以ISCloc为核心方法和技术,ISC统一分析处理全球的观测数据并定期出版地震观测报告.从资料收集、数据关联、定位方法和技术、数据分析与出版4个方面阐述ISC观测报告产出的主要过程.2008年后,ISC每年汇集300000—500000次以上地震,其中约20％的地震需要地震学家分析和审核,观测报告发布、出版时间比实际地震发生时间滞后约24个月.

ISC-GEM地震目录是ISC发布和管理的一份全新的、基于仪器记录的全球中强震地震目录,于2013年首次发布.截至2018年2月,该目录从1900-2014年,跨越115年的时间尺度,共计28000余条地震,其中中国陆地区域的地震近千条.ISC-GEM地震目录的产出过程中,收集了1900年以后共百余年的观测数据,截至2018年6月,可用的地震波到时数据达20000000余条,振幅数据达6000000余条.目录中的所有地震经过两步法重新定位:EHB方法确定震源深度,ISCloc修定震中和发震时间.矩震级是唯一的震级标度,采用直接计算或由其他震级(Ms和mb)转换的方式而获得.

The records of 168 global seismographic stations from 2 to 3 o'clock (UTC) on April 1,1936 have been collected in order to locate the strong earthquake M63/4 occurred in northeast Lingshan of Guangxi.The station readings were grouped and associated based on the macro-epicenter of Lingshan mainshock (22.5°N,109.4°E) and the initial P wave residuals of the seismic stations.Finally records of thirteen stations were successfully associated to Lingshan mainshock,and phase arrivals of 7-8 stations contributed to the event relocation.The routine location method and model of China National Seismic Network Center and ISCloc have been used to relocate the Lingshan mainshock,and the relocation results show that the distance between the two relocated epicenters is about 47.6 km.By comparison,the routine location method and model of China National Seismic Network Center are more suitable for the data with the poor observational conditions of Lingshan mainshock.

" Rebuild of the ISC bulletin (1964-2010)" is an important project which is being undertaken by ISC.The main method and technique adopted in the project is the new ISC locator (ISCloc) which includes four features:uses all reported phases with a valid ak135 travel time prediction;obtains an initial guess for the hypocentre using the Neighbourhood Algorithm;takes into account the correlated travel time prediction errors in a linearized iterative least squares location algorithm;meets some conditions before getting a free-depth solution.ISCloc relocated more than 1100 000 global events which were reviewed by ISC before,and 180 000-200 000 events needed for major manual analysis and edit are choosen out based on some criteria of the original times,epicenters,residusals of phase arrivals and focal depths.The analysis and edit of the events in 1960s have been finished at the end of 2015,but it probably will be waited to the year 2019-2020 for the review of all events needed.

本文收集了1936年4月1日2时至3时（UTC）全球168个台站的仪器记录,根据1936年4月1日广西灵山县东北部M6地震的宏观震中（22.5°N,109.4°E）和计算所得各台站初至P波的到时残差,将168个台站的数据与灵山主震进行关联或相关性分析.最终有13个台站的数据与灵山主震关联成功,其中7—8个台站的到时数据参与了定位计算.分别利用我国国家测震台网的常规定位方法和技术以及ISC的定位方法和技术对灵山主震进行重新定位,两种重定位方法得到的灵山主震震中相距47.6km,经过比较,我国国家测震台网的定位方法和技术更适合灵山主震的数据特点.

