地震预测与统计物理

将现代统计物理学的理论和方法应用于地震和地震预测问题的研究，近年来取得了长足的进展，成为物理学和地震学之间一个最为活跃的交叉领域，这一领域所取得的成果，例如，将地震作为一种临界现象的模型，不仅丰富和深化了对地震的认识，而且改变了地震预测研究中的一些传统观念。文章介绍了这方面的研究进展，讨论了与这一领域相关的一些重要的物理概念和悬而未决的科学问题。     

从弹簧滑块到地震预测:BK模型今昔谈

Burridge-Knopoff弹簧－滑块模型作为一个概念性的地震模型，自1967年提出以来一直为地震学家和物理学家所关注，对BK模型的研究成为物理学与地震学之间的一个活跃的交叉领域，BK模型的一些性质，例如确定性浑沌，自组织，孤立波，等等，能够为理解地震的性质和解决地震预测问题提供有用的线索，BK模型与目前的一些悬而未决的复杂性物理问题的联系，使它不仅对地震研究，而且对更普遍的多体系统问题的研究，都有重要的影响。     

与地震预测预报有关的几个物理问题

文章简要介绍了与地震预测预报有关的几个物理问题,包括地震活动性问题、地球深部物质的物理性质及其变化问题、地球深部的流体问题、地震破裂问题、地球深部的形变和应力问题.这些问题的研究涉及当代物理学的一前沿领域.唐山大地震后30年来有诸多重要进展.     

寂静地震与地震预测的物理问题

寂静地震是指发生了缓慢的位错、但几乎不辐射地震波的“地震” .在目前的地震预测的物理学研究中 ,通常是通过计算历史上曾经发生过的地震所引起的应力变化 ,或者通过研究地震活动的统计性质或“图像动力学” ,来推测一个断层带上发生地震的危险性 .寂静地震的信息的缺失 ,形成了地震预测的物理学研究中的一个很大的“盲区” ,而在相当程度上 ,解决地震预测的物理问题的主要困难和可能的突破的希望 ,也许就在于此 .寂静地震的研究目前还很不深入 .关于寂静地震的性质 ,文章作者提出两个猜想 :(1)寂静地震的频度 ,满足类似于GR定律的幂律分布 ;(2 )最大的寂静地震的地震矩 ,与“可见”的最大地震的地震矩相当 .     

数值地震预测的关键物理问题*

数值地震预测是地震物理研究中的一个重要课题,具有基础性的科学意义和潜在的应用价值.文章介绍了数值地震预测的三个关键物理问题——地震发生率与应力变化的关系、地震断层的摩擦函数、地球中应力的传递问题,讨论了这些问题的意义、研究现状和发展趋势.     

地震预报的物理学问题

近年来，运用非线性物理学的概念和方法去理解地震现象的复杂性的研究取得引入瞩目的进展。用临界现象理论来理解地震破裂的物理过程，从自组织临界现象的角度对中长期时间迟度上的地震活动进行说明，这都给地震预报研究以很大的启发，并在实际地震预报算法的研究中得应用。地震预报目前仍是一个世界性的科学难题。用物理学的概念和方法研究地震和地震预报问题，可能是地震预报和减轻地震灾害研究中一个有希望的发展方向。这篇综述的     

矿山地震、瓦斯突出、煤岩体破裂——煤矿安全中的科学问题

文章介绍了矿山地震和瓦斯突出等煤矿灾害及成因，并通过若干煤矿瓦斯突出和矿山地震的同震现象，论述了这些灾害在动力过程中的内在关系．这些震例表明，在高瓦斯煤矿，矿山地震与瓦斯突出存在密切的相关．认为较大矿震加上瓦斯的低值延时响应可能是瓦斯突出的预警信号．建立矿震（冲击地压）与瓦斯突出联合监测和预警系统，是维护矿山安全，减轻矿山灾害的重要途径．从矿震定位、震源机制、矿震成因、瓦斯突出条件分析了矿震与瓦斯突出相关的机理．为矿震和瓦斯的联合监测和灾害预警提供了科学依据．进一步介绍了瓦斯流体对矿震的触发作用，尤其超临界流体的特殊性质在矿震发生中的重要作用．     

地震灾害风险：物理的预测与预测的物理

<正>地震预测是一个世界性科学难题~([1])。但这并不等于说防震减灾(也应该)是一个实践难题。一定程度上,在防震减灾的实际应用中,不同时空尺度的不同地震现象的预测及其对减轻地震灾害风险的作用,是一个更重要的科学问题。1地震预测的作用的"现代"理解减灾的"第一原理"~([2])是灾害风险(Risk,简记为R)取决于三项的     

