共查询到20条相似文献,搜索用时 187 毫秒
1.
地震复发间隔的概率分布是计算地震发生概率的基础.利用我国历史地震目录资料,统计分析中国大陆中强地震归一化区域复发间隔,分析发现中国大陆中强地震活动兼具周期性和丛集性特点.采用对数正态分布与指数分布构建混合概率分布模型,通过最小二乘法拟合混合概率分布函数的最优参数.拟合结果的误差分析表明,混合概率分布模型更加符合中国大陆... 相似文献
2.
通过计算前人研究所给出的中国大陆26条活动地块边界带上地震过程的变异系数, 分析了各边界带的地震活动类型, 结果表明中国大陆东部地区的边界带地震都表现为丛集过程, 西部地区大多是泊松过程或者准周期过程, 尤其是大陆板块俯冲作用强烈的边界带上地震活动主要呈现为泊松过程, 青臧高原北部和东部地区的边界带都表现为准周期过程, 并讨论了可能的物理机制。 并在以往研究的基础上, 基于对数正态分布函数, 计算了各边界带目前地震发生的累计概率以及未来五年内地震发生的条件概率, 探讨了各活动地块边界带的危险程度等。 相似文献
3.
本文利用基于广义帕累托分布的超阈值分布模型,对中国大陆活动地块边界带强震震级分布特征开展研究,给出了各活动地块边界带强震震级的广义帕累托分布参数估计。结果表明,广义帕累托分布较好地拟合了各边界带强震数据,形状参数估计均为负值,说明对应震级应有上限,因此广义帕累托分布为潜在震级上限提供了一种自然的刻画。在此基础上,估计了震级上限,并给出了分布0.99997高分位数估计,通过与历史最大震级比较发现,高分位数估计相对稳健。在地震发生过程为泊松过程假设下,推导了广义帕累托分布与广义极值分布之间的联系,揭示了一种利用强震数据推断最大震级分布的可能途径。 相似文献
4.
5.
人工地震目录模拟是改进现有地震目录不完备性、弥补大地震记录稀缺,以及完善地震学相关研究的有效途径之一。本文基于地震活动的泊松分布模型、古登堡-里克特震级-频度关系,利用能较逼真描述具有随机性质事物特点及物理实验过程的蒙特卡洛方法,模拟汾渭地震带未来30、50、100年等不同时长的地震目录,并对其进行统计检验。分析表明,模拟地震目录符合设定的地震活动性参数和泊松分布假设特征。依据模拟地震目录,对未来该区域地震趋势进行了分析,以期为地震危险性分析提供参考。 相似文献
6.
利用中国西部古地震和历史地震资料建立了特征地震模型并与分档泊松模型结合组成混合地震模型。研究了青藏高原东南缘的重要地震带鲜水河-小江断裂地区的地震危险性,并与1990年出版的中国地震区划图结果进行了比较,表明在1786年曾经发生过73/4级地震的康定地区(离浙时间为213a,地震复地周期为320a)的地震概率大于后,Ⅷ度区面积同样是前大于后。这说明地震离逝时间与地震复发周期关系对地震危险性计算是有影响的,特征地震与混合地震模型的引入解决了泊松模型无记忆性的缺陷,使计算的结果更科学、合理。 相似文献
7.
8.
华南地区中强地震重复特征初步分析 总被引:2,自引:2,他引:0
运用时间相依的布朗过程时间模型和泊松模型,分别计算了炉霍潜源和道孚潜源7.0≤M<7.5和7.5≤M<8.0震级档未来50a的发震概率,并将其与根据中国地震动参数区划图(2001)潜在震源区划分综合方案且运用分档泊松模型所得的计算结果进行对比分析。结果表明:①应用地震矩率方法得到的各断裂段特征化地震复发间隔,无论是BPT模型或泊松模型所得到的炉霍和道孚潜源在7.0≤M<7.5震级档的发震概率计算结果,均远大于根据中国地震动参数区划图(2001)潜在震源区划分综合方案所得的计算结果;②对于使用同样的由地震矩率方法得到的各断裂段特征化地震复发间隔数据,BPT模型和泊松模型所得的计算结果也不相同。 相似文献
9.
