高频GNSS实时地震学与地震预警研究现状

为实现从注重灾后救助向注重灾前预防转变,如何提高地震灾害监测预警和风险防范能力成为我们关注的重点.本文给出了国际上GNSS位移记录、强震动加速度记录、测震速度记录在地震预警中的应用现状,并总结了各自的特点,归纳出围绕高频GNSS地震学在震级与破裂过程实时反演中的几个需要进一步研究的关键问题：（1）引入北斗系统,基于高频GNSS（GPS/BDS）双系统的实时位移解算方法来提高实时单站位移解算精度,使实时解算精度达到厘米级;（2）开展强震仪加速度记录基线偏移校正研究,弥补地震近场GNSS站密度不足问题;（3）强震仪加速度记录与GNSS位移记录特点不同,开展强震仪加速度数据与GNSS位移数据实时融合处理研究,快速获得包含丰富地震形变和速率的波形数据;（4）测震学方法可快速估算震级,但是在强震发生时会出现震级饱和现象,造成震级估算偏低.需要开展基于GNSS位移时间序列的多种方法相结合的实时震级估算方法研究,通过与地震学方法比较和结合,来得到精度高、计算快的震级估值算法;（5）基于高频GNSS、断层初始模型快速选取、断层尺度、参数自适应调整是快速判断断层破裂方向的基础,在断层破裂过程自适应准实时反演算法方面需要进一步加强.通过国内外研究现状调研、分析,表明基于高频GNSS地震学的震级快速确定、震源破裂过程准实时反演算法的发展将对我国地震预警系统从"二网融合"到"三网融合"提供坚实的技术支撑.     

An Introductory Overview of Earthquake Early Warning

Earthquake early warning (EEW) is discriminated from earthquake prediction by using initial seismic waves to predict the severity of ground motion and issue the warning information to potential affected area. The warning information is useful to mitigate the disaster and decrease the losses of life and economy. We reviewed the development history of EEW worldwide and summarized the methodologies using in different systems. Some new sensors came and are coming into EEW giving more developing potential to future implementation. The success of earthquake disaster mitigation relies on the cooperation of the whole society.     

模拟PLUM方法在2021年日本福岛县近海M7.3级地震中的表现

2021年2月13日晚,日本福岛县近海发生M7.3级地震,产生强烈振动,此次地震被认为是"3.11"地震的余震。首先介绍了PLUM方法的原理及日本气象厅地震预警系统对于PLUM方法的应用,评述了JMA地震预警结果。通过模拟PLUM方法在此次地震中的表现,由预测精度和有效预警时间两个指标来评估该方法的性能,并与日本气象厅发布的预警信息对比。模拟结果显示:受限于地震数据以及PLUM方法本身的原理,在震后第24 s发出第一次警报,不及使用P波预警与PLUM相结合的JMA地震预警系统及时。在地震前期0~40 s处于烈度剧烈上升阶段,预测精度较差;40 s之后的预测结果较为准确,预测精度高达100%。PLUM方法可以有效克服点-源模型中的弊端,特别是在多个地震同时发生的情况下预警效果良好,将PLUM方法纳入我国地震预警系统可以有效提高预警能力。     

Earthquake early warning: Concepts,methods and physical grounds

Modern technology allows real-time seismic monitoring facilities to evolve into earthquake early warning (EEW) systems, capable of reducing deaths, injuries, and economic losses, as well as of speeding up rescue response and damage recovery. The objective of an EEW system is to estimate in a fast and reliable way the earthquake’s damage potential, before the strong shaking hits a given target.     

