山东省地震烈度速报系统研制与应用

发展地震烈度速报系统是我国现阶段防震减灾事业的一项重要工作.其目的是在地震发生后,对强震动数据进行实时分析和处理,快速给出强震对地表的破坏程度——地震烈度分布图.鉴于目前国内强震动台网分布密度及数据传输方式等诸多因素的限制,多数烈度速报系统是基于美国的ShakeMap系统进行二次开发生成烈度分布图,其计算过程更多地依赖于对地震破裂过程的反演及地震烈度衰减关系,产出的烈度图是静态位图,分辨率较低,与丰富的地理信息难以无缝衔接(Wald et al,1999a;张晁军等,2010;泽仁志玛等,2006).     

山东省地震烈度速报系统研制与应用

发展地震烈度速报系统是我国现阶段防震减灾事业的一项重要工作.其目的是在地震发生后,对强震动数据进行实时分析和处理,快速给出强震对地表的破坏程度——地震烈度分布图.鉴于目前国内强震动台网分布密度及数据传输方式等诸多因素的限制,多数烈度速报系统是基于美国的     

考虑不确定性的地震烈度与地震动参数关系研究

采用97次地震中800个强震动观测台站所获得的强震动记录及震后调查地震烈度作为基础数据,得到地震烈度与地震动参数PGA和PGV并不是一个确定性的对应关系,不确定性是一种客观存在,提出考虑不确定性的地震烈度与地震动参数关系研究。研究结果表明log PGA和log PGV的频数分布图在数据多的情况下符合正态分布,进而给出了考虑不确定性的地震烈度与地震动参数的概率公式,并给出了各个烈度下的参数拟合方法及结果。最后给出了新的考虑不确定性的地震烈度与地震动参数的概率公式在烈度快速评估中的应用。根据贝叶斯公式可以由某一场地的台站记录到的地震动参数来估计其地震烈度的可能性,即概率大小。根据某地区所有台站点的地震烈度期望与标准差,可得到整个地区的地震烈度评估期望图和标准差图,并给出了新疆呼图壁6.2级地震烈度评估的实例应用。     

地震动参数速报仪的研制

在出现区域大震后,为了迅速展开有效的应急救援行动,需要及时准确了解烈度分布.目前震动图的获得有震后人工调查、震源参数计算、地震监测台网、地震烈度速报台网等几种方式,其中最有效的是在重点监护区建立烈度速报台网.但烈度速报台网建设往往沿用地震监测台网的模式,建设成本高、台站密度有限、实时数据传输量大.本文研制的地震动参数速报仪采用MEMS加速度计为测震传感器和ARM+Linux嵌入式计算机技术,具有体积小、成本小、功耗低、一体化、智能化的特点;其内置地震信息实时处理算法,能够自动判别地震事件并计算地震动参数;在实际应用中安装简便.通过大量密集布设这种小型仪器而组建的地震动参数速报网络,具有数据传输量小、分布式计算、组成的速报网络可靠性高、能够快速产出高分辨率的精细震动图等特点.     

SeisMIS地震烈度速报信息发布系统的设计与应用

针对地震信息系统应当在大地震发生后快速发布地震烈度速报信息的需求,结合国际烈度速报信息发布系统建设经验,设计并实现SeisMIS地震烈度速报信息发布系统,并在成都市烈度速报台网中进行应用,对于提升地震烈度速报信息的网络化应用有较好的参考价值.     

2020年10月22日四川北川MS4.7地震强震动特征分析

2020年10月22日11时03分37秒四川省绵阳市北川县发生MS4.7地震,四川强震动台网与预警烈度速报台网在震区建成较密集的台站,获取了532组三分量加速度记录,有助于开展区域地震动衰减和地震动特征研究.本文对强震记录进行常规处理后计算出强震动记录的相关参数,利用克里金插值方法得到地震动峰值加速度PGA和峰值速度PGV的空间分布图,长轴呈北西—南东方向.分析强震动记录PGA、PGV随距离的衰减规律,与常用衰减关系预测值进行对比,此次地震PGA的衰减特性与俞言祥和汪素云(2006)提出的中国西部地区水平向基岩加速度衰减关系有较好的一致性.北川MS4.7地震获得的密集强震动记录为建立区域衰减关系,以及开展基于经验格林函数方法(EGFM)再现大震强地震动场展布等研究提供了重要的数据支撑.     

