用云南滇西地区的地震烈度资料估算短周期波的区域性衰减特征

本文用云南滇西地区的历史和现代破坏性地震的烈度分布资料,估算了短周期波的区域性衰减率γ和地区Q_I值,把研究区分为五个小区进行讨论,采用联合测定法给出了滇西五个小区域内的平均Q_I分布。结果表明,滇西地区的平均Q_I值在40—180之间,其中尤以盐源—宁蒗地震区和剑川—大理地震带的平均Q_I值最低。分别为40和60左右。一个重要的现象是低Q_I地区对应破坏性地震发生比较频繁的地区,由地震活动重复周期及Q_Z值分布的结果分析,上述两个地震带区将是发生M_S=6.0—7.0左右的潜在震源危险区。其次,由Ⅴ度和Ⅵ度的烈度衰减半径R_i与震级M_S的关系,统计结果给出M_S=1.34logR_Ⅴ(km)+3.83;或M_S=1.28logR_Ⅵ(km)+4.42。     

用烈度衰减的椭圆模型标度华北地区历史地震震级

本文用1913年至1981年华北地区29次地震的171组烈度线资料,进行回归统计,求出烈度衰减公式为I=e~1.511+0.192Ms(a~2+h~2)~(-0.112)I=e~1.486+0.193Ms(b~2+h~2)~(-0.116)依此可以根据地震历史资料确定的不同烈度区的长轴半径(a)、短轴半径(b)的长度(km),结合该地区的正常震源深度(h)标度历史地震的震级.用近代仪器测定的100次地震震级,检验以烈度衰减公式标度的震级,其相关系数为0.97,而标准离差仅为0.22级.本文对华北地区明清时期的46次历史地震震级作了重新标度.     

澜沧-耿马地震后尾波衰减的区域特征

本文在地方震尾波单次散射模式的基础上,用澜沧-耿马 Ms=7.6和7.2两次强震后,震中附近4个短周期台站记录的余震尾波观测资料,采用一种新的联合测定法估算了澜沧-耿马地区尾波振幅衰减率和Qc值.结果表明,在所划分的南区和北区内,尾波振幅衰减率发生了明显的区域差异,表现为南区衰减快(Qc=114),北区衰减慢(Qc=231),并讨论了这种空间差异的原因.本文的结果还给出,尾波源因子 A0(f)与地震矩和震级有较好的线性关系,用地震定标律导出:lgM0=lgA0(f)+17.6,MD+0.67lgA0(f)+1.21,lgM0+1.5MD+15.79.其次,用尾波单次散射模式和多重散射模式计算了振幅衰减率s 和m,结果给出两种模式结果之比m/s 在1.20-1.50之间.用区分固有 Q 和散射 Q 的关系求出了南区和北区的 S 波散射平均自由程 L 分别为54km和122km,由此证实了低 Q 地区对应强散射.     

用位错模型研究震级与烈度的关系

作者根据位错模型导出了震级不仅与震中烈度和震源深度有关,而且与极震区面积有关。震中烈度通过应力降和震级联系起来,而极震区面积则通过位错面的面积或震源体积和震级联系起来,使震级与烈度的物理联系更加明确。 用我国的61个浅源地震资料,用逐步回归方法计算出震级M与震中烈度I0、极震区面积（面积单位为平方公里）A0的关系为: M=3.53+0.039I02+0.0178（Ig A0）3,还分别计算出震级与6—8度区面积A6、A7、A8的关系为: M=3.63+0.72 Ig A6,M=5.34+0.718（Ig A7）·（IgIg A7）,M=5.92+0.104（Ig A8）2。并外推出震级与5度区面积A5的关系为: M=3.03+0.72 Ig A5。 利用这些关系式来确定历史地震震级比仅考虑震中烈度来确定有较好的效果。     

用地震波的持续时间测定川滇地区的近震震级

本文用云南,四川地区的大量地震资料讨论了地震尾波衰减,维式地震仪器静态放大倍数以及震中距与地震波持续时间的关系.求得了川滇地区垂直向和水平向的地震波持续时间tDU测定近震震级的公式:MDZ=0.94+1.57log(tDUV)+0.00136△(1)MDM=0.78+1.60log(tDUM)+0.00114△(2)结果表明,用持续时间 tDU求得的震级标准误差比用振幅求得的震级标准误差要小.说明用这种方法求近震震级也许是较好的方法.      

云南地震烈度随距离的衰减规律

本文利用云南地区1900年以来发生的震中烈度等于或大于Ⅵ度的48个地震等烈度线,用最小二乘法分别求得了四个地震带和三个地震区以及整个云南的烈度衰减关系。当已知潜在震源时,可以为估计某一场地由一次大地震所造成的最大可能烈度和地震危险性提供一些依据。 文中根据统计结果分析比较了不同方向和不同地区的烈度衰减特征,表明烈度衰减规律具有明显的方向性和地区性。因此认为,区分不同地区建立各自相对独立的烈度衰减关系是有实际意义的。 最后,对统计分析中的某些问题也作了初步讨论。     

全球大震和中国及邻区中强震地震活动(2011年9-10月)