The location parameters of the Zayu, Tibet M8. 6 earthquake sequence in 1950 in the published catalogues are poor, which cannot help further study of this great event. In order to provide more precise location results and some features of their spatial-temporal distributions, and to reveal the stress field in the corresponding region, we attempted to relocate this earthquake sequence and to determine the focal mechanisms. The data of global seismic stations from International Seismological Summary (ISS) and the Catalogue of China Earthquakes (BC 1831-AD 1969) were collected. The 16 events with M >= 6 of the Zayu, Tibet M8. 6 sequence were relocated by P arrivals at 239 worldwide stations using the routine location method and model of Chinese National Seismographic Network: Improved Geiger and the JB time tables. The corresponding fault plane solutions and composite fault plane solutions were determined by first motions of P waves based on the new relocations. (1) The relocations of 16 strong earthquakes of the Zayu M8. 6 sequence have been completed. It is shown that the epicenters in different periods appeared in different sub-regions: A foreshock which occurred on 23 Feb 1950 appeared in the 1st sub-region, the top of the great bend of the Yarlung Zangbo River, which lies at the north of Motuo. The mainshock and the following 7 aftershocks in 3 days which occurred from 15 Aug 1950 to 18 Aug 1950 were located in the 2st sub-region near Zayu and distributed along the north-west belt. The 3 aftershocks in period 3 which occurred from 22 Aug 1950 to 13 Sep 1950, were located in the 3st sub-region extending to the south, India and Myanmar. The 3 aftershocks in period 4 which occurred from 30 Sep 1950 to 15 Apr 1951 appeared in the 4st sub-region at Motuo and Cuona, west of the aftershock epicenter area. Another aftershock occurred on the 110th day after the mainshock, the epicenter of which returned to the place near the mainshock. (2) The focal mechanism solutions determined based on the relocations indicate that the NWW strike of a nodal plane of the mainshock is consistent with the NWW direction of the major axis of the aftershock epicenter area in the 2st sub-region. All compressive axes P and tensional axes T of the earthquake sequence are nearly horizontal, of which most dip angles are less than 20 degrees. The compressive axes of the mainshock and the aftershocks in the 2st sub-region are nearly north-south direction, and tension axes are nearly east-west direction. But in the 3st and 4st sub-region, the compressive axes of aftershocks are-nearly east-west direction, and tensional axes are nearly north-south direction. The 16 events of the Zayu, Tibet M8. 6 earthquake sequence in 1950 have been relocated. The new results are quite different from the parameters in the previous catalogues of which the locations of many aftershocks were exactly the same as the mainshock, i. e. only one point. The relocations indicate that the epicenters in different periods appeared in 4 different sub-regions rather than distributing along the determined rupture. The obvious correlation of these 4 sub-regions is clockwise rotation movement. The focal mechanism solutions determined based on the relocations display that the differences of focal mechanisms among the aftershocks of the sequence are large.

1950年8月15日西藏察隅发生M8.6巨大地震.我们利用收集到的全球239个台站的P波资料,利用我国国家测震台网的常规定位方法和模型,对察隅M8.6强震序列进行了重新定位,并在此基础上重新计算了震源机制解.重定位后的结果表明,察隅M8.6强震序列显示出不同时段的震中分区分布特征:第1阶段是前震,1950年2月23日在墨脱北部雅鲁藏布江大拐弯的顶部发生;第2阶段是1950年8月15日-1950年8月18日,发生主震和之后3天内的余震,都分布在察隅附近,并且这些震中呈北西条带分布;第3阶段的余震是1950年8月22日—1950年9月13日,它们扩展到南部的印度和缅甸地区;第4阶段的余震是1950年9月30日-1951年4月15日,发生在西部的墨脱、错那等地.这四个分区的关联特点为顺时针旋移.重新计算后的震源机制解显示出:主震的NWW走向的节面与主震后2区内余震震中的NWW分布方向一致;序列中所有的压应力轴P和张应力轴T,都接近于水平向,其倾伏角大都小于20°;察隅主震和2区内余震的压应力轴P为近南北向,张应力轴T为近东西向;但3区和4区余震的P轴为近东西向,T轴为近南北向.反映出该强震序列中余震震源机制解的差异比较大.

A big earthquake with M7 .7 was occurred in the southeast of Lang county in Tibet on July 29,1947.We collect the global observational phase readings of this event,and we re-determined the source parameters with the daily location method and technical of the Chinese national network and the ISC locator respectively.Both the relocated epicenters are at the near of Lilong rupture,we prefer the location results of the Chinese national network after our comparison and analysis,and we recalculated the focal mechanism based on this new results.It is consistent with the strike of Lilong rupture,the revised location is also at the Lilong rupture,this indicate that the Lilong rupture was probably the seismogenic fault.

1950年8月15日西藏发生8 6级巨大地震.经重新测定这次巨震序列的震源参数,推断出西藏察隅M8.6主震的震源断层,结合余震分布、极震区分布、震源机制、地震条带和活动断层相互验证了震源断层的科学合理性.

简介国际地震中心(ISC)的发展历史、主要任务、人员组成和出版物.对ISC出版的地震观测报告<Bulletin of the International Seismological Centre>,详细阐述其数据汇总和分析流程.

Comparison of the seismic sequences between Tonghai earthquake in 1970 and the Tangshan earthquake in 1976 indicates that the attenuation,number,intensity of aftershocks and shape of epicenter areas were different.In this paper,an interpretation is proposed that aftershocks reflect the adjustment process of the medium in seismic source after severe fracture.If the radio(a/b)from major axis length a and minor axis length b of the aftershock epicenter area is large,it implies the source volume being near to a plane and the adjustment process at the plane should be simple,so the aftershock attenuation is faster and strong aftershocks are less.In opposite case,with small a/b,the source volume is near to a cubic and the adjustment process is more complicated,so the aftershock attenuation is slower and strong aftershocks are more and stronger.It can be attempted to use the parameter a/b to estimate quickly that it the stronger aftershocks will be more or not,and the aftershock attenuation will be slow or not for the case that the aftershocks can be located immediately after the mainshock.