A macroseismic intensity prediction equation for intermediate depth earthquakes in the Vrancea region,Romania

The use of shake maps in terms of macroseismic intensity in earthquake early warning systems as well as intensity based seismic hazard assessments provides a valuable supplement to typical studies based on recorded ground motion parameters. A requirement for such applications is ground motion prediction equations (GMPE) in terms of macroseismic intensity, which have the advantages of good data availability and the direct relation of intensity to earthquake damage. In the current study, we derive intensity prediction equations for the Vrancea region in Romania, which is characterized by the frequent occurrence of large intermediate depth earthquakes giving rise to a peculiar anisotropic ground shaking distribution. The GMPE have a physical basis and take the anisotropic intensity distribution into account through an empirical regional correction function. Furthermore, the relations are easy to implement for the user. Relations are derived in terms of epicentral, rupture and Joyner–Boore distance and the obtained relations all provide a new intensity estimate with an uncertainty of ca. 0.6 intensity units.     

Automated Estimation of Seismic Shaking Intensity from Instrumental Data in Quasi-Real-time Mode and Its Use in the Operation of the of Seismic Early Warning Service in the Kamchatka Region

Early warning systems are becoming increasingly important in the modern world. These systems combine several components: predictive systems (For example, tsunami warning systems), earthquake early warning systems, emergency message services, and systems of seismic damage monitoring. Information about shaking intensity becomes especially important in the case of a strong earthquake occurrence. These data are necessary for planning emergency rescue operations, but they are difficult to collect in a natural disasters situation because of possible communication problems. Application of data on instrumental seismic intensity may make it possible to solve this problem. Early warning systems predicting seismic intensity distributions just after the occurrence of an earthquake have already been developed in many seismically active regions of the world. Such a system also needs to be implemented in Kamchatka, where the strongest earthquakes can produce extremely high values of strong motion acceleration. As a result of the development of a system for seismological observation in Kamchatka, a unified specialized system for collection, transmission, archiving, and processing of seismic information was created. Seismological observations in Kamchatka were significantly improved with the update of the tsunami warning service in 2006–2011. As a result, a network of strong motion stations is currently operating in Kamchatka and can serve as a basis for creating a quasi-real-time seismic early warning system under the auspices the Kamchatka Branch of the Geophysical Survey, Russian Academy of Sciences (KB GS RAS). It uses data from strong motion stations to estimate the instrumental seismic intensity in quasi-real-time mode and visualizes the results. During the operational period while the service is being intensively used in the framework of the Seismic Early Warning Reports Tsunami Warning Service in the Kamchatka and Sakhalin branches of the GS RAS for real-time warning of interested parties about the shaking intensities at observation points, the technology implemented in this service has proved highly informative. In total, 75 messages on instrumental intensity in various places of Kamchatka krai and the northern Kuril Islands (Paramushir Islands) have been sent since the service was commissioned at the end of 2014. The currently operating version of the service has proved its informativeness and applicability for special departments of the Emergency Situations Ministry. In addition, real-time warning has improved coordination between the departments of KB GS RAS, and the results of this system are being used in a number of basic research projects. Further development of the service is related to the creation of denser instrumental networks to record strong ground motions and the transition to automatic decision-making and message sending.     

Real-time 3-D space numerical shake prediction for earthquake early warning

In earthquake early warning systems, real-time shake prediction through wave propagation simulation is a promising approach. Compared with traditional methods, it does not suffer from the inaccurate estimation of source parameters. For computation efficiency, wave direction is assumed to propagate on the 2-D surface of the earth in these methods. In fact, since the seismic wave propagates in the 3-D sphere of the earth, the 2-D space modeling of wave direction results in inaccurate wave estimation. In this paper, we propose a 3-D space numerical shake prediction method, which simulates the wave propagation in 3-D space using radiative transfer theory, and incorporate data assimilation technique to estimate the distribution of wave energy. 2011 Tohoku earthquake is studied as an example to show the validity of the proposed model. 2-D space model and 3-D space model are compared in this article, and the prediction results show that numerical shake prediction based on 3-D space model can estimate the real-time ground motion precisely, and overprediction is alleviated when using 3-D space model.     

