Comparison between earthquake magni-tudes determined by China seismograph network and US seismograph network (II): Surface wave magnitude     

刘瑞丰  陈运泰  Peter Bormann  任枭  侯建民  邹立晔  杨辉 《地震学报(英文版)》2006,(1)

Introduction Earthquake magnitude is the most common measure of an earthquake′s size,and is one of the basic parameters of an earthquake.There are three most familiar scales of earthquake magnitude:ML(local earthquake magnitude),MS(surface wave magnitude)and mB/mb(body wave magni-tude).Richter(1935)introduced ML when studying earthquakes in Southern California.In1945,Gutenberg(1945a)put forward surface wave magnitude scale to determine earthquake magnitude(MS)using surface waves(20s)of s…  相似文献   

Seismic quantification of the explosions that destroyed the dome of Volcán de Colima, Mexico, in July–August 2003     

Vyacheslav M. Zobin  Carlos J. Navarro-Ochoa  Gabriel A. Reyes-Dávila 《Bulletin of Volcanology》2006,69(2):141-147

In July–August 2003, the andesitic lava dome at Volcán de Colima, México, was destroyed by a sequence of explosions that replaced the 2×10⁶ m³ dome with a crater 200 m across and 30 m deep. The two strongest explosions occurred on July 17 and August 28. The initial low-frequency impulses that they produced, which were recorded on broadband seismic records, allowed an estimation of the counter forces of the initiating process as being equal to 0.3×10¹¹ N and 1×10¹¹ N for the July and August events, respectively. The seismic characteristics follow the Nishimura-Hamaguchi scaling law for volcanic explosions, reflecting self-similarity in the processes initiating explosive events. The results also show that counter forces can discriminate between the sizes of explosive eruptions that are assigned the same magnitude by conventional methods of classification such as the Volcanic Explosivity Index. The increasing use of broadband seismometers may therefore provide the basis for using counter forces to determine the magnitude of explosive eruptions.  相似文献   

Seismic hazard of the Eastern Mediterranean     

Amr Z. Hamouda 《Acta Geophysica》2006,54(2):165-176

Earthquake hazard parameters such as maximum magnitude, annual mean seismic activity rate, and the Gutenberg-Richter parameter, have been evaluated for the Hellenic and Cyprean Arc regions of the Eastern Mediterranean. The applied maximum likelihood procedure permits the combination of both historical and instrumental data. The collected data from different sources cover earthquakes with magnitude ≥ 3.5 throughout the last two centuries. The historical part of the catalogue only contains the strongest events, whereas the complete part can be divided into several subcatalogues, each assumed complete above a specific threshold of magnitude. The hazard parameters assessment is performed for the two study regions. The Hellenic Arc region was found to be of higher seismicity level than the Cyprean Arc region. The number of annually expected earthquakes with magnitude ≥ 3.5 is much larger in the Hellenic Arc (56±2) than in the Cyprean Arc (35±2). The maximum magnitude calculated in the Hellenic Arc zone is 7.8±0.4 for the time period equal to the length of the catalogue, i.e., 210 years. For the Cyprean Arc zone, the maximum possible magnitude is 6.8±0.4 for the time span of 330 years.  相似文献   

M L Determination for Local and Regional Events Using a Sparse Network in Southwestern Germany     

Stefan Stange 《Journal of Seismology》2006,10(2):247-257

A method for the determination of consistent local magnitude M _L values (Richter scale, or M _WA) for earthquakes with epicentral distances ranging from 10 km through 1000 km is demonstrated. The raw data consists of nearly 1300 amplitude readings from a network of six digital seismographs in Baden–Württemberg (Southwestern Germany) during 26 months starting in 1995, later extended by another 1000 amplitude readings until 1999. Relying on most of the basics introduced by C.F. Richter a three-parameter attenuation curve (distance correction, magnitude-distance relation) for Baden–Württemberg and adjacent areas is presented. Station corrections are evaluated and the attenuation curve is calibrated with respect to other agencies for distances greater than 650 km. Reasonable parametrisations are discussed and meaningful error bars are attributed. Finally, a seventh station is incorporated by means of its station correction alone, without needing to update the attenuation curve.  相似文献   

