Likelihood analysis of earthquake catalogues   总被引：5，自引：0，他引：5  

Y. Y. Kagan 《Geophysical Journal International》1991,106(1):135-148

We apply several classes of stochastic multidimensional models to statistical analysis of earthquake catalogues using likelihood methods. We investigate the importance of including different earthquake parameters in the model: epicentral coordinates, hypocentral depth, time limits for interearthquake interaction, and especially spatial distribution of earthquakes as well as spatial aftershock patterns. Results of this study combined with other investigations, suggest that most distributions controlling earthquake interaction have a fractal or scale-invariant form. Developed models are used for statistical analysis of several earthquake catalogues to evaluate parameters of earthquake occurrence. These parameters are shown to be similar for shallow earthquakes of different magnitude ranges and seismogenic regions, confirming self-similarity of the earthquake process. Whereas intermediate earthquakes seem to emulate the pattern of shallow earthquake occurrence, albeit at a much smaller aftershock rate, deep earthquakes differ significantly in their properties. Predictability of standard shallow earthquake catalogues has been analysed; we present evidence that for the best available catalogues the predictability is close to 10 bits per earthquake. Several synthetic earthquake catalogues have been created and processed through the likelihood inversion scheme. The results from likelihood analysis of these catalogues confirm our approach.  相似文献   

Undead earthquakes   总被引：1，自引：0，他引：1  

R.?M.?W.?MussonEmail author 《Journal of Seismology》2005,9(1):111-114

This short communication deals with the problem of fake earthquakes that keep returning into circulation. The particular events discussed are some very early earthquakes supposed to have occurred in the U.K., which all originate from a single enigmatic 18th century source.  相似文献   

GHASP: an Hα kinematic survey of spiral and irregular galaxies – IV. 44 new velocity fields. Extension, shape and asymmetry of Hα rotation curves     

O. Garrido  M. Marcelin  P. Amram  C. Balkowski  J. L. Gach  J. Boulesteix 《Monthly notices of the Royal Astronomical Society》2005,362(1):127-166

We present Fabry–Perot observations obtained in the frame of the GHASP survey (Gassendi HAlpha survey of SPirals). We have derived the Hα map, the velocity field and the rotation curve for a new set of 44 galaxies. The data presented in this paper are combined with the data published in the three previous papers providing a total number of 85 of the 96 galaxies observed up to now. This sample of kinematical data has been divided into two groups: isolated (ISO) and softly interacting (SOFT) galaxies. In this paper, the extension of the Hα discs, the shape of the rotation curves, the kinematical asymmetry and the Tully–Fisher relation have been investigated for both ISO and SOFT galaxies. The Hα extension is roughly proportional to R₂₅ for ISO as well as for SOFT galaxies. The smallest extensions of the ionized disc are found for ISO galaxies. The inner slope of the rotation curves is found to be correlated with the central concentration of light more clearly than with the type or the kinematical asymmetry, for ISO as well as for SOFT galaxies. The outer slope of the rotation curves increases with the type and with the kinematical asymmetry for ISO galaxies but shows no special trend for SOFT galaxies. No decreasing rotation curve is found for SOFT galaxies. The asymmetry of the rotation curves is correlated with the morphological type, the luminosity, the  ( B − V )  colour and the maximal rotational velocity of galaxies. Our results show that the brightest, the most massive and the reddest galaxies, which are fast rotators, are the least asymmetric, meaning that they are the most efficient with which to average the mass distribution on the whole disc. Asymmetry in the rotation curves seems to be linked with local star formation, betraying disturbances of the gravitational potential. The Tully–Fisher relation has a smaller slope for ISO than for SOFT galaxies.  相似文献   

实验室X射线天体物理     

梁贵云  赵刚 《天文学进展》2005,23(3):248-271

正在进行的实验室天体物理测量解决了X射线天文学的一些问题，这些实验产生了大量可靠的原子数据，它们既可用于电荷分布中电离与复合截面的计算，又可用于对X射线谱线形成的线表、激发截面及双电子复合系数的理解。另有一部分实验注重于解决天体观测的难题，以及验证现有的和寻找新的X射线谱线诊断。讨论了上述实验产生的数据类型，并展示了实验室测量如何为卫星（ASCA、EUVE、Chandra、XMM和ASTRO-E2）观测提供实验依据．  相似文献   

Corrections to the luni-solar precession derived from a compilation catalogue of extragalactic radio sources     