10.
11.
The paper studies the statistical properties of deep earthquakes around North Island, New Zealand. We first evaluate the catalogue
coverage and completeness of deep events according to cusum (cumulative sum) statistics and earlier literature. The epicentral,
depth, and magnitude distributions of deep earthquakes are then discussed. It is worth noting that strong grouping effects
are observed in the epicentral distribution of these deep earthquakes. Also, although the spatial distribution of deep earthquakes
does not change, their occurrence frequencies vary from time to time, active in one period, relatively quiescent in another.
The depth distribution of deep earthquakes also hardly changes except for events with focal depth less than 100 km. On the
basis of spatial concentration we partition deep earthquakes into several groups—the Taupo-Bay of Plenty group, the Taranaki
group, and the Cook Strait group. Second-order moment analysis via the two-point correlation function reveals only very small-scale
clustering of deep earthquakes, presumably limited to some hot spots only. We also suggest that some models usually used for
shallow earthquakes fit deep earthquakes unsatisfactorily. Instead, we propose a switching Poisson model for the occurrence
patterns of deep earthquakes. The goodness-of-fit test suggests that the time-varying activity is well characterized by a
switching Poisson model. Furthermore, detailed analysis carried out on each deep group by use of switching Poisson models
reveals similar time-varying behavior in occurrence frequencies in each group. 相似文献
12.
Mixed model for interoccurrence times of earthquakes based on the expectation-maximization algorithm 总被引:1,自引:0,他引:1
In this paper, the goodness-of-fit test based on a convex combination of Akaike and Bayesian information criteria is used
to explain the features of interoccurrence times of earthquakes. By analyzing the seismic catalog of Iran for different tectonic
settings, we have found that the probability distributions of time intervals between successive earthquakes can be described
by the generalized normal distribution. This indicates that the sequence of successive earthquakes is not a Poisson process.
It is found that by decreasing the threshold magnitude, the interoccurrence time distribution changes from the generalized
normal distribution to the gamma distribution in some seismotectonic regions. As a new insight, the probability distribution
of time intervals between earthquakes is described as a mixture distribution via the expectation-maximization algorithm. 相似文献
13.
In this first paper of two, a numerical simulation model capable of simulating the spatial variability of rainfall partitioning within a canopy is presented. The second paper details how the model is parameterized, and some testing of its capabilities. The first stage of the model is to derive the mature canopy structure. This is achieved through simplified individual tree structures and a random placement routine based on a modified Poisson distribution. Following this the spatial discretization for throughfall is attained as a series of layers of triangles with a tree trunk at every apex. The number of layers is derived from the leaf area index through a modified Poisson distribution. Seasonal variation in the deciduous canopy is simulated through a time vector routine. The rainfall partitioning section of the model is based upon the Rutter model which has been modified to each individual triangle layer. The main feature of this model is that it offers a method of simulating rainfall partitioning at a scale that is a function of the size of the elementary physical components (tree and leaf scale). This can be used to investigate soil moisture variations under a canopy, or to study the variations within the forest hydrological processes themselves. © 1997 John Wiley & Sons, Ltd. 相似文献
14.
C. Onof R. E. Chandler A. Kakou P. Northrop H. S. Wheater V. Isham 《Stochastic Environmental Research and Risk Assessment (SERRA)》2000,14(6):384-411
Over a decade ago, point rainfall models based upon Poisson cluster processes were developed by Rodriguez-Iturbe, Cox and
Isham. Two types of point process models were envisaged: the Bartlett–Lewis and the Neyman–Scott rectangular pulse models.