本目录中的地震参数来自"中国地震台站观测报告"(简称"月报").其中,国内及邻区给出M≥4.7的事件,全球给出M≥6.0的事件、"月报"由中国地震台网中心按月做出.本目录中的发震时刻采用协调世界时(UTC);为了方便中国读者,也给出北京时(BTC).震中位置除给出经纬度外,还给出参考地区名,它仅用作查阅参考,不包含任何政治意义;还给出测定震源位置的台数(n)和标准偏差(SD).面波震级Ms是对中周期宽频带SK地震仪记录,采用北京台1965年面波震级公式Ms=lg(AH/T)+1.66 lg(△) +3.5(1°＜△＜130°)求得.AH是两水平分向最大面波位移的矢量合成位移.Ms7是对763长周期地震仪记录,采用国际上推荐的面波震级公式Ms7 =lg(Av/T)+1.66 lg(△)+3.3(20°＜△＜160°)求得.Av是垂直向面波最大地动位移.mb是短周期体波震级,ML是近震震级.为避免混乱,震级之间一律不换算.为方便读者,还给出美国NEIC定出的面波震级Msz和短周期体波震级mb.     

用位错模型研究震级与烈度的关系

作者根据位错模型导出了震级不仅与震中烈度和震源深度有关,而且与极震区面积有关。震中烈度通过应力降和震级联系起来,而极震区面积则通过位错面的面积或震源体积和震级联系起来,使震级与烈度的物理联系更加明确。 用我国的61个浅源地震资料,用逐步回归方法计算出震级M与震中烈度I₀、极震区面积（面积单位为平方公里）A₀的关系为: M=3.53+0.039I₀²+0.0178（Ig A₀）³,还分别计算出震级与6-8度区面积A₆、A₇、A₈的关系为: M=3.63+0.72 Ig A₆, M=5.34+0.718（Ig A₇）·（IgIg A₇）, M=5.92+0.104（Ig A₈）²。并外推出震级与5度区面积A₅的关系为: M=3.03+0.72 Ig A₅。 利用这些关系式来确定历史地震震级比仅考虑震中烈度来确定有较好的效果。     

云南地区区域剪切应力值及其对地震危险性的估计

本文利用SK地震仪器记录的中小地震的P波初动半周期资料,测定了云南地区区域剪应力值τ_0。根据剪应力值随时间变化和空间分布特特征,讨论了云南各地震带、区的地震活动趋势。结合小震P轴变化特征以及τ_0值强度分布图象,分析结果表明,最近几年内云南地区不会发生7.0级以上的大震,但四个应力值较高的地震带、区发生5.0—6.0级左右的中强震的可能性较大,是需要进一步加强监视的地震危险区。 其次,讨论了该区震源参数与面波震级M_S之间的经验统计关系。     

震源深度对烈度衰减关系模型的影响

收集整理1970年以来我国大陆地区418次M_S≥4.0地震的烈度等震线和震源深度资料,将我国大陆地区划分为西部(西南和西北地区)和东部(东北、华北地区和华中、华南地区)地区,采用最小二乘法,根据Estevad等和卢建旗等的研究,分区建立基于震源深度的2种烈度衰减关系经验统计模型,探讨震源深度对烈度衰减关系模型的影响。分析发现,东部地区Ⅵ度(6度)区和西部地区Ⅶ度(7度)区长、短轴半径的影响结果略有不同。选取2008年以来M_S≥5.0地震事件,取6度以上地区地震烈度圈数据,以实际烈度与经验统计模型烈度的比值为指标,验证2种经验统计模型与实际烈度评定结果的吻合程度,结果表明：2种经验统计模型所得烈度变化趋势基本一致,且基于模型的预测烈度值与实际烈度值较为一致。将2种烈度衰减关系经验统计模型与传统椭圆烈度衰减关系模型进行比较,发现经验统计模型更精准。分析认为,2种基于震源深度的烈度衰减关系模型在我国东、西部地区的适用范围参数如下：(1)西部地区：震级为4.0≤M_S≤8.6,震中距为0≤R≤486 km,震源深度为3 km≤H≤...     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Earthquake Engineering and Engineering Vibration Aims And Scope

正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and     

Foreword

Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States.     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Enhancing remote sensing research on global change to improve our understanding on Earth system processes

正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases     

Solute concentrations in the lower niger river and the source rock contribution

Water quality analyses for the Niger River for the 1980/81 hydrological year are presented. The samples were collected from the main river at Lokoja, and from two main tributaries, the Kaduna and the Benue Rivers. Different water types were distinguished by the concentrations of major ions. The type Ca > Na > Mg > K - HCO₃ > SO₄ > Cl was represented at all stations during at least part of the year. Chloride was found to dominate the sulphate ion in the Kaduna and Niger, while the Benue maintained a higher concentration of sulphate relative to chloride all year round. Distinct patterns of seasonal variation in the ion concentrations were observed, particularly for the samples collected at Lokoja. Low ion concentrations were prominent during periods of high discharge, while low flow periods coincided with high dissolved ion concentrations. The contribution of rainwater to the total dissolved solids in the river waters was assessed indirectly using rainwater chemistry data from the Gulf of Guinea. The estimated rainwater contribution to the Lower Niger amounts to 5.15 mg 1^?1. Geochemical weathering calculations involving reactions of the four major minerals of granitic rocks - anorthite, biotite, albite, and K-feldspar - with carbon dioxide and water, can account for the average water composition of the Lower Niger. The proportion of the ionic components was also related to the occurrence of the respective element in the minerals.