全球计算地震学新时代的开始

全球地震学是由观测所推动的一门科学 ,我们学科中较重要的进展大多数可与地震仪器质量的提高和仪器数量的增加联系在一起。简正模式地震学源于 2 0世纪 60年代初期 ,那时 ,加州理工学院 (Caltech)和加利福尼亚大学洛杉矶分校 (U CL A)的地震学家们在 1960年 5月 2 2日智利大地震后记录到的时间序列中获得的波谱中发现了基波超环形模式和球状模式。在 80年代 ,哈佛大学启动了矩心 -矩张量科研项目 ,此外 ,国际加速度检波器部署计划(IDA)和全球数字地震台网 (GDSN )所记录的高质量数据 ,使得全球层析成像成为可能。如今 ,全球地震台网 (…     

第20章：美国对全球数字地震台网的贡献

概述了美国对全球数字化地震台网所做出的贡献，并提供了有关台站安装的一些经验。宽频带数字地震台网联合会（FDSN）负责对全球这项工作进行协调，它的成员包括全球各国负责宽带数字地震仪安装和维护的小组。第81章对宽频带数字地震台网联合会给出了简短概述，有关该联合会的详细情况可以访问其网站：http：//、www.fdsn.org／。任何仅为描述性目的的商业、公司或产品名称的用途不必经美国政府认可。     

全球地震台网超额完成其设计目标

今年，全球地震台网(GSN)已超额完成其以128个台站在世界范围内均匀覆盖地球的设计目标。通过与59个国家的100多个主管机构和地震台网的合作，总共136个GSN台站现已座落在从南极到西伯利亚、从亚马逊盆地到东北太平洋海底的广大地区(图1)。     

中国地震台网、全球地震台网地震目录数据库和震相数据库

地震目录和震相数据在地震学研究中具有重要意义，本文介绍了中国地震台网、全球地震台网地震目录数据库和震相数据库的内容和查询使用方法。     

关于东日本大地震成因的一种观点

2011年3月的日本M9.0大地震使日本科学家的家园惨遭破坏.最近,他们通过梳理地震前的几天内记录到的一大堆杂乱的地震信号,对1000多次新近识别出的地震进行了分类整理.其结果揭示出那条致命的近海断层是如何慢慢滑动,然后突然破裂的.现在看来,那种慢滑行为使断层不断加载,最终达到了破裂点,由此引发了3·11灾难性大地震.     

大地震与地球自转：地幔弛豫的作用

用径向分层的地球模型和可靠的矩张量解,估计了最近２０年中大地震对极移的贡献。和以前仅考虑地球弹性响应引起地震矩释放的分析不同,我们考虑了地幔流变,以及由全球地震活动驱动驱动的与时间相关的震后惯量的改变。我们证明,最近２０年中。全球地震活动没有明显改变地球自转的参数。,我们发现对于最新研究震后应力扩散中贩软流层粘度值,即便在地１０年尺度上,地幔的滞后驰豫也可把平均极移率增大１．２～１．７倍（取决于软     

2007年7～8月全球M≥5.0地震动态

据中国地震局地球物理研究所中国数字地震台网数据管理中心(CDSN DMC)从美国地震学联合研究会数据管理中心(IRIS DMC)得到的最新资料统计,2007年7月全球范围内共发生M≥5.0地震89次.其中M 5～5.5地震发生73次,M 5.6～6.0地震发生13次,M 6.1～7.0地震发生3次,无7级以上地震.最大的一次地震发生在摩鹿加海北部,发震时间为2007年7月26日05时40分16.2000秒,Ms=6.7.本月全球发生的89次M≥5.0地震中有56次发生在东半球,33次发生在西半球.     