Recent developments are reviewed here, including a number of empirical studies. The parameter estimation problem is addressed
for both types of Poisson-cluster based models. The multiplicity of parameters which can be obtained for a given data set
using the method of moments is illustrated and two approaches to finding a best set of parameters are presented. The use of
a proper fitting method will allow for the problems encountered in regionalisation to be adequately dealt with. Applications
of the point process model to flood design are discussed and finally, results for a model with dependent cell depth and duration
are given. Taking into account the spatial features of rainfall, three multi-site models are presented and compared. They
are all governed by a master Poisson process of storm origins and have a number of cell origins associated with each storm
origin. The three models differ as to the type of dependence structure between the cell characteristics at different sites.
Analytical properties are presented for these models and their ability to represent the spatial structure of a set of raingauge
data in the South-West of England is examined. Continuous spatial-temporal models are currently being developed and results
are presented for a model in which storm centres arrive in a homogeneous Poisson process in space-time, and cells follow them
in time according to a Bartlett–Lewis type cluster. Examples of simulations using this model are shown and compared with radar
data from the South-West of England. The paper concludes with a summary of the main areas in which further research is required. 相似文献
15.
Introduction Stress release model (SRM) was proposed by Vere-Jones (1978) for statistical study of seismicity. Physically it is a stochastic version of the elastic rebound theory of earthquake genesis. The classical elastic rebound model suggests that the stress has been slowly accumulating until the burst of an earthquake occurrence for stress release. This can be simulated by the jump Markov process in stochastic field, and SRM was developed on the basis of Knopoff (s Markov model (Knop… 相似文献
16.
Shallow earthquakes usually show obvious spatio-temporal clustering patterns. In this study, several spatio-temporal point process models are applied to investigate the clustering characteristics of the well-known Tangshan sequence based on classical empirical laws and a few assumptions. The relative fit of competing models is compared by Akaike Information Criterion. The spatial clustering pattern is well characterized by the model which gives the best fit to the data. A simulated aftershock sequence is generated by thinning algorithm and compared with the real seismicity. 相似文献
17.
SynthesizedPoissonandrenewalmodelanditsapplicationinseismichazardanalysisHan-YaoCHEN(陈汉尧)andYu-XianHU(胡聿贤)(InstituteofGeophys... 相似文献
18.
Zdenka Schenková 《Pure and Applied Geophysics》1973,109(1):1700-1711
Summary The time distribution of earthquake occurrence in the European area is investigated by statistical laws. The original data of shallow-focus earthquakes are taken from the European catalogue 1901–1967. Evidence is given that the process with the negative binomial entries as a model describing the occurrence of shallow-focus earthquakes is better than the Poisson process. Further, the influence of magnitude classes and magnitude threshold value on the time distribution of earthquake occurrence is examined.Communication presented at the XIII General Assembly of the European Seismological Commission in Brasov in 1972. 相似文献
19.
3 Conclusions The research of some theoretical Contor models of multi-scale and the numerical model of seismic spatial distribution show
that the physical property of anomalies in seismic fractal spectrums is due to an increment of nonuniformity in the point
set (earthquakes), in another word, the complexity increases. It is exactly the general precursory that the distribution pattern
becomes complex from simple or nonuiform from uniform. So seismic multi-fractal spectrums is one of the best methods or tools
for describing the complexity of seismic temporal-spatial distribution patterns. According to this view of point, taking the
anomalies of the seismic multi-fractal spectrum as the earthquake prediction criterion is very valuable and worth while further
studying.
This project is supported by Chinese Joint Seismological Science Foundation. 相似文献
20.
In this paper, by means of the statistical analysis method of stochastic spatial point process, statistical analysis of spatial
distribution of earthquakes in the large northern region of China is made. Emphasis is on the test and analysis of the complete
spatial randomness, correlation of earthquake distribution in the different magnitude interval and random labeling. It is
shown by the analysis that the spatial distribution of earthquakes in the large northern region is “clustered”, the distributions
of earthquakes in different magnitude interval are positively correlated and can be modeled by a two-dimensional process.
The results obtained in the paper can be used for the establishment of a reasonable spatial distribution model and have some
application in the reasonable estimation of seismic hazard.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 129–135, 1993. 相似文献