新疆乌恰6.8级地震的场地响应分析*

(1.中国科学技术大学 地球和空间科学学院,合肥 230026; 2.新疆维吾尔自治区地震局,乌鲁木齐 830011)

强震动记录; 衰减; 乌恰地震; Nakamura方法; 场址效应; 新疆

Analysis of the Site Response of the MS6.8 Wuqia,Xinjiang Earthquake
ZHANG Zhen-bin1,2,TANG Li-hua2

(1.School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)(2.Earthquake Administration of Xinjiang Uygur Autonomous Region,Urumqi 830011,Xinjiang,China)

records of strong motion; attenuation; Wuqia earthquake; Nakamura's technique; site response; Xinjiang

备注

利用2008年10月5日新疆乌恰6.8级地震时新疆强震动观测台记录的S波资料和脉动观测资料,采用Nakamura方法计算了这些强震观测台的场地响应。结果 表明:(1)地震记录前10 s的脉动场地响应明显大于测试脉动和地震记录S波的场地响应,是测试脉动和记录S波场地响应的3倍,而测试脉动场地响应和S波记录场地响应基本相符。(2)当记录台站的等效剪切波速小于250 m/s时,测试脉动场地响应值在2.5~5.0之间; 当等效剪切波速大于250 m/s时,测试脉动场地响应值在1.5~3.0之间。(3)当记录台站覆盖层为同一种类型时,台站测试脉动场地响应小于1。

Selecting the records of the seismic microtremor before the MS6.8 Wuqia earthquake on october 5,2008 and the S-wave data of the earthquake recorded by Xinjiang Strong Motion Network,we calculate the response of the strong-motion at these 26 stations through the Nakamura's technique.The results are as the following:(1)Ten seconds before the P-wave,the site amplification effects of the Earth pulse are 3 times of the effects of S-wave and the effects of the testing pulsation.Meanwhile,the site amplification effects of S-wave are constsitent with the ones of the testing pulsa.(2)When the equivalent shear-wave velocity of the recording stations is lower than 250 m/s,the site-response value of the test pulsation will be between 2.5 and 5.0.When the equivalent shear-wave velocity of the recording stations is higher than 250 m/s,the site-response value of the testing pulsation will be between 1.5 and 3.0.(3)When the overlayers under the recording station are of the same type,the site response value of the test pulsation will be lower than 1.