次声监测方法在灾害监测方面得到了越来越广泛的应用,特别是在地震监测领域。大震来临之前1~10 d,通常都会接收到次声波异常信号,这种异常信号是由于孕震末期地质体运动引起地表波动而产生的。本文以2004 年苏门答腊8.7 级大地震为例,观测研究其震前接收到的次声波异常信号,并利用有限元数值模拟方法模拟了次声波异常信号的产生。分析结果表明,苏门答腊大地震发生之前的孕育末期,地质体的动力学行为引起了次声波,次声波的能量主要集中在10-3 Hz 量级上,研究次声波的异常信号可能为地震预测提供一条有价值的途径。
Infrasound monitoring method has been widely applied in disaster monitoring, especially in earthquake monitoring. One to 10 days before an earthquake, abnormal infrasound waves can usually be received. However, the formation mechanism of the abnormality remains unclear. This paper takes the Sumatra earthquake in 2004 as an example to study the abnormal infrasound signal received before the earthquake and simulate production of the infrasound through finite element modeling. The interaction between atmosphere and deformation of the earth surface caused by dynamic behavior of geologic bodies in the final stage of earthquake incubation caused the observable infrasound. Infrasound was obtained by numerical simulations. Satisfactory agreement between the observed and the simulated infrasound suggests that the proposed model is reasonable. The results show that the atmosphere before the earthquake may have low-frequency sound, and its frequency was focused on the 10-3 Hz order of magnitude. There was a good correlation between earthquake and abnormal infrasound signals. The abnormal infrasound signal may be a valuable way for earthquake prediction.
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