共查询到20条相似文献，搜索用时 640 毫秒
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2018年2月12日河北省廊坊市永清县发生4.3级地震,震中位于廊固凹陷内的河西务断裂附近,国家强震动台网中心获取74组强震动记录,本文对触发台站进行场地分类,结果显示大部分为Ⅰ类场地(51.35%),其次为Ⅱ类场地(35.14%)和Ⅲ类场地(13.51%)。根据5个典型台站加速度时程记录及反应谱分析本次地震强震动特征,并对各台站峰值加速度反应谱与方位角和震中距的关系进行分析。采用克里格插值方法绘制地震仪器烈度分布图,由于台站分布不均,导致极震区附近烈度影响场计算缺值现象,本文通过拟合本次地震强震动记录得到该地区地震动衰减关系,在空白区域建立空间随机假设台站进行补点插值,解决了计算缺值问题,为缺少台站记录的震区提供准确快速制作烈度分布图的思路,为震害调查和地震应急救援提供重要依据。 相似文献
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以2016年2月6日我国台湾高雄MS6.8地震中烈度仪观测网的实际记录为研究对象,通过对烈度仪台站的震相捡拾结果精度、峰值地震动衰减关系适用性、预警震级计算结果准确性等3方面的对比分析,研究了烈度仪用于地震预警时的优势和可靠性,并讨论了可能存在的问题和风险.研究结果表明:对于震中附近具有较高信噪比的烈度仪台站,采用现有震相捡拾方法即可获得较准确的震相到时信息;现有的地震动衰减关系并不完全适用于烈度仪台网,直接应用这些关系式时存在一定风险;基于密集布设的烈度仪观测台网,在较短时间即可获取大量信息,采用已有预警震级估算方法的计算结果有较高的准确性. 相似文献
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Housner谱烈度及修正谱烈度作为基于加速度记录时程直接得到的地震动强度参数,与建筑结构破坏及地震宏观烈度存在较高的相关性,是可靠的地震仪器烈度物理参数指标。然而,相对于地面加速度峰值、地面速度峰值等地震动峰值参数,三分量加速度记录对应的谱烈度计算过程较为复杂,耗时相对较长,影响了利用谱烈度确定地震仪器烈度的时效性。基于对强震动加速度记录的统计分析,本文提出了谱烈度的快速近似算法,仅计算4个方向上的谱烈度值,采用其中3点作圆即可获得水平面内谱烈度迹线的近似最大值,使计算速度提高了45倍,且保持了谱烈度作为地震仪器烈度物理指标的精度。利用在汶川MS 8.0地震等386次MS > 3.0地震中获取的2701组强震动加速度记录,经可靠性检验,结果表明所提出的Housner谱烈度快速近似算法的计算误差在±4.5%以内,可以同时满足地震仪器烈度速报的可靠性和时效性需求。 相似文献
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2013年7月22日甘肃省定西市岷县漳县交界发生6.6级地震,国家强震动台网在甘肃、四川和陕西的64台强震仪触发并获得了主震加速度记录。本文对强震动记录进行了常规处理,统计了强震动记录数量随震中距的分布,绘制了空间地震动加速度等值线图;通过观测数据与霍俊荣和意大利新一代地震动衰减公式对比,分析了峰值加速度(PGA)及谱加速度衰减关系,发现此次地震观测数值远低于常用地震动预测值;利用渭河盆地的远场记录验证了远场地震动卓越周期变大的特点以及场地对记录的影响;参考岷县地区地质特点并通过分析宏观烈度及地震动的谱烈度,初步确定了地震震害与烈度的相关性。 相似文献
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2017年6月3日内蒙古阿拉善左旗发生5.0级地震,位于甘肃天祝-古浪一带的"西部烈度衰减台阵"得到充分触发,甘肃强震动台网的50台强震仪获得了主震加速度记录。本文首先对150条强震动记录进行常规处理,计算出近场强震动记录的加速度峰值随震中距的分布情况;根据4个典型台站的加速度时程记录及其加速度反应谱,分析本次地震的基本特征;然后将实际观测数据与意大利新一代地震动衰减公式对比,分析峰值加速度（PGA）及谱加速度衰减关系;最后结合已有的工程场地地质资料,采用H/V谱比法对4个不同类别的典型台站进行分析,发现该方法能很好地反映实际台站场地的反应特征。 相似文献
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Ali A. Nowroozi 《Pure and Applied Geophysics》2010,167(12):1459-1474
The active faults near Tehran are capable of producing Mw magnitudes of 6.62?C7.23; at epicentral distances of 25?km from the active faults, and Mw?=?7.23, the peak ground horizontal acceleration, PGH, is between 386 and 730?cm/s2 and peak ground vertical acceleration, PGV, is between 192 and 261?cm/s2; the historic earthquake of the fourth century BC, Mw?=?7.16 produced the highest estimated PGH acceleration in Tehran, between 254 and 479?cm/s2 and PGV acceleration between 127 and 173?cm/s2. Earthquakes from 1909 to 2008, within 300?km from Tehran, are used for calculation of magnitude frequency relation, and results are applied to estimate PGH and PGV accelerations as a function of magnitudes for a set of fixed epicentral distance and site conditions; also as a function of epicentral distances for a set of fixed magnitudes and site conditions. Poisson??s distribution is used for probability calculation of PGH and PGV accelerations for several exposure times, site conditions and epicentral distances; accelerations with very high probability, near 1, are presented. At an epicentral distance of 10?km and exposure time of 450?years, in the northern part of Tehran, close to Mosha and the Northern Tehran faults, PGH acceleration is 800?C420?cm/s2 and PGV is 400?C220?cm/s2 with high probability. At an epicentral distance of 25?km and 1,000?years exposure time, PGH is 610?C320?cm/s2 and PGV is 310?C160?cm/s2 with high probability, where larger values are for soft soil and smaller values are for hard rock. 相似文献
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利用《中国地震动参数区划图》采用的地震动参数衰减关系,以及《中国地震动参数区划图》中地震动峰值加速度和地震动加速度反应谱特征周期反推不同设防烈度和设计地震分组对应的震级和震中距,再根据《建筑抗震设计规范》中各设防水准的峰值加速度确定对应的震级和震中距,进而根据地震动强度包线参数与震级和震中距关系计算地震动强度包线参数的取值,为基于强度包线函数生成人工地震动提供参考,并讨论强度包线参数的取值规律：(1)随着设防烈度的提高,加速度时程曲线上升段持续时间t1和平稳段持续时间ts减小,下降段衰减指数c增大;(2)随着地震水准和设计地震分组的提高,加速度时程曲线上升段持续时间t1和平稳段持续时间ts增加,下降段衰减指数c减小;(3)在生成人工地震动时,除考虑峰值加速度和设计地震分组影响外,还需要考虑设防烈度影响。 相似文献
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烈度计台与测震台的布设环境、仪器类型不同,所测定的震级值存在一定差异。收集2017-2019年川滇地区301个烈度计台站记录的46次ML 3.0以上地震,进行震级校正。统计烈度计实测震级值与测震台网平均震级值的偏差,对原量规函数进行修正,进而做台站校正。综合修正后,利用量规函数和台站校正值重新计算烈度计震级,结果表明：在震中100 km范围内,烈度计测定震级偏差平均值由校正前的0.145降低至0.033,标准差由0.382降低至0.295,离散度减小;校正后的烈度计震级结果较优,说明本研究获得的量规函数和台站校正值更加适用于川滇地区烈度计台站的震级计算。 相似文献