查表法设计华北地区最大震级时间序列模糊预测系统     

武安绪  林向东  张洪魁  徐平  鲁亚军  穆会泳  李菊珍  乔振瑛  丁晗 《东北地震研究》2006,22(1):11-17

本文介绍了查表法设计模糊系统(FSLE)的方法与原理,然后基于该方法建立了华北地区及主要地震带最大震级时间序列的预测模型,并进行了预测内符检验。分析认为,该方法的建模与预测精度较高,模型外推泛化能力较强,原理简单直观,计算结果稳健。因此,FSLE方法可作为地震趋势建模与预测分析工作中的一种有效工具。  相似文献   

河北文安5.5级地震前天津地区流体短期前兆异常分析     

庞群英  岳秀侠  马君钊 《山西地震》2007,(2):4-6

以河北文安5.5级地震为例,分析了地震前天津地区流体测项的异常变化。结果表明,天津王3井、王4井水汞、潘庄井及双桥1井水位在震前都出现了明显的短期前兆异常。  相似文献   

不同标度震级关系和台基影响问题探讨   总被引：2，自引：1，他引：2  

张宏志  刁桂苓  赵明淳  王勤彩  张骁  黄媛 《中国地震》2007,23(2):141-146

利用近年中国数字地震台网观测报告中的中国及邻区地震目录资料,取能够同时计算面波震级MS和近震震级ML的地震,拟合出2种震级之间的关系,发现与过去使用30余年的换算公式存在系统差别。考虑现代化地震数字观测系统有动态范围大、频带宽、台站多、覆盖区域广、测定精度高的特点,由此拟合的关系应当更可靠。考虑不同误差因素统计面波震级MS和近震震级ML的关系表明,2种震级之间换算和不换算的差别并不大,因此建议MS和ML震级之间不换算为宜。分析地震台站的场地响应发现:一些基岩台的放大因子在1附近,场地响应不随频率变化;处于沉积土层的台站,放大因子在低频段大于1,高频段小于1;还有一些台站在某个频段范围大于1,或者小于1。另外,沉积土层台站的单台震级和台网平均震级差也随周期增大,呈现由负到正的增长趋势。看来并不存在固定的台站校正系数,因此不能把台站校正作为提高震级测定精度的方法。  相似文献   

Nonlinear magnitude frequency relation and two types of seismicity systems     

Shi-Jun Chen  Zhi-Cai Wang  Jiu-Qing Tao 《地震学报(英文版)》1998,11(2):207-218

A nonlinear magnitude frequency equation has been derived in this paper on the assumption that all seismicity systems hold fractal characteristics, and according to the differences of relevant coefficients in the equation, seismicity systems are classified into two types: type I, the whole earthquake activity is controlled by only one great unified system; type II, the whole earthquake activity is controlled by more than one great system. One type of seismicity system may convert to the other type, generally. For example, a type I system will change to a type II system prior to the occurrence of a strong earthquake in North China. This change can be regarded as an index for earthquake trend estimation. In addition, the difference between b value in nonlinear magnitude frequency equation and that in linear equation and the term dΔM related to the coefficients of nonlinear terms obtained in this paper are proved to be a pair of available parameters for medium short term earthquake prediction.  相似文献   

九江台震级偏差讨论与校正     

李道叶 《地震地磁观测与研究》1998,19(1):51-57

通过选取大量震例,分析了九江台所产生的震级偏差的可能原因,并提出了校正意见。  相似文献   

二滩水电站地震遥测台网持续时间震级的研制   总被引：2，自引：0，他引：2  

赵珠  谢蓉华 《地震地磁观测与研究》1998,19(2):21-29

利用二滩水电站地震遥测台网的速度量和位移量观测记录,收集了震级ＭＬ为０．４￣５．４的４６０次地震（Δ〈２１０ｋｍ）的振动持续时间３５００多条,制作了该台网的持续时间震级公式和便查表。在方法上,不同于通常的按一次或两次曲线拟合,而采取计算机自动分段按折线拟合的方法,以阻尼最小二乘法完成其计算;在资料上,先分台制作８个子台的持续时间震级公式,在此基础上选择仪器、台基及公式中参数相近的子台,制作了适用于  相似文献