地震背景噪声HVSR法探测雄安地区场地响应和浅层沉积结构  

USING SEISMIC AMBIENT NOISE HORIZONTAL-TO-VERTICAL SPECTRAL RATIO(HVSR)METHOD TO DETECT SITE RESPONSE AND SHALLOW SEDIMENTARY STRUCTURE IN XIONG’AN AREA

作　　者：阮明明 刘巧霞[2] 段永红[2] 王帅军[2] 郑成龙[2] 王亮 RUAN Ming-ming;LIU Qiao-xia;DUAN Yong-hong;WANG Shuai-jun;ZHENG Cheng-long;WANG Liang(Key Laboratory of Intelligent Detection and Equipment for Underground Space of Beijing-Tianjin-Hebei Urban Agglomeration,Ministry of Natural Resources,Shijiazhuang 050031,China;Geophysical Exploration Center of China Earthquake Administration,Zhengzhou 450002,China)

机构地区：[1]自然资源部京津冀城市群地下空间智能探测与装备重点实验室,石家庄050031 [2]中国地震局地球物理勘探中心,郑州450002

出　　处：《地震地质》2024年第5期1106-1122,共17页Seismology and Geology

基　　金：自然资源部京津冀城市群地下空间智能探测与装备重点实验室开放基金(ZB2022002)。

摘　　要：雄安新区建设是国家战略和千年大计,探查与地震灾害密切相关的沉积结构和地震场地响应特征,可为雄安地区的城市抗震设防提供重要依据。但该地区相对缺少与场地条件相关的研究,一些浅部探察结果由于资料覆盖有限,精度不高。文中利用台间距为1km的短周期密集台阵,基于HVSR法处理台阵背景噪声,结果表明:区域内大部分地区场地的放大系数<5,场地放大作用不显著;场地共振频率和沉积层埋深具有明显的分区特征,西部场地共振频率主要为0.8~1.2Hz,沉积厚度较薄,范围为100~160m。中西部场地共振频率主要为0.5~0.8Hz,沉积层厚度较厚,范围为160~210m;三维沉积层模型与钻孔资料、浅层电阻率法的地质解释图基本吻合,沉积层的起伏特征与断裂带分布、地质构造单元均有较好的对应关系,结果表明容西断裂、容东断裂、牛西断裂、牛东断裂、徐水-大城断裂作为雄安地区次级地质构造单元边界,影响了近地表的沉积层结构。文中通过HVSR法得到了雄安地区的场地参数,如沉积层共振频率、场地放大系数,以及高精度的近地表三维沉积层模型。上述结果可为雄安地区今后的地震小区划和抗震设防提供重要参考。The construction of the Xiong’an New Area is a national strategy and a long-term plan outlined by the Chinese government.To support the urban planning and development of this area,many scholars have conducted a series of geophysical surveys aimed at understanding the detailed subsurface structure.The Horizontal-to-Vertical Spectral Ratio(HVSR)method,first introduced by Nakamura,has recently gained widespread use for investigating shallow subsurface structures,site response,and microzonation.In this study,we utilized a large seismic array with an interstation distance ranging from 500 to 1000 meters,deployed across the Xiong’an New Area.The array consisted of over 900 short-period seismographs,covering most of the area.Using ambient-noise recordings,we removed nonrandom transient signals from the waveform data with a short-term-average over long-term-average detector automatic picking algorithm,and applied the Konno-Ohmachi algorithm to smooth the HVSR curves.For each site,we analyzed the amplitude of the peak value of the HVSR curve(A)and the corresponding frequency(f0).Both parameters were further elaborated through the creation of contour maps using the Kriging interpolation method.Additionally,the peak frequencies from the HVSR curves were used to calculate the sedimentary thickness,based on an average shear-wave velocity and the frequency-depth formula.The frequency map shows that the peak frequencies range between 0.6 and 1.1Hz,with an overall peak frequency of about 0.7 to 1.0Hz.The lowest frequencies were found predominantly in the vast eastern area of the study region,corresponding to geological features such as the Niubei Slope,Niutuozhen High,and Baxian Sag.According to the frequency-depth formula,a lower peak frequency indicates greater sediment depth.The variation in peak frequencies across stations highlights changes in the bedrock interface,which correspond to fault structures depicted on the geological map.Furthermore,high-amplitude areas were mainly located between the Rongxi fault and Rongdon

关 键 词：雄安地区 HVSR法 浅层沉积层结构 场地特征 

分 类 号：P315.2[天文地球—地震学] P315.9[天文地球—固体地球物理学]