华北盆地Lg波衰减及台站场地响应特征

发布时间：2018-01-22 03:57

本文关键词： 场地响应衰减联合反演解的稳定性地震　出处：《地球科学》2016年12期 　论文类型：期刊论文

【摘要】：华北盆地是中国大陆地震活跃区之一,通过地震波衰减及场地响应参数研究该区构造介质属性及台基属性对地震预测预报、灾害评估具有重要意义.基于Lg波谱比的联合反演方法是获得地震波衰减参数及场地响应的有效方法,通过随机重采样方法可以检验解的稳定性.使用华北盆地68个台站记录的2004—2008年的149次地震,震级ML为1.7~5.3的震中距为100~600km,按信噪比大于2的标准挑选有效垂向记录1 000多条,地震射线较好地覆盖了华北盆地38°N~41°N、114°E~120°E区域.采用2.60~3.65km/s的速度窗截取Lg波形并转化为频谱,研究频率范围为1~7Hz,频率间隔0.2Hz.计算得到的地震波衰减品质因子Q(f)与频率f的关系可表示为Q(f)=125±4.4f~(0.86±0.03),研究区为低Q0(对应频率1Hz),高频率依赖性的构造活跃区.基岩台站对地震波没有表现出明显放大作用,黄土沉积台站低频端比高频端明显放大;场地响应波动较大台站其解的标准偏差也大,说明场地响应的不稳定性体现了台基属性的非稳定性特征.
[Abstract]:The North China Basin is one of the seismically active areas in the mainland of China. Seismic wave attenuation and site response parameters are used to study the seismic prediction and prediction by the attributes of the tectonic medium and the seismic platform. The joint inversion method based on LG spectrum ratio is an effective method to obtain attenuation parameters and site response of seismic wave. The stability of the solution can be tested by random resampling method. 149 earthquakes recorded from 2004 to 2008 were recorded from 68 stations in North China Basin. The epicentral distance with M _ L of 1.7N _ (5.3) is 100 ~ 600km. According to the criterion of signal-to-noise ratio (SNR) > 2, more than 1,000 effective vertical records are selected. The seismic rays well covered the 38 掳N ~ (41) ~ (41) 掳N ~ (-1) ~ (114) 掳E ~ (12) 掳E area of the North China Basin. The LG waveform was intercepted by a velocity window of 2.60 ~ 3.65 km / s and converted into the frequency spectrum. The frequency range is 1 ~ 7 Hz. The relationship between the attenuation quality factor (QF) and frequency f can be expressed as QF 125 卤4.4 fU 0.86 卤0.03). The study area is low Q _ 0 (corresponding frequency 1Hz ~ +, high frequency dependent tectonic active area). The bedrock station has no obvious amplification effect on seismic wave, and the low frequency end of loess depositional station is obviously enlarged than the high frequency end. The standard deviation of the solution is also large, which indicates that the instability of the site response reflects the instability of the base attribute.
【作者单位】：浙江省地震局;
【基金】：国家自然科学基金重大项目(No.41090291) 中国地震局星火计划项目(No.XH12023)
【分类号】：P315
【正文快照】： 华北盆地位于中国大陆北部,地处燕山以南,太行山以东,南以广饶-聊城断裂为界,东与渤海湾相接,郯庐断裂带穿过渤海湾构成其东界.在地质演化过程中,由于不均匀张裂和沉降,形成复杂的断层分布特征,地形地貌上隆凹相间,是典型的多次张裂盆地(黄金莉和赵大鹏,2005),新生代以来,研究

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