共查询到19条相似文献，搜索用时 412 毫秒
1.
On the basis of the absolute and relative gravity observations in North China, spatial dynamic variation of regional gravity fields is obtained. A multi-scale decomposition technique is used to separate anomalies at different depths, and give some explanation to gravity variation at different time space scales. Gravity variation trends in North China are improved. Based on this result and the analysis of wavelet power spectrum, the images of the depth of wavelet approximation and detail are obtained. The results obtained are of scientific significance for the deep understanding of potential seismic risk in North China from gravity variations in different time space scales. 相似文献
2.
Introduction For a long time, the seismologists have paid great attentions to the research on the spatio- temporal distribution of earthquake intensity, which provide us with significant information for the researches on crustal stress variation, tectonic activity and earthquake risk prediction in a certain spatio-temporal region. The existing results have shown consistently that the intensity of earth- quakes is characterized by non-stability, non-linearity in temporal domain and non-uniformi… 相似文献
3.
Geng Lumin Zhang Guomin Shi YaolinCenter for Analysis Prediction Beijing China Graduate School Academia Sinica Beijing China 《中国地震研究》1995,(3)
The "field" and "source" are two important branches in seismology and earthquake research.In this paper,we use a computer model to study the relation between the field and the source in earthquake activity.In our modeling,a network of nonlinear elements is used to simulate seismic activity of seismic zones in a seismotectonic block.Constant strain rate is enforced on the boundary of the model,cyclic seismic activity,quasi-periodic variation of stress field intensity,and strain energy are observed with high and low fluctuations.There is a main seismicity area in seismic cycles,and the main seismicity area shows the spatial migration during different seismic cycles.If the precursory area is related to high element stress,it is found that the development of precursors in our model is quite complicated.No certain relation between the precursors and earthquakes has been discovered.Anomalies show different characteristics in the seismic quiet period and active period.All of the seismic zones in the system hav 相似文献
4.
The MS7.0 Jiuzhaigou earthquake occurred on August 8, 2017. The earthquake occurred in the vicinity of the Tazang fault, the Minjiang fault and the Huya fault, where the focal mechanism is of the strike slip type. The static and dynamic anomalies of the gravity field can provide important physical field information for studying the structural properties of deep crust. Multi-scale decomposition techniques are used to separate Bouguer gravity at different depths and give some explanation to gravity variations at different time space scales.The results indicate that the wavelet multi-scale results of the EGM2008 model and the measured gravity data are consistent. Through comparative analysis, it is found that the Jiuzhaigou earthquake occurred in the stress enhanced region. The variation of gravity field at different time scales has a certain scientific significance for further understanding potential earthquake risk trend. 相似文献
5.
In the moment-ratio imaging algorithm, which is based on the theory of healing of a wound, the energy of each strong earthquake is distributed around the epicenter according to certain rules, and the features of the Moment-ratio value R are analyzed as the space and time change, so that the relationships between the moment-ration value R and strong earthquakes can be found. In the present paper, regions divided, hypocenter depths and events completed magnitude analyses were carried out in the Chinese catalogue. By applying the moment-ratio imaging algorithm in which the parameters are adjusted, the processes of anomaly evolution which correspond to the epicenter and the surrounding value R before earthquakes of M≥7.0 since 1966 in different areas of China were analyzed. It was found that the range area and imminent time of a coming earthquake could be confirmed quantita- tively by analyzing the abnormal temporal and spatial variation of the value R The results showed that the temporal and spatial variation of the value R could quantitatively reflect the temporal and spatial factors of a coming strong earthquake as well as the rule of medium rupture. 相似文献
6.
Artificial earthquake catalogue simulation is one of the ways to effectively improve the incompleteness of the existing earthquake catalogue,the scarcity of large earthquake records and the improvement of seismological research.Based on the Poisson distribution model of seismic activity and the Gutenberg-Richter magnitude-frequency relationship, the Monte Carlo method which can describe the characteristics of the stochastic nature and the physical experiment process is used.This paper simulates the future seismic catalogues of the Fenhe-Weihe seismic belt of different durations and conducts statistical tests on them. The analysis shows that the simulation catalogue meets the set seismic activity parameters and meets the Poisson distribution hypothesis,which can obtain a better simulated earthquake catalogues that meets the seismic activity characteristics.According to the simulated earthquake catalogues,future earthquake trends in this region are analyzed to provide reference for seismic hazard analysis. 相似文献
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Based on research result concerning the preparation and activity of strong earthquakes in groups and using the finite element method, a finite element dynamic model for Southwest China is established in this paper. Using this model, the stress adjustment in the whole of the Southwest China region in response to the stress change due to strong earthquake occurrence is studied. The preliminary result shows that many strong earthquakes occurred in areas where the stress heightened after the last strong earthquake. So, the finite element model set up in this paper is useful for judging the regions where strong earthquakes are likely to occur in future. 相似文献
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Taking the northeastern Fujian area as an example, we provide some new technological ideas and contents for the historical earthquake investigation of significant engineering construction sites. ① Make sure the integrity of earthquake materials with reference to the regional histories of culture and disasters; ② Evaluate the influence of historical earthquakes on the basis of actual records, review and identify the epicenter location and magnitude of destructive earthquakes. The research by the new technological ideas will endue the investigation of historical earthquakes with new meanings in the cultural phylogeny and credible time domain, so as to make the results of historical earthquake research more scientific. The aim of the paper is to improve the level of historical earthquake investigation for a better service to the engineering construction. 相似文献
9.