SeisMIS系统在烈度速报系统中的应用

针对地震监测信息系统应当在大地震发生后快速发布地震烈度分布信息的需求,本文立足现代信息技术,结合国际烈度速报信息发布系统建设经验,设计并实现辽宁省地震烈度速报信息系统,实现了地震烈度数据信息的综合管理和发布。     

青海玛多7.4级地震烈度快速评估

利用青海地震烈度衰减模型和基于断层最短距离的地震动参数衰减模型对青海玛多7.4级地震的烈度分布进行快速评估,将评估结果与实际烈度图对比分析。研究结果表明:两种模型可以在地震正式速报后1分钟内得到地震烈度分布的快速评估结果,时效性强,可以在最短的时间内为应急指挥和救援工作提供参考;青海地震烈度衰减模型计算结果比较理想化,在大致范围上有一定的参考性,但在重灾区范围上与此次实际结果存在偏差;基于断层最短距离的地震动参数衰减模型的PGV-v_(S30)计算结果较青海地震烈度衰减模型更为精细,在高烈度区的评估中具有较好的实际应用价值;相较于冉洪流等研究的地表破裂与震级的经验关系,Wells等研究的经验关系在本次地震中的适用性更好。文章研究结果在此次实际地震应急响应中进行了应用,为政府应急指挥决策和应急救援提供了重要数据支撑。     

趣味地震学(10):烈度,关乎民生

正地震烈度(Intensity),是一个直接关乎民生的参数。烈度调查,揭示了地表和建筑破坏的程度;烈度速报(又称震动图,ShakeMap),给出了地震动的强弱分布;烈度区划(国外称"地震危险性图",Seismic Hazard Map),为建筑的抗震设防提供了基础依据。在一大堆地震参数里,没有哪个能像它那样与老百姓的关系如此密切,有时甚至会牵动千百万人的行动。道理很明显:地震烈度反映着地震对地表破坏的最终结果(图1)。烈度就是破坏的大     

基于JavaEE设计模式的烈度速报建设与应用

通过对JavaEE设计模式、软件框架和软件能力成熟度模型的研究应用,实现了云南强震动台网中心烈度速报系统的整体建设。在系统总结关键技术的基础上,全面统计了近两年发生的所有5.0级及以上地震烈度速报系统自动生成地震烈度图所需要的时间。通过对比2014年8月3日鲁甸6.5级地震后的地震烈度图与中国地震局现场工作队发布的地震烈度图,结果表明:两者的烈度强度和烈度分布范围一致。此外烈度速报系统产生的地震烈度图显示出的局部场地效应明显,其主要集中在山谷和盆地等人口密集居住区域,应用效果理想。     

Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes

We present the regional ground-motion prediction equations for peak ground acceleration (PGA), peak ground velocity (PGV), pseudo-spectral acceleration (PSA), and seismic intensity (MSK scale) for the Vrancea intermediate depth earthquakes (SE-Carpathians) and territory of Romania. The prediction equations were constructed using the stochastic technique on the basis of the regional Fourier amplitude spectrum (FAS) source scaling and attenuation models and the generalised site amplification functions. Values of considered ground motion parameters are given as the functions of earthquake magnitude, depth and epicentral distance. The developed ground-motion models were tested and calibrated using the available data from the large Vrancea earthquakes. We suggest to use the presented equations for the rapid estimation of seismic effect after strong earthquakes (Shakemap generation) and seismic hazard assessment, both deterministic and probabilistic approaches.     

中强地震活动区地震动衰减关系的确定

地震动衰减关系是影响地震安全性评价特别是地震区划结果的重要因素.我国现行的地震动衰减关系主要是依据6级以上地震的地面运动资料得到的,并没有考虑中强地震的衰减特性.为此,文中利用现有的烈度资料和其他可供参考的研究成果来建立我国中强地震活动区的地震动衰减关系.收集了我国华中、华南、东北等地区的51次地震的烈度等震线资料,运用单随机变量加权最小二乘回归法得到中强地震活动区烈度衰减关系.然后以美国西部地区为参考地区,运用缺乏地震动参数的地震动估计方法-地震对映射法得到中强地震活动区峰值加速度和有效峰值加速度衰减关系.最后,通过与我国强地震区和中强地震区已有的烈度衰减关系和地震动衰减关系的对比,验证了得出的我国中强地震活动区烈度衰减关系和地震动衰减关系的合理性.     

