利用前兆事件对云南地区地震进行中短期预测研究   总被引：1，自引：0，他引：1       下载免费PDF全文

秦嘉政  钱晓东 《地震学报》2004,26(2):140-150

对某些类型的主震事件, 进行中短期预测也许是可能的. 利用Varnes, Bufe和Varnes提出的破裂时间法模拟前兆地震能量加速释放模型,通过实际观测资料与理论公式的拟合, 可以建立主地震事件的中短期预测技术, 用以确定表示主震的地点、时间和震级大小. 本文使用的是云南区域台网的地震目录资料，覆盖的时间段为1965~2002年. 统计分析表明，在此37年时间内，等于或大于2.5级地震资料是相当完整的. 本文对云南地区的30次主震事件进行了模拟，其中25次主震事件由前兆序列模拟得到的预测时间和震级与实际值相当接近，主震震级预测精度约0.57个震级单位，假定已知前兆序列中最后一次事件，则预测主震发生时间误差约0.64年.对另外的5次主震事件，由于没有足够的前兆事件来充分确定前兆能量加速曲线或是存在对能量加速释放曲线的干扰事件，而不能进行破裂时间法模拟.本文的研究结果还表明，由于云南是破坏性地震和中小地震活跃的地区，因此，主地震与前兆事件最佳搜索半径不存在明显的线性关系.主震矩与系数k，m之间存在强烈的相关性，利用主震地震矩与系数的关系和限制指数m的取值范围，可进一步缩小预测时间和预测震级的最佳拟合区范围，提高了模拟主震事件的预测精度. 本文采用破裂时间法对30次主震事件进行拟合，80％以上获得了较好的结果. 显示出该方法在预测已知主震事件序列的能力方面大有希望，因此，利用前兆事件对未来主震事件进行中短期预测的前景是令人鼓舞的.   相似文献   

GEOLOGICAL MARKS OF A POSSIBLE EXTRATERRESTRIAL IMPACT EVENT ON THE BOUNDARY BETWEEN SINIAN/CAMBRIAN IN TIANMENSHAN IN WESTERN HUNAN     

HUANG Huaiyong  WANG Daojing  CHEN Guanghao  YIN Hanhui 《大地构造与成矿学(英文版)》2004,28(1):43-52

Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.  相似文献   

Field vibration mitigation by honeycomb WIB for pile foundations of a high-speed train viaduct   总被引：5，自引：0，他引：5  

Hirokazu Takemiya   《Soil Dynamics and Earthquake Engineering》2004,24(1):69-87

Environmental vibrations from recent high-speed trains are becoming a special concern in the civil and environmental engineering field since they can give detrimental effects to residents, sensitive equipments and high-tech production facilities in the vicinity of train tacks. Herein, aiming at the vibration mitigation for a specific high-tech industrial area, the low-frequency vibrations from a train viaduct are targeted over an anticipated range. A theoretically designed innovative countermeasure, called honeycomb wave impeding barrier (WIB) for a wave impeding barrier, is introduced and its effects are investigated by computer simulation. The present WIB is based on the wave dispersion phenomenon that can modulate the incoming wavelengths into the shorter wavelengths, creating an apparent wave cut-off characteristic in the wave field across WIB installation area. The shorter wavelengths are further impeded due to the impedance ratio of the WIB walls and in-fill materials and absorbed by the in-fills more. The three-dimensional FEM simulation demonstrates a dramatic reduction effect that is difficult to achieve by conventional measures.  相似文献   

Analysis of parameters of ground vibration produced from bench blasting at a limestone quarry     

Ali Kahriman 《Soil Dynamics and Earthquake Engineering》2004,24(11):887-892

The aim of this study is to predict peak particle velocity level at a limestone quarry located in Istanbul, Turkey. The ground vibration components were measured for 73 blast events during the bench blast optimization studies during a long period. In blasting operations; ANFO (blasting agent), gelatine dynamite (priming) and NONEL detonators (firing) were used as explosives at this site. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured by means of vibration monitors for every event. Then, the data pairs of scaled distance and particle velocity were analyzed. The equation of scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. At the end of statistical evaluations, an empirical relationship with good correlation was established between peak particle velocity and scale distance for this site. The established relationship and the results of the study are presented.  相似文献   

Matuyama-Brunhes reversal and Kamikatsura event on Maui: paleomagnetic directions, Ar/Ar ages and implications     

Robert S. Coe  Brad S. Singer 《Earth and Planetary Science Letters》2004,222(2):667-684