Shao Huicheng 《中国地震研究》2007,21(2):189-195
The gestation and occurrence of strong earthquakes are closely related to fault activity, which is not only revealed by abundant experimentation and seismism but also proved by modern seismology. On the Chinese mainland, the relation between earthquake activity and active faults is one of the bases for partitioning potential seismic sources, analyzing the seismotectonics and estimating location of strong earthquakes.Due to the nonuniformity of earth media, instability of observation systems and disturbance of the environment, etc, the variety of observational data is complicated, that is, there is no absolutely "normal" or "abnormal", and seismic anomalies can be divided into many mutually exclusive "abnormal states". In different conditions of combined time-space-strength, determining seismic anomalies by different monomial forecast methods and its efficiency could be different due to the uncertainty of a precursor itself or complexity of the relationship between a precursor and earthquake gestation. It is very difficult to discover and dispose of this difference in actual application in a "two-state" model. But in a "multi-state" model, the difference can be easily reflected and the optimal combination of forecasting parameters for a forecast method can also be determined easily.Based on the "multi-state" precursory model and the optimization method for parameters of earthquake forecast model under the condition of optimal forecast efficiency, the relationship of the spatial location of earthquake with M≥6.0 and active faults in three seismic belts are analyzed. The results demonstrate that in the Hetao Seismic Belt, seismicity is mostly concentrated in the range of 20 km along the fault, the optimization model can forecast the location of potential earthquakes of M≥6.0 near the faults with a relatively high accuracy and the reliability is 0.5; while in the Qilian Mt. Seismic Belt, the reliability only reaches 0.14 when we use the model to estimate earthquakes within 30 km range along the faults. The "multi-state" precursory model, the efficiency-evaluating model and the parameter selection of individual earthquake forecast model based on optimal efficiency are of certain revelatory and practicable meanings for developing knowledge about precursors, investigating the laws of earthquake preparation and searching for optimal forecasting methods. 相似文献
10.
QinChengzhi ZhouChenghu PeiTao LiQuanlin 《中国地震研究》2004,18(2):178-187
The migration of strong earthquakes is an important research topic because the migration phenomena reflect partly the seismic mechanism and involve the prediction of tendency of seismic activity. Research on migration of strong earthquakes has mostly focused on finding the phenomena. Some attempts on getting regularity were comparatively subjective. This paper suggests that there should be indices of migration in earthquake dataset and the indexes should have statistical meaning if there is regularity in the migration of strong earthquakes. In this study, three derivative attributes of migration, i.e., migration orientation, migration distance and migration time interval, were statistically analyzed. Results in the North China region show that the migration of strong earthquakes has statistical meaning. There is a dominant migration orientation (W by S to E by N), a dominant distance ( ≤ 100kin and on the confines of 300 ～ 700km), and a dominant time interval ( ≤ la and on the confines of 3 - 4a). The results also show that the migration will differ slightly with different magnitude range or earthquake activity phase. 相似文献
11.
三维多尺度体曲率的算法及应用(英文) 总被引：2，自引：1，他引：1
为了充分提取与挖掘储层结构及构造信息在时间(深度)和空间上的多尺度特征,构造了一种新的三维多尺度体曲率分析方法,并给出了三维体曲率快速提取算法。与常规的体曲率方法相比,本文方法的改进主要体现在以下两个方面:①在体曲率分析中引入时频域分频展开和对应的空间波数域多尺度自适应微分算子,可同时在时间和空间上反映地震信息的多尺度特征;②将不同尺度的体曲率数据进行有机融合,充分利用了不同尺度曲率异常信息,同时突出有效异常,降低噪声影响,为体曲率属性解释奠定基础。利用该方法处理了陆上和海上三维地震资料,实现了对储层展布、断层及裂缝发育带的检测及多尺度特征的有效刻画。 相似文献
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跨断层形变资料的信息提取与分析是地震研究的重要内容之一。文中以小波分析和信息熵理论为基础,提出了能够反映局部数据信息有序度大小的小波多尺度熵信息提取方法。研究了新疆天山地区跨断层定点形变观测资料强震前小波多尺度熵的变化特征,并应用多元线性回归方法分析了减熵异常与地震三要素之间的关系。结果表明:跨断层形变速率的相对高频成分携带的信息量大于中低频成分,大多数强震前小波多尺度熵有低值异常出现,累计减熵量的对数与震级、异常起始至发震的时间具有显著的线性关系,表现为震级越大,异常起始至发震的时间越长,累计减熵量越大,多个测点整体熵值的减少与大范围的地壳运动及地震活跃期存在一定程度的关联性 相似文献
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基于小波包和峰度赤池信息量准则的P波震相自动识别方法 总被引：2，自引：2，他引：0
基于小波包变换和峰度赤池信息量准则(AIC), 提出了一种新的自动识别P波震相的综合方法, 即小波包-峰度AIC方法． 首先对由加权长短时窗平均比(STA/LTA)法粗略确定的P波到时前后3 s的记录进行小波包三尺度的分解与重构, 分别计算每个尺度重构信号的峰度AIC曲线并将其叠加, 叠加曲线的最小值则为P波震相到时; 然后对原始地震记录进行有限冲激响应自适应滤波以提高信噪比和识别精度; 最后将小波包-峰度AIC方法应用到合成理论地震图及实际地震记录的P波初至自动识别中. 结果表明: 初至清晰度对识别精度的影响比信噪比对其影响更大; 与单独使用加权STA/LTA方法和峰度AIC法相比, 小波包-峰度AIC法具有更强的抗噪能力, 识别精度更高; 当初至清晰时, 小波包-峰度AIC法自动识别与人工识别的P波到时平均绝对差值为(0.077±0.075) s． 相似文献
15.