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A. Joshi 《Journal of Seismology》2001,5(4):499-518
Garhwal Himalaya has been rocked by two major earthquakes in the span of just eight years, viz. Uttarkashi earthquake of 20th Oct, 1991 and Chamoli earthquake of 28th March, 1999. Chamoli earthquake of March 28, 1999 was recorded at 11 different stations of a strong motion array installed in the epicentral region. The maximum peak ground acceleration (353 cm/s2) was recorded at an accelerograph located at Gopeshwar. The data from eleven stations has been used for comparison with the simulated acceleration envelopes due to a model of the rupture responsible for this earthquake. For simulation of acceleration envelope the method of Midorikawa (1993) has been modified for its applicability to Himalayan region. This method has earlier been used by Joshi and Patel (1997) and Joshi (1999) for the studyof Uttarkashi earthquake of 20th Oct, 1991. The same method has been used for study of Chamoli earthquake. Layered earth crust has been introduced in place of homogeneous one in this method. The model of rupture is placed at a depth of 12 km below the Munsiari thrust for modelling Chamoli earthquake. Peak ground acceleration was calculated from simulated acceleration envelope using layered as well as homogeneous earth crust. For the rupture placed in a layered crust model peak ground acceleration of order 312 cm/s2 was simulated at Gopeshwar which is quite close to actually recorded value. The comparison of peak ground acceleration values in terms of root mean square error at eleven stations suggests that the root mean square error is reduced by inclusion of a layered earth crust in place of homogeneous earth crust. 相似文献
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2018年1月20日乌鲁木齐县发生MS4.8地震,乌鲁木齐市区多处震感强烈。此次地震新疆强震台网共获取36条地震动加速度记录,距离震中21.8km的草原工作站烈度速报台记录到本次地震最大峰值加速度97.1×10^-2m/s^2(NS向),距离震中最近的永丰镇峰值加速度70.8×10^-2m/s^2(NS向)。经计算永丰镇仪器烈度为5.5度,与现场工作队考察结果基本一致。对获取到的地震动加速度进行频谱分析,卓越频率集中在2~8Hz范围内,这可能是造成永丰镇建筑物出现轻微破坏的原因之一。将峰值加速度与经验性衰减关系进行对比,震中距小于33km时,水平峰值加速度普遍高于经验性衰减关系。 相似文献
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In this paper, we use seismic waveform simulation to investigate the influence of source mechanism complexity, surface topography, and quality factor on the observed peak ground motions in May 28, 2004, moment magnitude (Mw) 6.2 Baladeh earthquake. The observed peak ground acceleration (PGA) pattern in this event, which is the biggest earthquake to hit the Central Alborz Mountains of Iran in modern instrumental era, is irregular in some respects. First, the observed PGA contours are elongated toward north-west and, second, the maximum observed PGA value of 1049 cm/s2 on the horizontal component of Hasan Keyf station 50 km away from the epicenter is quite high and irregular for an earthquake of this magnitude, at such long distance. In this study, we employ the spectral element method, implemented in SPECFEM3D software package to simulate the 3D wave propagation from several source models in the area. Our results suggest directivity effect is the main cause of the anomalous observations in this earthquake and could account for the elongation of PGA contours and also the anomalous maximum PGA value observed at Hasan Keyf strong motion station. We show that the surface topography has minor effect on the observed peak ground acceleration and the resulting PGA maps. Also by finding the bounds of seismic quality factor effect on the peak ground acceleration values, we show that this factor could not account for the elongation of iso-acceleration contours in the north-west direction. 相似文献
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Topographic site effects of Xishan Park ridge in Zigong city,Sichuan considering epicentral distance
Ma Qiang Wang Fuchen Tao Dongwang Xie Quancai Liu Heyi Jiang Peng 《Journal of Seismology》2021,25(6):1537-1555
