现出准周期性,另一方面使得空间上不同发震断裂的地震活动表现出丛集发生的现象.此项研究有助于认识断裂间相互作用特点、揭示地震丛集发生规律以及预测未来地震危险区.
Taking the transitional parts between the northeastern margin of the Qinghai-Tibet Plateau and the North China tectonic zone in the northern part of the North-South Seismic Belt as an example, the change of static Coulomb failure stress (ΔCFS) was calculated by establishing the seismic structural model. 7 earthquake.The results show that the next earthquake occurred in the area of stress trigger (ΔCFS> 0) caused by the previous earthquake after the 71/4 Luodongdong footfall in 1561. Among the 4 Among the triggered seismogenic faults, the average ΔCFS of three seismogenic faults is 0.2 × 10 5 Pa and the maximum is 0.62 × 10 5 Pa, which is beyond the current consensus that the trigger stress threshold (0.1 × 10 5 Pa) (ΔCFS) and tectonic stress accumulation rate (δτ), the advance amount (ΔT) of the next earthquake occurrence can be calculated and the advancement of seismic activity can reach up to 160. In an important tectonic zone or area, an earthquake occurs to the next The triggering of an earthquake shortens the accumulation time required for repeated earthquakes so that earthquakes can occur ahead of time. On the one hand, a particular seismogenic fault shows quasi-periodicity on the time scale and on the other hand, Seismogenic fault seismic activity phenomenon of clustering occurs. This study contributes to understanding fault interaction, reveal the law of earthquake clusters occur and predict future earthquake risk zone.