Seismic ground motion relationships in southern China based on stochastic finite-fault model

The characteristics of seismic ground motions in southern China are difficult to determine statistically due to a lack of strong ground motion data. In this study, a stochastic finite-fault ground motion model was adopted to simulate the seismic ground motions at bedrock for southern China, based on parameters derived from small and medium earthquakes that have occurred in the region. From these, the response spectra was estimated. A set of ground motion attenuation relationships was then developed based on simulated peak ground motions and response spectral parameters through regression, which would be applicable for use in engineering practice. Through comparisons, it was demonstrated that the proposed ground motion relationships are generally consistent with those obtained from other reported ground motion attenuation models for southern China.     

Simulation of Ground Motion from Strong Earthquakes of Kamchatka Region (1992–1993) at Rock and Soil Sites

To estimate the parameters of ground motion in future strong earthquakes, characteristics of radiation and propagation of seismic waves in the Kamchatka region were studied. Regional parameters of radiation and propagation of seismic waves were estimated by comparing simulations of earthquake records with data recorded by stations of the Kamchatka Strong Motion Network. Acceleration time histories of strong earthquakes (M _w = 6.8–7.5, depths 45–55 km) that occurred near the eastern coast of Kamchatka in 1992–1993 were simulated at rock and soil stations located at epicentral distances of 67–195 km. In these calculations, the source spectra and the estimates of frequency-dependent attenuation and geometrical spreading obtained earlier for Kamchatka were used. The local seismic-wave amplification was estimated based on shallow geophysical site investigations and deep crustal seismic explorations, and parameters defining the shapes of the waveforms, the duration, etc. were selected, showing the best-fit to the observations. The estimated parameters of radiation and propagation of seismic waves describe all the studied earthquakes well. Based on the waveforms of the acceleration time histories, models of slip distribution over the fault planes were constructed for the studied earthquakes. Station PET can be considered as a reference rock station having the minimum site effects. The intensity of ground motion at the other studied stations was higher than at PET due to the soil response or other effects, primarily topographic ones. At soil stations INS, AER, and DCH the parameters of soil profiles (homogeneous pyroclastic deposits) were estimated, and nonlinear models of their behavior in the strong motion were constructed. The obtained parameters of radiation and propagation of seismic waves and models of soil behavior can be used for forecasting ground motion in future strong earthquakes in Kamchatka.     

Spectral parameters of ground motion in different regions: comparison of empirical models

Fourier-amplitude spectrum is one of the most important parameters describing earthquake ground motion, and it is widely used for strong ground motion prediction and seismic hazard estimation. The relationships between Fourier-acceleration spectra, earthquake magnitude and distance were analysed for different seismic regions (the Caucasus and Taiwan island) on the basis of ground motion recordings of small to moderate (3.5≤M_L≤6.5) earthquakes. It has been found that the acceleration spectra of the most significant part of the records, starting from S-wave arrival, can be modelled accurately by the Brune's “ω-squared” point-source model. Parameters of the model are found to be region-dependent. Peak ground accelerations and response spectra for condition of rock sites were calculated using stochastic simulation technique and obtained models of source spectra. The modelled ground-motion parameters are compared with those predicted by recent empirical attenuation relationship for California.     

基于衰减关系的城镇烈度发生概率快速估计

震后快速产出的震动烈度分布是地震应急救援非常有效的依据, 通常由烈度与地震动参数的经验关系给出. 有台站的场点, 地震动参数可以直接由台站数据给出确定性的结果; 而无台站的场点, 地震动参数只能由衰减关系给出估计值. 目前我国台站覆盖有限, 且难于实时获取, 快速生成的地震动参数主要依赖于地震动衰减关系, 再依据烈度与地震动参数的经验关系, 输出确定性的震动烈度分布. 由于衰减关系本身存在着不确定性, 将其估计值用于生成确定性的震动烈度分布是不准确的. 而且实践证明, 震动烈度与实际调查烈度存在差异. 鉴于此, 从衰减关系模型中的ε出发, 提出了场点(城镇)遭遇不同烈度的概率计算方法: 利用衰减关系的估计值与衰减关系的标准差, 构造峰值加速度(PGA)变化的对数正态分布, 然后以烈度分档对应的PGA范围, 计算震区各城镇遭遇不同烈度的概率及各城镇抗震设防烈度被超越的概率. 具体以1966年3月8日河北邢台M_S6.8地震为例, 说明了此方法的可行性, 认为以概率形式给出城镇可能遭遇的烈度在表述上更为合理, 并建议将场点(城镇)遭遇烈度的概率表达方法用于震害快速评估.      