Eighty-nine basaltic lava flows from the northwest wall of Haleakala caldera preserve a concatenated paleomagnetic record of portions of the Matuyama-Brunhes (M-B) reversal and the preceding Kamikatsura event as well as secular variation of the full-polarity reversed and normal geomagnetic field. They provide the most detailed volcanic record to date of the M-B transition. The 24 flows in the transition zone show for the first time transitional virtual geomagnetic poles (VGPs) that move from reverse to normal along the Americas, concluding with an oscillation in the Pacific Ocean to a cluster of VGPs east of New Zealand and back finally to stable polarity in the north polar region. All but one of the 16 Kamikatsura VGPs cluster in central South America. The full-polarity flows, with ⁴⁰Ar/³⁹Ar ages spanning a total of 680 kyr, pass a reversal test and give an average VGP insignificantly different from the rotation axis, with standard deviation consistent with that for other 0-5 Ma lava flows of similar latitude. Precise ⁴⁰Ar/³⁹Ar dating consisting of 31 incremental heating experiments on 12 transitional flows yields weighted mean ages of 775.6±1.9 and 900.3±4.7 ka for the M-B and Kamikatsura transitional flows, respectively. This Matuyama-Brunhes age is ∼16 kyr younger than ages for M-B flows from the Canary Islands, Tahiti and Chile that were dated using exactly the same techniques and standards, suggesting that this polarity transition may have taken considerably longer to complete and been more complex than is generally believed for reversals.  相似文献   

A coherency function model of ground motion at base rock corresponding to strike-slip fault   总被引：2，自引：0，他引：2  

丁海平  刘启方  金星  袁一凡 《地震学报(英文版)》2004,17(1):64-69

IntroductionEarthquakedamagesurveyandresearchresultshavedemonstratedthatspatialdistributiondifferenceofgroundmotionisoneoftheimportantreasonswhichcausedlongstructure(eglongspanbridge,undergroundpipe)destroy.Thathowtoprovideareasonableinputofgroundmotionfieldforaseismicdesignoflongstructureisaurgentprobleminearthquakeengineeringfield.Atpresent,themethodtostudyspatialvariationofgroundmotionsisadoptingstatisticanalysisbasedondensearrayrecordssuchasSMART-1array,etc,togetcoherencyfunctionofground…  相似文献   

An experimental study on seismic responses of multifunctional vibration‐absorption reinforced concrete megaframe structures     

Zongjian Lan  Yuji Tian  Liang Fang  Shuting Liang  Xinde Wang 《地震工程与结构动力学》2004,33(1):1-14

Two models are tested on a shake‐table. One of the models is a normal reinforced concrete megaframe structure and the other is a multifunctional vibration‐absorption reinforced concrete megaframe structure in which the laminated rubber bearings are placed between the major frame and the minor frames. Two earthquake motions (the El Centro wave and the Taft wave) are used during the test. This paper presents the dynamic characteristic, the seismic responses and the failure mechanism of these two models under varying peak acceleration levels for each of the earthquake motions. The test results demonstrate that the aseismic behavior of a multifunctional vibration‐absorption reinforced concrete megaframe structure is much better than that of a normal reinforced concrete megaframe structure. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Dynamic performance of twin curved cable‐stayed bridges     

C. Gentile  F. Martinez y Cabrera 《地震工程与结构动力学》2004,33(1):15-34

The dynamic behaviour of two curved cable‐stayed bridges, recently constructed in northern Italy, has been investigated by full‐scale testing and theoretical models. Two different excitation techniques were employed in the dynamic tests: traffic‐induced ambient vibrations and free vibrations. Since the modal behaviour identified from the two types of test are very well correlated and a greater number of normal modes was detected during ambient vibration tests, the validity of the ambient vibration survey is assessed in view of future monitoring. For both bridges, 11 vibration modes were identified in the frequency range of 0ndash;10Hz, being a one‐to‐one correspondence between the observed modes of the two bridges. Successively, the information obtained from the field tests was used to validate and improve 3D finite elements so that the dynamic performance of the two systems were assessed and compared based on both the experimental results and the updated theoretical models. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Period formulas of shear wall buildings with flexible bases     

Faouzi Ghrib  Haji Mamedov 《地震工程与结构动力学》2004,33(3):295-314

The evaluation of the fundamental period of shear wall buildings considering the flexibility of the base is investigated in this paper. This research is motivated by the discrepancy reported between the formulas used in different building codes and the measurement of real buildings. Both experimental and analytical approaches are used to assess the effect of the base flexibility on the fundamental period of shear wall structures. In total, twenty buildings built on different types of soil are tested under ambient vibration. The fundamental period is identified using a non‐parametric linear model in the frequency domain. The results show that fundamental period formulas used by UBC‐97 and NBCC‐95 are inadequate since they do not include the effect of the foundation stiffness. To improve the estimation of the fundamental period of shear wall buildings, an analytical approach is presented. The structure and the foundation are represented by a continuous‐discrete system. The stiffnesses of the base are represented by translational and rotational discrete springs. The rigidities of these springs are evaluated from the elastic uniform compression of the soil mass and the size of the foundation. The analytical predictions improve the estimation of the fundamental period and keep the computation simple. The error between the measured period and the analytical results is, on average, less than 10%. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

ENSO事件与鲁西北夏季降水的关系     

于凤英  张国胜 《山东气象》2004,24(1):13-15

应用近百年ENSO事件的研究成果和ENSO事件影响年的资料，统计分析近50年来ENSO事件与鲁西北夏季降水关系，为短期气候预测和汛期气象服务提供参考依据。  相似文献