2004年8月份全球M≥5.0地震动态

根据中国地震局地球物理研究所中国数字地震台网数据管理中心(CDSNDMC)从美国地震学联合研究会数据管理中心(IRISDMC)得到的最新资料，2004年8月份全球范围内共发生M≥5．0地震91次(见表1)，其中M5—5．5地震69次，M5．6。6．0地震20次，M6.1～6．5地震2次。最大的一次地震发生在智利—阿根廷边界地区，发震时间为2004年8月28日13时4127秒，Mw=6．5。在发生的91次M≥5．0地震中有55次发生在东半球，36次发生在西半球。其地震事件分布图见图1，地震事件目录见表1。     

山西大同数字遥测地震台网中心网络系统集成与资源共享

叙述了山西大同数字遥测地震台网中心网络系统的构成及数据共享的方式,指出用港震系统和泰德系统实现的资源共享方式可满足《数字地震及前兆观测技术规范》所规定的功能要求,运行结果表明该系统行之有效,优点突出。     

Calculating the seismic energy of earthquakes and explosions

An analysis of the Zoeppritz-Wiechert and Golitsyn equations commonly used to calculate the energy of an earthquake showed that these equations are at variance with the physical assumptions made before deriving them. The value of seismic energy as found from the equations currently used for the purpose is overestimated by 1–2 orders of magnitude. It is suggested that the seismic energy of earthquakes can be found from its value over a half-period of the maximum swing.     

Effects of multifocus earthquakes on seismic motion

Earthquakes may cause destruction disproportionate to ground conditions and distance from the epicenter. This paper suggests that disproportionate destruction may be caused by the long duration of the earthquakes. However, to date the mechanism leading to earthquakes of long duration was unknown. On the basis of a detailed analysis of a large number of macroseismic data from historical earthquakes in Armenia, we proposed during 1965–1992 that disproportionate destruction occurred as a result of the spatially separated multifocus character of these earthquakes. A new analysis of instrumental, geodynamic, and engineering-geological data on some typical highly destructive earthquakes that occurred in recent decades shows that the long duration of earthquakes is indeed related to their multifocus character. The destructive effect of the latter occurs irrespective of ground conditions and also at great distances from the epicenters. Seismic movements of long duration have additional impact on constructions, and on seismic instrumnents, as well. It is demonstrated which type of constructions are most vulnerable to long-duration earthquakes and which, on the contrary, are more resistant. We present some recommendations for improvement of the seismic construction code.     

地震活动关联图与新疆的强震

对新疆1970～2002年的地震资料根据不同范围不同震级进行全时空扫描,认为新疆台网监测能力较好地区在绝大多数6级以上地震前,地震活动关联图较为清晰。提出了预警地震的概念,认为预警地震在短临预报方面有一定的前景。     

Predicting earthquakes by analyzing accelerating precursory seismic activity

During 11 sequences of earthquakes that in retrospect can be classed as foreshocks, the accelerating rate at which seismic moment is released follows, at least in part, a simple equation. This equation (1) is ,where is the cumulative sum until time,t, of the square roots of seismic moments of individual foreshocks computed from reported magnitudes;C andn are constants; andt _fis a limiting time at which the rate of seismic moment accumulation becomes infinite. The possible time of a major foreshock or main shock,t _f,is found by the best fit of equation (1), or its integral, to step-like plots of versus time using successive estimates oft _fin linearized regressions until the maximum coefficient of determination,r ²,is obtained. Analyzed examples include sequences preceding earthquakes at Cremasta, Greece, 2/5/66; Haicheng, China 2/4/75; Oaxaca, Mexico, 11/29/78; Petatlan, Mexico, 3/14/79; and Central Chile, 3/3/85. In 29 estimates of main-shock time, made as the sequences developed, the errors in 20 were less than one-half and in 9 less than one tenth the time remaining between the time of the last data used and the main shock. Some precursory sequences, or parts of them, yield no solution. Two sequences appear to include in their first parts the aftershocks of a previous event; plots using the integral of equation (1) show that the sequences are easily separable into aftershock and foreshock segments. Synthetic seismic sequences of shocks at equal time intervals were constructed to follow equation (1), using four values ofn. In each series the resulting distributions of magnitudes closely follow the linear Gutenberg-Richter relation logN=a–bM, and the productn timesb for each series is the same constant. In various forms and for decades, equation (1) has been used successfully to predict failure times of stressed metals and ceramics, landslides in soil and rock slopes, and volcanic eruptions. Results of more recent experiments and theoretical studies on crack propagation, fault mechanics, and acoustic emission can be closely reproduced by equation (1). Rate-process theory and continuum damage mechanics offer leads toward understanding the physical processes.     