Source and high-frequency decay parameters for the Azores region for stochastic finite-fault ground motion simulations

Strong ground motion prediction based on finite-fault simulation requires the identification of the fault (strike, dip, length and width), source kinematics parameters (stress drop, rupture velocity and slip distribution), regional crustal properties (geometrical spreading, anelastic structure, and upper crustal amplification and attenuation parameters) and the determination of amplification effects due to the local site geology. The general purpose of this study is to understand source and attenuation properties in the Azores, by the determination of stress drop, quality factor and kappa, through records obtained by the Portuguese digital seismic and accelerometer network. Source Spectra were obtained, for each record, after correcting observed spectra from geometrical spreading and anelastic attenuation effect: quality factor was estimated based on coda decay in the time domain and the kappa parameter was estimated by fitting the high-frequency decay of the acceleration spectrum with a straight line in a log-linear scale. Mean stress drop value was obtained considering that ω-squared model for the source spectra prevails. Parameters kappa, k, and quality factor, Q, have been estimated to be k = (0.075 ± 0.02)s and \(Q(f) = (76 \pm 11)f^{0.69 \pm 0.09}\), respectively. A mean value of stress drop was estimated to be around 90–130 bars for the earthquakes in analysis. The knowledge of source and path parameters, in association with other ground motion parameters, allows improving ground-motion estimates for the Azores and, consequently, will lead to more accurate seismic hazard assessment for the Azores and better characterization of seismic scenarios.     

Seismic hazard analysis for engineering sites based on the stochastic finite-fault method

Seismic hazard analyses are mainly performed using either deterministic or probabilistic methods. However, there are still some defects in these statistical model-based approaches for regional seismic risk assessment affected by the near-field of large earthquakes. Therefore, we established a deterministic seismic hazard analysis method that can characterize the entire process of ground motion propagation based on stochastic finite-fault simulation, and we chose the site of the Xiluodu dam to demonstrate the method. This method can characterize earthquake source properties more realistically than other methods and consider factors such as the path and site attenuation of seismic waves. It also has high computational efficiency and is convenient for engineering applications. We first analyzed the complexity of seismogenic structures in the Xiluodu dam site area, and then an evaluation system for ground motion parameters that considers various uncertainties is constructed based on a stochastic finite-fault simulation. Finally, we assessed the seismic hazard of the dam site area comprehensively. The proposed method was able to take into account the complexity of the seismogenic structures affecting the dam site and provide multi-level parameter evaluation results corresponding to different risk levels. These results can be used to construct a dam safety assessment system of an earthquake in advance that provides technical support for rapidly and accurately assessing the post-earthquake damage state of a dam, thus determining the influence of an earthquake on dam safety and mitigating the risk of potential secondary disasters.     

Ground motion observations and simulation for local earthquakes in the Campi Flegrei volcanic area

Ground motion produced by low magnitude earthquakes can be used to predict peak values in high seismic risk areas where large earthquakes data are not available. In the present work 20 local earthquakes (M_D∈[?0.3, 2.2]) occurred in the Campi Flegrei caldera during the last decade were analyzed. We followed this strategy: empirical relations were used to calibrate synthetic modeling, accounting for the source features and wave propagation effects. Once the source and path parameters of ground motion simulation were obtained from the reference data set, we extrapolated scenarios for stronger earthquakes for which real data are not available. The procedure is structured in two steps: (1) evaluation of ground motion prediction equation for Campi Flegrei area and assessment of input parameters for the source, path and site effects in order to use the finite fault stochastic approach (EXSIM code); (2) simulation of two moderate-to-large earthquake scenarios for which only historical data or partial information are available (M_w4.2 and M_w5.4). The results show that the investigated area is characterized by high attenuation of peak amplitude and not negligible site effects. The stochastic approach has revealed a good tool to calibrate source, path and site parameters on small earthquakes and to generate large earthquake scenario. The investigated magnitude range represents a lower limit to apply the stochastic method as a calibration tool, due to the small size of involved faults (fault length around 200/300 m).     

Seismic ground motion relationship in southern China based on stochastic finite-fault model

The characteristics of seismic ground motions in southern China are difficult to determine statistically due to a lack of strong ground motion data. In this study, a stochastic finite-fault ground motion model was adopted to simulate the seismic ground motions at bedrock for southern China, based on parameters derived from small and medium earthquakes that have occurred in the region. From these, the response spectra was estimated. A set of ground motion attenuation relations hipswas then developed based on simulated peak ground motions and response spectral parameters through regression, which would be applicable for use in engineering practice. Through comparisons, it was demonstrated that the proposed ground motion relationships are generally consistent with those obtained from other reported ground motion attenuation models for southern China.