Based on the early bulletins of seismological observation, the parameters of 1918 Nan’ao MS7.3 earthquake and its two strong aftershocks are revised by using current locating theory and method of seismology. According to the results, the earthquake epicenter should be nearby the Nanpeng Island which has small earthquake cluster and active tectonics background of strong earthquakes.

概述了用我国数字化地震台网的资料测定的各种震级标度及相关问题.同时阐明矩震级标度Mw的优势和良好的应用前景.建议今后我国观测报告中给出新参数Mw.

介绍了2001年以来地震台站的资料分析情况和国家数字地震台网分中心的资料产出情况,通过分析表明,由于宽频带数字地震资料具有频带宽、动态范围大等特点,2003年利用数字地震台网资料分析地震的数量比传统的模拟记录提高30%～4O%.

加速度随距离的衰减关系,对于抗震设计是重要的.一次大地震破坏严重的地区一般在几十千米的范围内,因此,近场衰减关系研究就更重要.美国、日本和我国台湾的几次地震的地面运动资料比较充足,较之远场而言,近场衰减的研究则相当薄弱.

Two improvement measures pointed to the past error to calculate b ‐values have been proposed: (1) adopt seismic moment magnitude M W which is the uniform absolute magnitude scale; (2) discard the magnitude point in which some earthquakes are missing, then compute the b ‐value using least square method to fit the data. Therefore b ‐value is more accurate. The b ‐values all approach to 1.0 for three sets of various precision and sources. The earthquake occurrence periods of great earthquakes for coming 50~100 year (extend 1~2 magnitude) have been computed using 13 years recent earthquake observation data and fix b =0.85. The results demonstrate that the earthquake occurrence periods with magnitude greater and equal to 6 and 7 are well consistent with that which are calculated from the data of 100 years historical earthquakes. So, the extension is reliable.

Two improvements measurements pointed to the errors to calculating b values have been proposed: ( 1) to adopt the uniform absolute magnitude scale, seismic moment magnitude M-W, (2) to discard the magnitude points for which the earthquakes absent and lose, and then to compute the b value using least square method to fit the data. The b values obtained for three data sets of different precision and sources are close to 1.0. The occurrence periods of great earthquakes for coming 50 similar to 100 year (extend 1 similar to 2 magnitude) have been computed using 13 years recent earthquake observation data and fix b = 0.85. The results demonstrate that the earthquake occurrence periods with magnitude greater than and equal to 7 and 8 are well consistent with that calculated from the data of 100 years history earthquakes, implying the reliable extension.

提出了一种估计一个地区平均构造剪应力值的方法.用这种方法,选取哈佛大学公布的1977～1999年共15 993次地震的矩张量数据,估计了美国西部19个地区、中国和邻区43个地区(每个地区为10(×10(范围)的平均环境剪应力值.结果表明,美国西部南加州西部海域和南加州应力最高,达13.7和12.0 MPa,然后向北、向南和向东逐渐递减,但最小也达8.7 MPa,是最高值的63%.中国新疆西北部地区和西藏察隅地区应力水平最高,达17.2和12.9 MPa,比美国高.中国的华北、云南、四川、台湾和美国南加州的应力水平差不多.中国南北地震带的应力水平为13 MPa左右,比南加州略高.两个重要地区的平均剪应力值分布图,提供了地学的基本数据.这些结果可为研究地震活动的大背景提供依据,对研究强地面运动参数(如峰值加速度及反应谱等)的衰减关系也是有用的.

针对我国地震工作的实际需要,从1995年起,<中国地震台网目录和地震矩张量解>(原<中国地震台网观测报告>)刊登了国内较大地震(MS≥5.5)和全球大震(MS≥6.0)的地震矩张量解和震源机制解.同时在<中国地震年报>上也刊登国内及邻区较大地震的地震矩张量解和震源机制解.为了方便用户使用,本文对有关参数进行了说明.

We have found from the fracture mechanics rupture model of earthquakes that the peak ground acceleration PGA and velocity PGV and displacement PGD strongly depend on the tectonic ambient shear stress value τ0．τ0 value is introduced into the predictive equation of PGD by us, at the same time the dependence of predominant frequency of PGD fd on magnitude is considered. Based on both improvements, the predictive equation of PGD (CLB98d) has been derived from theoretical analysis. It has been tested by observahon data that this predichve equahonit is sintable for epicentral distance range △=10-250km and magnitude range Mw = 4-7.2. There are different To values in different regions all over the world, but the influence of τ0 value on PGD is not large.