全球地震震中数据库及数据格式

全球震中光盘数据库３．０版,向科研单位及所有用户提供地震震中资料。包括地震震中的地理位置,震级大小及震源深度,和发震时间都存贮在光盘地震数据库。通过人机对话方式进行地震数据的存取。     

全球及各地震区带强震活动周期特征

基于地震活动周期谱的Morlet小波分析,确定了全球和13个地震区带的强震活动周期及其置信度.结果显示全球地震活动存在着多个显著稳定的活动周期,而各地震区带除了存在着与全球整体地震活动基本一致的周期外,还存在着特有的活动周期成分.本文研究为探讨全球及区域强震活动趋势及其动力源提供了基础数据.     

利用区域地震记录测定地震辐射能量

地震辐射能量作为描述地震大小的物理量,可为地震应急和灾害评估提供重要参考.现有快速测定地震辐射能量的方法多使用远震记录（35°≤Δ < 80°）,受到几何扩展和频率相关衰减校正方法的限制,利用区域地震记录（5°≤Δ < 35°）测定地震辐射能量的难度较大.因此,本文发展了一种利用区域地震记录快速测定地震辐射能量的方法.研究结果表明：（1）利用该方法可以测定5.0级以上地震的辐射能量,弥补了由于低信噪比和台站分布影响,导致利用远震记录只能稳定测定6.0级以上地震辐射能量的不足;（2）将该方法应用于2009—2021年发生在中国大陆的66次M_W>5.0地震,结果显示74%的单台区域能量震级与远震能量震级的偏差在±0.3以内;对于44次M_W≥5.5地震,区域结果与远震结果基本一致,86%的事件区域能量震级与远震能量震级的差在±0.2之间;（3）结合地震矩资料,得到中国大陆地区地震的能矩比范围为5.2×10^-6~8.1×10^-5,平均能矩比为2.4×10^-5;走滑型地震的平均能矩比高于倾滑型地震,能矩比整体分布存在区域特征,西域地块地震的平均能矩比高于青藏地块东部地震,青藏地块西部地震的平均能矩比最低,同一区域内的地震能矩比也存在差别,这表明不同断层上发生的地震能量释放过程存在明显差异;（4）该方法具有广泛的应用前景,可以在地震台网的日常工作中测定地震辐射能量,为科学研究、地震应急和地震灾害评估提供新的地震参数.

     

Large, moderate, small earthquakes and seismic fortification criterion

IntroductionAccordingtoEarthquakeResistanceandDisasterReductionLawforthePeoplesRepublicofChina,twomethodsareadoptedforseismicdesignoftheconstructionprojectsinChina.Forkeyprojectsandtheprojectseasytocauseserioussecondarydisasters,seismicsafetyevaluationsmustbecarriedout.Andbasedontheresults,seismicfortificationstandardsaredeterminedtomakeseismicdesign.Forgeneralindustrialandcivilbuildings,seismicdesignsarecarriedoutaccordingtotheseismicfortificationstandardsstipulatedbyseismiczonationmap(Ch…     

Variation of human perceptiveness of earthquakes during seismic sequences

This paper describes the variation of the human perception of earthquakes under the peculiar condition of seismic sequence occurrence. To this aim, we chose and have analyzed four seismic sequences that reflect the most common models of seismicity occurrence in the Italian territory. Our data always refer to the epicentral area, so that the contribution of the epicentral distance to the earthquake sensitiveness is considered constant. To search for recurrent behavior of people in the perception of earthquakes, we crossed seismological data to sensitivity data coming from the archives of the Italian Civil Protection. In each sequence, we individuate a number of “indicators”, such as the rate between felt and not-felt events and the minimum magnitude for which 100% of the events are felt. Such indicators are proportional to the energy released by the sequence and can be particularly affected by the time protraction of the sequence, and/or by the different familiarity with the seismic phenomenon, and/or by the intensity of the emotional impact of a seismic crisis. The observed trends of sensitiveness show a significant variation of the people perceptivity within the sequence development. From the analysis of the dataset, one can distinguish the variation of perceptivity due to emotional factors from those due to physical factors. An important observation, which is confirmed by a statistical analysis, is that the source depth does not affect the perceptiveness of earthquakes. Finally, we find important differences between on-sequence and off-sequence human perceptiveness that are connected with the different levels of alert.