Lg-wave attenuation relationship and site response of stations in Zhejiang area
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摘要: 基于浙江省数字地震台网2007—2012年记录的台湾地区355次MS≥4.0地震的波谱比数据, 使用场地响应与路径衰减联合反演的方法, 对穿越台湾海峡特定路径的Lg波衰减关系及浙江地区36个测震台站的场地响应参数进行了计算. 计算中选取频率为1—7 Hz、 间隔为0.2 Hz, 计算得到了三分向(U--D, N--S, E--W)的衰减关系及场地响应参数. 三分向衰减参数关系为γUD(f)=0.0055f0.94, γNS(f)=0.0064f1.11和γEW(f)=0.0048f0.90. 浙江地区36个台站均获得了稳定的场地响应, 其中庆元台在高频端表现出较明显的放大效应, 其它台站在所研究的频率范围内各分向场地响应大致相当, 并未显示出明显的方向性特征. 最后对场地响应的异常部分进行了具体分析和验证, 表明本文计算结果正确可靠.Abstract: Based on the spectral ratio data, the Lg-wave attenuation relationship along a specific path across Taiwan Strait and the site response from 36 stations in Zhejiang area were calculated by using the joint inversion method of field response and the path attenuation. We used the data of 355 MS≥4.0 earthquakes during the period of 2007—2012, which were recorded by Zhejiang digi-tal seismic network in Taiwan region. During the calculation process, the data in the frequency range of 1—7 Hz were selected with the interval of 0.2 Hz. The attenuation relationships are γUD(f)=0.0055f0.94, γNS(f)=0.0064f1.11 and γEW(f)=0.0048f0.90 in U--D, N--S and E--W direction. The site response at high-frequency end of Qingyuan station showed an obvious amplification effect, meanwhile, the site response of the other 35 stations are nearly equal without obvious direction characteristic. Furthermore, the abnormal results were analyzed and verified, suggesting the results in this paper be correct and reliable.
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Keywords:
- Lg wave /
- site response /
- path attenuation /
- joint inversion /
- spectrum
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表 1 台站响应分类
Table 1 Stations sorted by site response
类别 台站名(台站代码) 台站场地响应幅值范围 1 宁海(NIH), 舟山(ZHS), 鄞县(YIX), 嵊泗(SHS) 1—2 2 乐清(YUQ), 永康(YOK), 余姚(YUY), 海盐(HAY), 嘉兴(JAX), 宁波(NIB), 泰顺(TSH), 温州(WEZ) 1—2, 少部分略超出2 3 珊溪(SX), 淳安(CHA), 峰源(FY), 景宁(JIN), 桐庐(TOL), 新安江(XAJ), 新昌(XIC), 新浦(XP), 苍南(CAN) 1—3 4 北仑(BEL), 包垟(BY), 长兴(CHX), 湖州(HUZ), 临安(LIA), 天台(TIT), 万阜(WF), 萧山(XSH), 云湖(YH) 基本为1—3, 少部分略超出3 5 杭州(HAZ), 黄坦(HT), 衢州(WXJ), 黄龙(HL) 1—4 6 仰山(YS), 庆元(QIY) 最高超出5 表 2 搬迁后的庆元台(QIU)记录到的8次台湾地区地震
Table 2 Eight earthquakes in Taiwan area recorded by the station QIU
序号 发震时间 北纬/° 东经/° 震源深度/km ML 年-月-日 时:分:秒 1 2014-03-16 04:04:36.5 22.23 121.36 13.2 5.2 2 2014-03-17 21:12:57.2 24.06 122.37 15.8 5.3 3 2014-03-19 20:19:27.0 24.05 122.27 16.2 5.6 4 2014-03-05 00:01:40.8 23.19 120.74 5.6 4.4 5 2014-03-29 23:56:54.2 24.36 122.19 29.4 4.3 6 2014-04-01 08:11:22.9 23.95 121.09 23.4 4.3 7 2014-04-02 00:09:41.3 24.08 121.32 71.6 4.4 8 2014-04-09 01:33:25.1 23.69 121.76 42.5 4.3 -
台湾气象局.2014. 地震活动汇整[EB/OL]. [2014-12-24]. http://www.cwb.gov.tw/V7/earthquake/rtd_eq.htm. Taiwan Weather Bureau.2014.Earthquake report[EB/OL]. [2014-12-24]. http://www.cwb.gov.tw/V7/earthquake/rtd_eq.htm.