Shao Huicheng 《中国地震研究》2005,19(1):22-28
INTRODUCTIONWiththedevelopmentofsocietyandquickurbanizationfeaturedbyacentralizationofpopulationsandeconomies ,itisverylikelythatastrongearthquakewillcausethedeathofhundredsandthousandsofpeopleandhugelossofproperty .Forexample ,intheepicenterareaoftheBame… 相似文献
16.
联合小波变换与偏振分析自动拾取微地震P波到时 总被引：1，自引：0，他引：1
对微地震P波到时的自动拾取是微地震信号分析和数据处理的主要目标之一。基于小波变换的多尺度分析思想,对微地震信号进行小波处理后的小波系数代替原始信号,应用包含在小波变换系数中的信号偏振信息,提出了联合小波变换与偏振分析自动拾取微地震信号P波到时的方法。通过对嘉阳煤矿监测的实际微地震数据进行小波变换,用多尺度小波分解的各个尺度单支重构信号构成协方差矩阵,求解不同尺度协方差矩阵的最大特征值和次大特征值求取P波到时定位函数,实现P波到时的自动拾取,取得了满意的结果. 相似文献
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The research on relationship between wavelet transform on vertical deformation and moderate earthquakes in hexi region, Gansu Province 总被引：1，自引：0，他引：1
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利用sym5小波包基函数对小震级天然地震和人工爆破波形进行4层小波包分解并绘制了时频谱图.通过时频谱图可直观得出, 爆破频率成分简单, 时频谱聚集性较好. 为寻求定量的识别指标, 综合P波和S波小波包变换结果, 提出并定义了P/S能量比. 分析识别效果较好的 P/S能量比判据得出爆破的P波主频集中在频段3.125—9.375 Hz处, 地震频率成分较复杂, S波在高频12.5—23.4375 Hz处也较发育, 在这些频段上, 爆破的P波与S波差异要大于地震的P波与S波差异. 作为小波包判据研究的补充, 文中也提取分析了P波的能量比与S波的能量比. 能量比判据识别结果表明, 人工爆破与天然地震的频率成分存在差异, 通过小波包变换能够提取有效的识别判据. 相似文献
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用于监测四川地区重力场随时间变化的流动重力测网于2008年5月12日汶川MS8.0地震后进行了全面改造, 形成了新的闭合环线并对整网点位每年实施2次重力观测工作. 该文以2010—2012年获取的5期流动重力资料为基础, 分别采用小波多尺度分解和三维视密度反演等位场分离方法, 对测区内重力场的动态变化进行多层次分解及异常特征提取, 以探求四川测区范围内重力异常动态变化特征以及地震前后不同深度范围内密度变化情况与重力场响应之间的关系. 结果表明, 对同一期资料进行小波分解得到不同阶次的细节图像, 揭示了不同深度处重力异常动态变化特征; 分解结果同时也表明了四川测区范围内重力场的变化形态与川内特有的断裂构造格架和深部结构环境及过渡带特征密切相关. 通过对不同时期的差分重力异常资料进行三维视密度反演对比研究发现, 在地震前后四川测区范围内由浅到深密度变化呈现出不同程度的差异, 震区附近出现较为明显的横向密度变化特征且浅层物质密度局部性的异常变化差异较为突出, 测区范围内中上地壳深度层密度反演切片显示出的趋势性差异基本上反映了地震前后测区内地下物质的动态变化趋势, 因此, 深刻认识不同深度范围内重力场的动态演化特征, 对研究壳内物质密度变化以及与地震的孕育和发展有关的深部介质环境具有积极的意义. 相似文献