Türkiye is located in a seismically active region,where the Anatolian,African,and Arabian tectonic plates converge.High seismic hazards cause the region to be struck repeatedly by major earthquakes.On February 06...Türkiye is located in a seismically active region,where the Anatolian,African,and Arabian tectonic plates converge.High seismic hazards cause the region to be struck repeatedly by major earthquakes.On February 06,2023,a devastating M_(W)7.7 earthquake struck Türkiye at 01:17 am local time(01:17 UTC).In this regard,near and far-field ground motion data within the distance of 120 km are compiled and later characterized to identify the key ground motion intensity measures.Additionally,the vertical components of ground motions were examined to capture the complete three-dimensional nature of the seismic event.Moreover,the effect of Pulse-Like(PL)and Non-Pulse-Like(NPL)ground motion on a representative RC frame structure built as per the Türkiye code was investigated.The results indicate that PL behavior was observed in both horizontal and vertical components of ground motions and PL behavior were noted both near the epicenter and at higher distances from the epicenter.Moreover,the ratio of the peak vertical acceleration to peak horizontal acceleration at certain stations was found to be close to 1.Finally,the non-linear time history analysis of the representative reinforced concrete frame structure for ground motions recorded at stations located equidistant from the epicenter,indicated that PL ground motions led to more significant damage compared to NPL ground motions.展开更多
In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(...In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.展开更多
微动H/V谱比,即地表记录的不同频率地震背景噪声的水平分量与垂直分量的比值.在工程地震领域,通常用V表示微动记录的垂直分量,用H表示微动记录的水平分量,测得作为频率函数的H/V谱比曲线后,依据一定的关系(通常是经验的),建立H/V谱比曲...微动H/V谱比,即地表记录的不同频率地震背景噪声的水平分量与垂直分量的比值.在工程地震领域,通常用V表示微动记录的垂直分量,用H表示微动记录的水平分量,测得作为频率函数的H/V谱比曲线后,依据一定的关系(通常是经验的),建立H/V谱比曲线的峰值与地层结构基阶共振频率之间的关系,从而估计沉积层厚度或场地放大因子,有时也称为HVSR(Horizontal-to-Vertical Spectral Ratio)或QTS(Quasi Transfer Spectrum)方法.由于微动中波型成分的物理来源模糊不清,其主导能量究竟是Rayleigh波、S波或者其它波型成分存在争议,因此,虽然在工程地震领域获得了广泛应用,微动H/V谱比法仍然缺乏严格的理论解释.这导致该方法趋于两个方向发展:一是从地震记录中,识别出Rayleigh波能量,计算Rayleigh波的ZH幅度比,又称Rayleigh波椭率(ellipticity).之所以称为Rayleigh波ZH幅度比,是因为在地震层析成像领域,V常用来表示Rayleigh波水平分量的特征函数,多用Z表示Rayleigh波的垂直分量.作为独立变量,Rayleigh波ZH幅度比对浅层速度结构更为敏感,在区域尺度地震层析成像领域获得广泛应用,用于弥补单独相(群)速度对浅层结构,尤其是沉积层结构约束不够的缺点.这种方法意味着H/V谱比曲线中的主要能量是Rayleigh波,除了在区域尺度与Rayleigh波的频散和(或)接收函数联合反演地球结构之外,在工程物探领域,也利用Rayleigh波椭率反演近地表S波速度结构.基于H/V谱比曲线的峰值推断场地响应的理论假设是SH波占据微动的主导能量,这与微动观测记录通常由Rayleigh波能量占据主导地位的情况不符,因此H/V谱比法的另一个研究方向是发展不同的背景噪声源模型,考虑可能贡献的背景噪声能量,解释H/V谱比曲线.这样就避免了微动记录的主导成分是面波还是体波的争论,发展更适合或接近实际记录的微动模型解释H/V谱比曲线,该方向的发展是伴随地震干涉理论的发展而逐步发展起来的.我们曾经对区域尺度的(地震事件或背景噪声)Rayleigh波ZH幅度比的研究和应用进行了评述.本文主要评述微动H/V谱比法在工程地震领域和近地表S波速度结构反演中的应用及相应的理论解释.包括基于SH波共振频率解释的微动H/V谱比法估计场地特征,基于Rayleigh波占据微动主导能量的Rayleigh波椭率在反演近地表速度结构中的应用,以及为解释实际微动H/V谱比曲线而发展的背景噪声源模型.展开更多
In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is importa...In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is important to know detailed ground characteristics to do damage prediction on a fine scale. Using GIS is the best way to communicate this planar disaster prevention information to the general public. Yokohama City is the second largest city in Japan and developed as part of the capital region of Metropolitan Tokyo. Recently, the population of this city has reached about 3,000,000, and economic and cultural facilities, social infrastructure, and residential complexes are concentrated in this city. The capital region, including Yokohama City, was attacked by the 1923 Great Kanto Earthquake (M7.9) and Yokohama City was devastated by this earthquake. From the research so far, it is known that the H/V spectrum obtained from microtremor observation has a good correlation with the ground characteristics. The authors have been conducting high-density tremor observations that have been ongoing since the 1990s, mainly in Kanagawa Prefecture, Japan. Here, we have organized the predominant periods obtained from the observation results for Yokohama City. The entirety of Yokohama City was divided into 250 m × 250 m meshes and their centers were used as microtremor observation sites. Excluding sites that could not be used due to geographical conditions, observations were made at approximately 5700 sites. So, we compared the data obtained separately, such as the period, terrain classification, and amplification characteristics. The distribution maps of predominant periods in Yokohama City show that the city contains a lot of artificially transformed land, and consequently, the distribution of predominant periods is not uniform. However, it can be seen that the periods become gradually longer, moving from the higher elevation eastern part toward the lower elevation western part. Investigation of the site amplification factors and detailed topographical classifications indicates a clear correlation with the predominant period distribution.展开更多
文摘Türkiye is located in a seismically active region,where the Anatolian,African,and Arabian tectonic plates converge.High seismic hazards cause the region to be struck repeatedly by major earthquakes.On February 06,2023,a devastating M_(W)7.7 earthquake struck Türkiye at 01:17 am local time(01:17 UTC).In this regard,near and far-field ground motion data within the distance of 120 km are compiled and later characterized to identify the key ground motion intensity measures.Additionally,the vertical components of ground motions were examined to capture the complete three-dimensional nature of the seismic event.Moreover,the effect of Pulse-Like(PL)and Non-Pulse-Like(NPL)ground motion on a representative RC frame structure built as per the Türkiye code was investigated.The results indicate that PL behavior was observed in both horizontal and vertical components of ground motions and PL behavior were noted both near the epicenter and at higher distances from the epicenter.Moreover,the ratio of the peak vertical acceleration to peak horizontal acceleration at certain stations was found to be close to 1.Finally,the non-linear time history analysis of the representative reinforced concrete frame structure for ground motions recorded at stations located equidistant from the epicenter,indicated that PL ground motions led to more significant damage compared to NPL ground motions.