Ground motion amplification induced by topography plays a vital role in engineering seismology. A topographic array of 8 accelerographs has been operating along the ridge in Xishan Park since 2007. The topographic site effects in Zigong city are studied based on the strong motion data of 2008 Ms 8.0 Wenchuan earthquake (the epicentral distance?=?225 km) and 2019 Ms 5.2 Zizhong earthquake (the epicentral distance?=?29 km). We compare the peak ground acceleration (PGA) of the two earthquakes and find that the PGA of Station 7#, which locates on a relatively steep slope, is amplified by 4.41 times comparing with the reference station in Zizhong earthquake, while this value is only 1.62 in Wenchuan earthquake. Fourier amplitude spectrum shows that the high frequency content of Zizhong earthquake is more abundant because of its smaller epicentral distance. By using the standard spectral ratio (SSR) method, we conclude that the amplification occurs because high-frequency ground motion is likely to resonate at small-scale features. Finally, the 3D numerical simulations are used to verify these conclusions. Our work indicates that more sophisticated numerical models need to be established for more accurate topographic site effects quantification. In addition, the influence of nearby topographic features should be considered when selecting reference stations.
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A. Joshi 《Journal of Seismology》2003,7(1):1-17
State of Uttaranchal in the northern part of India in the Garhwal Himalaya was hit by the Chamoli earthquake on 28th March, 1999 (GMT). This earthquake was recorded on a strong motion array installed in this region. The maximum peak ground acceleration of 353 cm/sec2 was recorded at an accelerograph located at the Gopeshwar station at an approximate epicentral distance of 14 km. The simplified method of Midorikawa (1993) has been used to model finite fault responsible for causing the Chamoli earthquake. This method is based on the Empirical Green's Function (EGF) technique of Irikura (1986).Modifications in this method have been made to include layered earth model and transmission effects at each boundary by Joshi (2001). Rupture causing the Chamoli earthquake is placed in two structural models of the earth in this work: one is a homogeneous half space and other is the multi layered earth model. Comparison in terms of root mean square error (RMSE) is made between the simulated and actual strong motion parameters like peak acceleration and duration. It is seen that the introduction of multi layered earth system in this simplified technique is capable of significantly reducing the RMSE in observed and predicted strong motion parameters and defining the attenuation rate for peak ground acceleration of this earthquake. 相似文献
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The regularities in the radiation and propagation of seismic waves within the Baikal Rift Zone in Buryatia are studied to estimate the ground motion parameters from the probable future strong earthquakes. The regional parameters of seismic radiation and propagation are estimated by the stochastic simulation (which provides the closest agreement between the calculations and observations) of the acceleration time histories of the earthquakes recorded by the Ulan-Ude seismic station. The acceleration time histories of the strongest earthquakes (M W ~ 3.4–4.8) that occurred in 2006–2011 at the epicentral distances of ~96–125 km and had source depths of ~8–12 km have been modeled. The calculations are conducted with estimates of the Q-factor which were previously obtained for the region. The frequency-dependent attenuation and geometrical spreading are estimated from the data on the deep structure of the crust and upper mantle (velocity sections) in the Ulan-Ude region, and the parameters determining the wave forms and duration of acceleration time histories are found by fitting. These parameters fairly well describe all the considered earthquakes. The Ulan-Ude station can be considered as the reference bedrock station with minimum local effects. The obtained estimates for the parameters of seismic radiation and propagation can be used for forecasting the ground motion from the future strong earthquakes and for constructing the seismic zoning maps for Buryatia. 相似文献