地震综合信息多渠道发布系统设计与实现

针对地震速报信息、地震预警信息发布渠道单一，无法与地震应急成员单位进行及时有效信息的共享问题，天津市地震局对接市突发公共事件预警信息发布系统、武警总队参谋部和中新生态城智慧城市管理中心，通过开发综合信息发布平台，以国际通用预警CAP协议数据包的形式向成员单位实时推送地震预警、速报信息，实现通过电视媒体、预警终端、短信平台发布地震实时信息的目的，同时各应急成员单位通过地震信息服务系统推送的信息快速生成各单位相应的应急处置方案，为地震应急救援工作提供依据。     

高速铁路与国家地震台网信息接入及资源共享方式研究

本文对高速铁路与国家地震台网信息接入和资源共享方式进行了讨论。通过对组网模式和时延的分析及测试,在遵循目前地震系统信息传输模式的前提下,对于实时波形数据,可以根据实际情况采取国家中心型或者省局中心型的方式进行共享,用于高铁系统台站的补充,在地震预警发布阶段使用;对于地震速报信息,可以采取国家中心型的方式进行共享,用于地震信息的确认,在地震预警解除阶段使用。为了减小实时数据传输的时延以适应预警需求,应对数据采集器进行升级,并更新相应的流服务器的仪器适配器。     

中国地震台网现状及其预警能力分析

本文讨论了影响地震预警能力的决定性因素. 通过对我国现有地震台网布局、 数据传输延时和台网运行状况等方面的讨论, 对能否满足地震预警需求进行了分析, 并对台网现状的改进提出了相应的建议. 总体来说, 中国地震台网现状并不能满足地震预警需求, 除了需要对台网进行加密和提高相应的运行率之外, 还应对现有数据采集器和实时传输软件进行必要升级, 以达到地震预警对数据延时的需求.      

Rapid Earthquake Information for Bucharest

Advances in sensor techniques, digital acquisition, communication and computing allowed establishment of the field of real-time seismology (Kanamori et al., 1997) and the design of earthquake information systems that provide rapid information on ground motion and potential damage in an area for which a ground motion estimation data base is available and where the inventory of buildings and infrastructure and its vulnerability to shaking is known. We discuss a system for the Romanian capital of Bucharest, where an early warning system with about 30 seconds lead time, shake maps and a sophisticated damage estimation tool for Bucharest have been developed in the frame of the Collaborative Research Center on Strong Earthquakes ().     

高速铁路地震预警系统控车方案研究

随着中国高速铁路建设的飞速发展,对高速铁路地震预警系统的要求越来越迫切。目前我国建成的几条高速铁路地震监测及预警系统,都是在铁路沿线布置的台网,没有与当地地震台网实现地震信息共享,对于地震的精确定位以及强度估计存在一定的偏差。在高速列车快速制动后,如果能从地震台网获得相应的地震信息,对于制定高速列车恢复行车策略能够起到很大的作用。本文在对国外和国内高速铁路地震预警系统建设调研的基础上,结合我国目前建设的地震预警系统实际情况,提出了高速铁路地震预警系统快速制动及恢复行驶方案,以期对我国下一步高速铁路地震预警系统的建设提供参考。     

日本地震预警系统发展历程

地震预警（EEW）或实时地震预警系统是指,几秒内检测到临近区域可能发生的强烈地震后,对本地提供预警信息的系统。地震预警的目标是,通过相应决策让人们能够在多种环境中保护自己,并减轻与地震相关的次生灾害。本文详细介绍了地震预警系统在日本的发展历程,指出预警信息已不再局限于向高级用户和公众用户进行发布,私人定制用户已成为预警信息发布的重要需求。未来地震预警技术的发展,特别是实时断层源成像识别技术,对改善预警系统并快速识别震源参数具有重要意义。     

地震预警系统的效能评估和社会效益分析

本文从地震预警系统可减少的人员伤亡和可挽回的经济损失两个角度出发, 研究了地震预警系统的效能和社会效益. 通过对兰州市及周边地区潜在震源各个震级档的年平均发生概率进行计算, 并结合以兰州市为中心布设的80个强震预警台站信息, 计算了有效的预警时间及地震烈度. 基于生命易损性模型方法, 计算了地震预警系统可减少的人员伤亡系数; 采用基于宏观GDP的损失评估方法, 计算了地震预警系统可减少的经济损失, 分析了地震预警系统的社会效益. 计算结果表明: 减小地震预警盲区范围对提高地震预警系统的效能非常关键; 地震预警系统的建设和台网布局应重点考虑布设区域的人口密度、 经济情况及地震发生概率.      