基金Project(2011CB013605)supported by the National Basic Research Development Program of China(973 Program)Projects(51178071,51008041)supported by the National Natural Science Foundation of ChinaProject(NCET-12-0751)supported by the New Century Excellent Talents Program in University of Ministry of Education of China
文摘In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.
文摘微动H/V谱比,即地表记录的不同频率地震背景噪声的水平分量与垂直分量的比值.在工程地震领域,通常用V表示微动记录的垂直分量,用H表示微动记录的水平分量,测得作为频率函数的H/V谱比曲线后,依据一定的关系(通常是经验的),建立H/V谱比曲线的峰值与地层结构基阶共振频率之间的关系,从而估计沉积层厚度或场地放大因子,有时也称为HVSR(Horizontal-to-Vertical Spectral Ratio)或QTS(Quasi Transfer Spectrum)方法.由于微动中波型成分的物理来源模糊不清,其主导能量究竟是Rayleigh波、S波或者其它波型成分存在争议,因此,虽然在工程地震领域获得了广泛应用,微动H/V谱比法仍然缺乏严格的理论解释.这导致该方法趋于两个方向发展:一是从地震记录中,识别出Rayleigh波能量,计算Rayleigh波的ZH幅度比,又称Rayleigh波椭率(ellipticity).之所以称为Rayleigh波ZH幅度比,是因为在地震层析成像领域,V常用来表示Rayleigh波水平分量的特征函数,多用Z表示Rayleigh波的垂直分量.作为独立变量,Rayleigh波ZH幅度比对浅层速度结构更为敏感,在区域尺度地震层析成像领域获得广泛应用,用于弥补单独相(群)速度对浅层结构,尤其是沉积层结构约束不够的缺点.这种方法意味着H/V谱比曲线中的主要能量是Rayleigh波,除了在区域尺度与Rayleigh波的频散和(或)接收函数联合反演地球结构之外,在工程物探领域,也利用Rayleigh波椭率反演近地表S波速度结构.基于H/V谱比曲线的峰值推断场地响应的理论假设是SH波占据微动的主导能量,这与微动观测记录通常由Rayleigh波能量占据主导地位的情况不符,因此H/V谱比法的另一个研究方向是发展不同的背景噪声源模型,考虑可能贡献的背景噪声能量,解释H/V谱比曲线.这样就避免了微动记录的主导成分是面波还是体波的争论,发展更适合或接近实际记录的微动模型解释H/V谱比曲线,该方向的发展是伴随地震干涉理论的发展而逐步发展起来的.我们曾经对区域尺度的(地震事件或背景噪声)Rayleigh波ZH幅度比的研究和应用进行了评述.本文主要评述微动H/V谱比法在工程地震领域和近地表S波速度结构反演中的应用及相应的理论解释.包括基于SH波共振频率解释的微动H/V谱比法估计场地特征,基于Rayleigh波占据微动主导能量的Rayleigh波椭率在反演近地表速度结构中的应用,以及为解释实际微动H/V谱比曲线而发展的背景噪声源模型.
文摘In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is important to know detailed ground characteristics to do damage prediction on a fine scale. Using GIS is the best way to communicate this planar disaster prevention information to the general public. Yokohama City is the second largest city in Japan and developed as part of the capital region of Metropolitan Tokyo. Recently, the population of this city has reached about 3,000,000, and economic and cultural facilities, social infrastructure, and residential complexes are concentrated in this city. The capital region, including Yokohama City, was attacked by the 1923 Great Kanto Earthquake (M7.9) and Yokohama City was devastated by this earthquake. From the research so far, it is known that the H/V spectrum obtained from microtremor observation has a good correlation with the ground characteristics. The authors have been conducting high-density tremor observations that have been ongoing since the 1990s, mainly in Kanagawa Prefecture, Japan. Here, we have organized the predominant periods obtained from the observation results for Yokohama City. The entirety of Yokohama City was divided into 250 m × 250 m meshes and their centers were used as microtremor observation sites. Excluding sites that could not be used due to geographical conditions, observations were made at approximately 5700 sites. So, we compared the data obtained separately, such as the period, terrain classification, and amplification characteristics. The distribution maps of predominant periods in Yokohama City show that the city contains a lot of artificially transformed land, and consequently, the distribution of predominant periods is not uniform. However, it can be seen that the periods become gradually longer, moving from the higher elevation eastern part toward the lower elevation western part. Investigation of the site amplification factors and detailed topographical classifications indicates a clear correlation with the predominant period distribution.