H. G. Walter 《Celestial Mechanics and Dynamical Astronomy》1992,53(1):71-80

Observation catalogues of extragalactic radio sources obtained by Very long Baseline Interferometry during the last decade agree in the mean to a few milliarcseconds (mas). Within this range the position differences show constant, linear and periodic offsets. To reduce the influence of individual catalogue properties the construction of a compilation catalogue seems to be the appropriate procedure. In some detail the compilation method is described providing simultaneous adjustment of source positions and catalogue corrections. The compilation catalogue consists of 40 objects having positional errors of 0.2 mas in right ascension (RA) and 0.3 mas in declination (Dec). Comparing this catalogue with the IERS Celestial Reference Frame compiled by means of other precepts yields weighted root-mean-square differences of 0.7 mas in RA and 1.3 mas in Dec. Finally, the terms of general precession in RA and Dec are included in the adjustment process giving estimates of the correction to the luni-solar precession between –1 and –3 mas/yr, the latter figure applying when some early data are added.  相似文献   

Estimation of earthquake magnitudes from epicentral intensities and other focal parameters in Central and Southern Europe   总被引：3，自引：0，他引：3  

Rolf Gutdeutsch  Diethelm Kaiser  Gerhard Jentzsch 《Geophysical Journal International》2002,151(3):824-834

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Spectral characteristics of the seismic hazard between the alps and the dinarides     

L. Peruzza  L. Sirovich  D. Slejko 《Soil Dynamics and Earthquake Engineering》1994,13(3)

Empirical correlations between response spectra, magnitude, distance from the source and geological site conditions are introduced in a regional study of seismic hazard. A 350-year earthquake catalogue is treated by means of the statistics of extremes and both the spectral amplitudes (pseudovelocity) corresponding to a series of frequency bands are separately mapped, and the complete predicted response spectra calculated at some sites. Three kinds of geological site conditions are considered: thick and thin (less than 20 m deep) alluvium, and rock. A particular dependence of the results on the geographical distribution of earthquakes and on their magnitudes is commented. The seismic hazard of the study area is also computed by applying a traditional regression between peak ground velocity, magnitude and distance; a comparison with the seismic hazard given by the frequency dependent psuedovelocity indicates the extent of the uncertainty associated with the common practice of scaling response spectra directly from ground motion parameters.  相似文献   

台站地震分析报送软件设计     

王锋  胡光武  李伟  沙宏武  殷翔  皇甫德银 《高原地震》2012,24(3):45-47

详细介绍台站地震分析报送软件的设计思路与实现方法及各模块的功能特点。该软件利用VB开发,能自动识别并转换台站常用分析软件的产出结果,通过ODBC5．1驱动,完成远程入库;使用书签技术实现了工作日志的编辑、浏览及打印,满足地震台站工作的需要。  相似文献   

Reconstruction of cosmological initial conditions from galaxy redshift catalogues     

Pierluigi Monaco  George Efstathiou 《Monthly notices of the Royal Astronomical Society》1999,308(3):763-779

We present and test a new method for the reconstruction of cosmological initial conditions from a full-sky galaxy catalogue. This method, called ZTRACE, is based on a self-consistent solution of the growing mode of gravitational instabilities according to the Zel'dovich approximation and higher order in Lagrangian perturbation theory. Given the evolved redshift-space density field, smoothed on some scale, ZTRACE finds, via an iterative procedure, an approximation to the initial density field for any given set of cosmological parameters; real-space densities and peculiar velocities are also reconstructed. The method is tested by applying it to N -body simulations of an Einstein–de Sitter and an open cold dark matter universe. It is shown that errors in the estimate of the density contrast dominate the noise of the reconstruction. As a consequence, the reconstruction of real-space density and peculiar velocity fields using non-linear algorithms is little improved over those based on linear theory. The use of a mass-preserving adaptive smoothing, equivalent to a smoothing in Lagrangian space, allows an unbiased (although noisy) reconstruction of initial conditions, as long as the (linearly extrapolated) density contrast does not exceed unity. The probability distribution function of the initial conditions is recovered to high precision, even for Gaussian smoothing scales of ∼5  h ⁻¹ Mpc, except for the tail at δ ≥1. This result is insensitive to the assumptions of the background cosmology.  相似文献   

Identifications of FIRST radio sources in the NOAO Deep Wide‐Field Survey     

K. El Bouchefry  C.M. Cress 《Astronomische Nachrichten》2007,328(6):577-585

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