以颗粒物理原理认识地震——地震成因、地震前兆和地震预测

本文以地壳和地幔的基本构造和己有观测事实为依据,运用颗粒物理原理,将地壳和地幔作为大尺度离散态颗粒物质体系处理,重新认识地震孕育过程,前兆产生机制及规律,探求地震预测方法和途径.主要结果是:建立了地壳与地幔构成和运动的颗粒模型;提出了引发地震的大地构造力的形成机制,以及地震前兆信息产生和传播规律;说明了地震前兆信息的主要特征及其与地震发生之间的关联,阐述了探测有效地震前兆信息的方法原理;用颗粒流动的阻塞-解阻塞转变原理解释了深源地震发生机制;对以前难以理解的若干地震学现象进行了解释,并讨论了地震的可预测性。由于地壳和地幔的离散结构特征,对于地震孕育的准静力学过程,连续介质理论不再适用.以颗粒物理原理研究地震成因、地震前兆和地震预测,所获得的新认识与传统连续介质地震学观点有本质区别。     

海啸的物理

地震海啸的产生是地球表面固体层和流体层相互作用的结果．文章介绍了这种相互作用的物理过程，讨论了海啸的大小、能量、传播速度．指出：建立早期预警系统是减少海啸灾害的重要措施，目前的预警系统虚报率很高的问题，仍需要通过加强地球表层系统相互作用的研究来解决．     

高分辨率多光谱的芦山地震次生地质灾害遥感监测与评估

2013年4月20日芦山7.0级大地震发生后,产生大面积滑坡、崩塌、碎屑流等次生地质灾害,造成大量人员财产损失,并严重阻碍了应急救援和灾后重建工作的顺利开展。利用快速获取的震前和震后航空、航天等多源遥感数据、地形地貌和地质构造数据,首先结合次生地质灾害在高分辨率多光谱影像上的形态、结构和纹理特征,对地震重灾区次生地质灾害的数量和空间分布进行了有效监测。结果显示：芦山县、宝兴县和天全县次生地质灾害最为严重,各有164处、126处和71处大型次生地质灾害点。并结合GIS技术对这些次生地质灾害的空间分布规律,特别是同区域地质构造、烈度和地形地貌之间的关系进行了综合分析和评估。评估结果显示：在监测区存在四个次生地质灾害高发区,其中一个聚集在震中6公里范围内,其他三个沿本区域两个主要地质断层分布;超过97%的次生地质灾害位于烈度Ⅶ～Ⅳ度、坡度25°～50°且海拔800～2 000 m之间的区域。最后结合震害遥感监测评估结果,对震后恢复重建规划及实施提出建议。     

海啸、地震海啸与海啸地震

简要地介绍了海啸与地震海啸的成因、特点,分析了影响地震海啸的重要因素,阐述了海啸预警的物理基础.以2004年12月26日苏门答腊-安达曼MW9.0特大地震及其激发的印度洋特大海啸为例,说明除了地震的大小、地震机制、震源深度以外,震源破裂过程也是影响地震激发海啸的重要因素.通过对苏门答腊-安达曼特大地震及2005年3月28日苏门答腊北部特大地震进行分析对比,探讨了海啸地震的特征,阐明了进一步深入研究海啸地震的特征及其激发海啸的机制对于预防和减轻海啸灾害的重要意义.     

层状材料褶皱对几种地质活动机理研究的启示

从制备层状材料褶皱得到启示,给出了地球地质活动的一些可能的机理性解释.层状晶体的褶皱可以通过在柔性基底上施加的单轴或双轴应力实现,这与地球的层状结构及地球表面的山体褶皱形成机理有许多相似之处.由于地球质量分布不均匀且存在自转,因此各个板块的转动惯量是不一样的,本文指出南北半球之间存在自转角速度差异,对赤道附近的地形地貌及地质活动可能产生重要影响.本文给出了地震、火山以及大陆漂移等地质活动新的机理解释.针对中国特殊的地形地貌,提出了物质流假说并详细论述了物质流的流动趋势,指出中国大陆地质活动和板块交界处的地质活动的机理存在明显差别.物质流假说可以较好地解释中国的地震灾害、矿藏资源分布及中东地区石油丰富的可能成因,为中国未来预测地震灾害及矿藏资源开发提供了新的理论参考.该工作为人类更好地避免自然灾害、理解地球上的自然现象及合理利用自然资源提供了新的启示.     

