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针对山西地区Pb震相难以准确识别的现状,本文首先根据地壳速度模型计算了能够记录到Pb震相的震中距范围.然后针对Pb作为初至、后续震相分别提出了相应的识别方法:当Pb作为初至震相时周期大于Pg,振幅小于Pg,波性特征与Pn相似,可使用理论到时与波形特征相结合的方法识别;当Pb作为后续震相时,振幅和周期都不稳定、存在突变点,综合使用理论到时、波形特征和离散小波变换三种方法进行识别.最后,依照上述方法识别、标定了56个地震事件中的236个Pb震相,计算得出山西地区下地壳P波的速度为6.73 km/s,康拉德面的埋藏深度为21 km.
Aiming at the current situation that it is difficult to accurately identify the Pb seismic phase in Shanxi Province, this paper first calculates the range of the epicenter distance from which the Pb seismic phase can be recorded according to the crustal velocity model.Secondly, a corresponding identification method is proposed for Pb as the first arrival and subsequent seismic phases respectively: When Pb is the first-onset phase, the period is greater than Pg, and the amplitude is less than Pg. The wave characteristics are similar to Pn, and can be identified by the combination of theoretical arrival time and waveform characteristics. When Pb is the subsequent seismic phase, both amplitude and period are unstable , The existence of mutation points, the theory of comprehensive use of the time, the waveform characteristics and discrete wavelet transform three ways to identify.Finally, according to the above method to identify, identify the 566 earthquakes in the 236 Pb phase, calculate the Shanxi region The crustal P-wave velocity is 6.73 km / s, and the Conrad surface burial depth is 21 km.