2010年新西兰MW7.0主震与2011年MW6.1余震近场强地面运动特征比较分析

2010年9月3日16时35分46秒新西兰南岛Greendale附近发生了M_W7.0地震, 震源深度约10.0 km. 2011年2月21日新西兰南岛又发生了M_W6.1地震, 为2010年M_W7.0主震后最大的一次余震, 震源深度约5.0 km, 发震断层为Christchurch南约9 km一条近东西走向逆冲的隐伏断层, 该地震造成Christchurch城内多处建筑物严重损毁. 本文分析了2010年新西兰地震事件M_W7.0主震与M_W6.1余震强地面运动的特征. 新西兰M_W6.1余震近场强地面运动整体高于M_W7.0主震. 将主震和余震的强震观测记录分别与新一代衰减关系(NGA)进行对比, 发现余震强震观测数据整体高于其震级对应的NGA. 分别选取距离主震和余震震中最近且强震观测记录最高的两个台站(GDLC台站和HVSC台站)作为参照台站, 建立动态复合震源模型(DCSM)及有限断层随机振动模型(SFFM)进行强地面运动的模拟计算, 分析两种模型的模拟结果并对比二者的优势及局限, 以便在未来工作中更好地通过模型计算强地面运动特征, 实现区域化特征快速、 实时分析及局部重点、 细致分析相结合的目标.      

地震前兆的复杂性及地震预报、预警、预防综合决策问题的讨论——浅释唐山、海城、松潘、丽江等大地震的经验教训

唐山地震、 海城地震、 松潘地震和丽江地震等大地震的观测与预报实践, 在科学上提出许多问题, 但最重要的是地震前兆复杂性的理解和认识问题。 从上述大地震的重要观测资料中, 得到对大地震的短临前兆复杂性及其表现形式的新理解, 认为: 短临前兆异常不同于趋势异常, 异常现象的突发性、 差异性、 特殊的无序和不稳定性, 不可重复性是其主要特征。 其“场, 源”关系, 也不同于一般概念的“场, 源”关系, 它具有“混沌”性能。 前兆异常复杂性产生的根源不仅是因为孕震系统是复杂的系统, 更为重要的是, 当系统进入非弹性应变阶段后, 受到非线性动力学一般原理所支配。 因此地震及其前兆现象似乎是不可能在纯力学的基础上加以探索研究的, 准确地说, 它们应该视为在远离平衡的条件下起作用的非线性动力学体系一般性问题的组成部分。 块、 带、 源、 兆整体协同分析和长(期), 中(期)、 短(期)、 临震预报相结合的渐进式地震预报思路, 是地震预报成功与失败的实践经验总结。 只有在整体上, 从时间、 空间结构统一性上进行综合分析研究, 才有可能抓住地震及其前兆复杂性问题的本质。 该文还讨论了地震及其预报对社会的影响, 和地震预报需要面对的社会问题, 以及制约、 影响地震预报和预警的因素。 文中认为与其它自然灾害相比, 地震预报和灾害预警的难度更大, 每一步骤的决策, 无论是警报发布、 级别调整、 警报的解除都包含了许多不确定性和风险。 实践经验证明: 政府对地震预报、 预警、 预防的综合决策是有效减轻地震灾害和风险的关键。     

实时GNSS地震仪系统实现及精度分析

高频GNSS数据实时精密单点定位(RTPPP)可实时获得地表瞬时动态形变和地震波信号,为地震参数快速确定、地震快速响应及海啸预警提供实时的观测资料.本文构建了实时GNSS地震仪系统,主要包括RTPPP和实时探测两部分.利用RTPPP 方法处理了模拟的震动实验平台实验数据和2010年Baja California地震的数据,并与惯导(IMU)、事后PPP和差分相对定位结果比较,定量评估了实时GNSS地震仪系统的精度.结果表明,该系统可实现水平方向优于1cm,高程方向优于3cm的实时定位,且对Baja California地震的实时探测结果与南加州地震数据中心公布的结果相一致.     