Earthquake hazard and risk mitigation

Earthquake risk is the combination of three factors: the earthquake hazard, the loss potential and the vulnerability. To examine the risk it is first necessary to consider the global distribution of earthquakes, their size and their frequency of occurrence. Migratory trends and temporal patterns of activity are sought as a means of defining the locations of future seismic hazard. It is important also to appreciate the kind of damage that is brought about by an earthquake, including the social and economic effects that can follow. Where loss potential is high, in areas of high population density, and where there is a known hazard from earthquakes, it is vital to mitigate the risk by reducing the vulnerability so far as possible. This can best be achieved through earthquake-resistant construction of buildings and other structures, but there are limits to what can be achieved. Consequently earthquake prediction may prove an alternative, complementary approach that could at least save lives. A range of possible precursory phenomena have been discovered, a number of which can be related empirically to the size and time ahead of an impending earthquake, but since the physical mechanism of earthquakes is still poorly known, these phenomena have only a weak scientific basis. At present none are established as definite precursors, and although a few successful predictions have been claimed, there are too many failures to predict, and too many false alarms, for Predictions to be reliable or credible. For the time being, as research progresses, the uncertainty of predictions will pose problems for scientists and government authorities alike.     

On Earthquake Prediction in Japan

Japan’s National Project for Earthquake Prediction has been conducted since 1965 without success. An earthquake prediction should be a short-term prediction based on observable physical phenomena or precursors. The main reason of no success is the failure to capture precursors. Most of the financial resources and manpower of the National Project have been devoted to strengthening the seismographs networks, which are not generally effective for detecting precursors since many of precursors are non-seismic. The precursor research has never been supported appropriately because the project has always been run by a group of seismologists who, in the present author’s view, are mainly interested in securing funds for seismology — on pretense of prediction. After the 1995 Kobe disaster, the project decided to give up short-term prediction and this decision has been further fortified by the 2011 M9 Tohoku Mega-quake. On top of the National Project, there are other government projects, not formally but vaguely related to earthquake prediction, that consume many orders of magnitude more funds. They are also un-interested in short-term prediction. Financially, they are giants and the National Project is a dwarf. Thus, in Japan now, there is practically no support for short-term prediction research. Recently, however, substantial progress has been made in real short-term prediction by scientists of diverse disciplines. Some promising signs are also arising even from cooperation with private sectors.     

Development and present status of seismic evaluation and seismic retrofit of existing reinforced concrete buildings in Japan

This paper describes the development and present status of seismic evaluation and seismic retrofit of existing buildings mainly for low-rise and medium-rise reinforced concrete buildings in Japan. First, since the seismic evaluation of existing buildings has close relationships with the seismic design of new buildings, a brief history of the development of seismic design, seismic evaluation, and seismic retrofit is provided in terms of major earthquake disasters mostly in Japan and associated with some major events in the U.S. Then, the development of seismic evaluation and retrofit is reviewed, focusing on the items in which the author has been deeply involved. This provides insight into previous earthquake damage, methodologies for seismic evaluation, the basic concept of the Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings, studies on the demand criteria for seismic safety, and the present status of seismic evaluation and retrofit. Finally, the typical methods of seismic retrofit and some examples of retrofitted buildings in Japan are explained.     

The diversity of the physics of earthquakes

Earthquakes exhibit diverse characteristics. Most shallow earthquakes are “brittle” in the sense that they excite seismic waves efficiently. However, some earthquakes are slow, as characterized by tsunami earthquakes and even slower events without any obvious seismic radiation. Also, some earthquakes, like the 1994 Bolivian deep earthquake, involved a large amount of fracture and thermal energy and may be more appropriately called a thermal event, rather than an earthquake. Some earthquakes are caused by processes other than faulting, such as landslides. This diversity can be best understood in terms of the difference in the partition of the released potential energy to radiated, fracture, and thermal energies during an earthquake. This approach requires detailed studies on quantification of earthquakes and estimation of various kinds of energies involved in earthquake processes. This paper reviews the progress in this field from historical and personal points of view and discusses its implications for earthquake damage mitigation.     

Hidden Markov models revealing the stress field underlying the earthquake generation

The application of the hidden Markov models (HMMs) is attempted for revealing key features for the earthquake generation which are not accessible to direct observation. Considering that the states of the HMM correspond to levels of the stress field, our objective is to identify these states. The observations are considered after grouping earthquake magnitudes and the cases of different number of states are examined. The problems of HMMs theory are solved and the ensuing HMMs are compared on the basis of Akaike and Bayesian information criteria. A new insight on the evaluation of future seismic hazard is given by calculating the mean number of steps for the first visit to a particular state, along with the respective variance. We further calculate an estimator of the mean number of steps for the first visit to a particular state and we construct its confidence interval. Additionally, a second approach to the problem is followed by assuming a different determination of observations. The HMMs applied to both approaches, contribute significantly to seismic hazard assessment via revealing the number of the stress levels as well as the way in which these levels are associated with certain earthquake occurrence.