Istanbul Earthquake Rapid Response System: Methods and practices

Potential impact of large earthquakes on urban societies can be reduced by timely and correct action after a disastrous earthquake. Modern technology permits measurements of strong ground shaking in near real-time for urban areas exposed to earthquake risk. The Istanbul Earthquake Rapid Response System equipped with 100 instruments and two data processing centers aims at the near real time estimation of earthquake damages using most recently developed methodologies and up-to-date structural and demographic inventories of Istanbul city. The methodology developed for near real time estimation of losses after a major earthquake consists of the following general steps: (1) rapid estimation of the ground motion distribution using the strong ground motion data gathered from the instruments; (2) improvement of the ground motion estimations as earthquake parameters become available and (3) estimation of building damage and casualties based on estimated ground motions and intensities. The present paper elaborates on the ground motion and damage estimation methodologies used by the Istanbul Earthquake Rapid Response System with a special emphasis on validation and verification of the different methods.     

Real-time numerical shake prediction and updating for earthquake early warning

Ground motion prediction is important for earthquake early warning systems, because the region’s peak ground motion indicates the potential disaster. In order to predict the peak ground motion quickly and precisely with limited station wave records, we propose a real-time numerical shake prediction and updating method. Our method first predicts the ground motion based on the ground motion prediction equation after P waves detection of several stations, denoted as the initial prediction. In order to correct the prediction error of the initial prediction, an updating scheme based on real-time simulation of wave propagation is designed. Data assimilation technique is incorporated to predict the distribution of seismic wave energy precisely. Radiative transfer theory and Monte Carlo simulation are used for modeling wave propagation in 2-D space, and the peak ground motion is calculated as quickly as possible. Our method has potential to predict shakemap, making the potential disaster be predicted before the real disaster happens. 2008 M _S8.0 Wenchuan earthquake is studied as an example to show the validity of the proposed method.     

Applications of cumulative absolute velocity to urban earthquake early warning systems

An early warning system forewarns an urban area of the forthcoming strong shaking, normally with a few seconds to a few tens of seconds of early warning time before the arrival of the destructive S-wave part of the strong ground motion. For urban and industrial areas susceptible to earthquake damage, where the fault rupture system is complex and the fault-site distances are short, there is usually insufficient time to compute the hypocenter, focal parameters and the magnitude of an earthquake. Therefore, simpler and robust early warning algorithm is needed. The direct (engineering) early warning systems are based on algorithms of the exceedance of specified threshold time domain amplitude levels. The continuous stations’ data are processed to compute specific engineering parameters robustly and compared with specified threshold levels. The parameters can be chosen as band-pass filtered peak ground accelerations and/or the bracketed cumulative absolute velocity (BCAV). In this paper, an enhancement to bracket cumulative absolute velocity for the application of online urban early warning systems results in a new parameter called window based bracketed cumulative absolute velocity (BCAV-W). The BCAV-W allows computation of cumulative absolute velocity in a specified window size and to include the vertical component of the motion. The importance of choosing optimum window size for the cumulative absolute velocity BCAV-W is discussed and the correlations between BCAV-W and the macro-seismic intensity are studied for three combinations of horizontal and vertical components of the motion. Empirical relationship is developed to estimate BCAV-W as a function of magnitude, distance, fault mechanism, and site category based on 1,208 recorded ground motion data from 75 earthquakes in active plate-margins.