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The Athens earthquake (7 September 1999): intensity distribution and controlling factors 总被引：1，自引：0，他引：1
The Athens earthquake, Ms=5.9, that occurred on 7th September 1999 with epicenter located at the southern flank of Mount Parnitha (Greece, Attiki) according to instrumental data, is attributed to the reactivation of an ESE–WNW south- dipping fault without surficial expression. The earthquake caused a large number of casualties and extensive damage within an extended area. Damage displayed significant differentiation from place to place, as well as a peculiar geographic distribution. Based on geological, tectonic and morphological characteristics of the affected area and on the elaboration of damage recordings for intensity evaluation, it can be safely suggested that intensity distribution was the result of the combination of a number of parameters both on macro and microscale. On the macroscale, the parameters are the strike of the seismogenic fault, seismic wave directivity effects and to an old NNE–SSW tectonic structure, and they are also responsible for the maximum intensity arrangement in two perpendicular directions ESE–WNW and NNE–SSW. On the microscale, site foundation formations, old tectonic structures buried under recent formations and morphology are the parameters that differentiated intensities within the affected area. 相似文献
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<Emphasis Type="Italic">M</Emphasis><Subscript>W</Subscript>9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis 
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下载免费PDF全文 Panayiotis A. Varotsos Nicholas V. Sarlis Efthimios S. Skordas Mary S. Lazaridou-Varotsos 《地震科学（英文版）》2017,30(4):183-191
This paper reviews the precursory phenomena of the 2011 M W9 Tohoku earthquake in Japan that emerge solely when we analyze the seismicity data in a new time domain termed natural time. If we do not consider this analysis, important precursory changes cannot be identified and hence are missed. Natural time analysis has the privilege that enables the introduction of an order parameter of seismicity. In this frame, we find that the fluctuations of this parameter exhibit an unprecedented characteristic change, i.e., an evident minimum, approximately two months before Tohoku earthquake, which strikingly is almost simultaneous with unique anomalous geomagnetic field variations recorded mainly on the z component. This is consistent with our finding that such a characteristic change in seismicity appears when a seismic electric signal (SES) activity of the VAN method (from the initials of Varotsos, Alexopoulos, Nomicos) initiates, and provides a direct confirmation of the physical interconnection between SES and seismicity. 相似文献
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Nicholas V.Sarlis Panayiotis A.Varotsos Efthimios S.Skordas Seiya Uyeda Jacques Zlotnicki Toshiyasu Nagao Anatoly Rybin Mary S.Lazaridou-Varotsos Konstantina A.Papadopoulou 《地震科学（英文版）》2018,31(1):44-51
The Varotsos-Alexopoulos-Nomicos(VAN) method of short-term earthquake prediction was introduced in the 1980s. The VAN method enables estimation of the epicenter, magnitude and occurrence time of an impending earthquake by observing transient changes of the electric field of the Earth termed seismic electric signals(SES). Here, we present a few examples of SES observed in various earthquake prone areas worldwide. 相似文献
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The problems of fragmentation, angular momentum, and magnetic flux during star formation are reviewed briefly. Then the resolution of the angular momentum problem through magnetic braking is studied rigorously.A disk-like interstellar cloud of uniform density
cl
is given an initial angular velocity
o
about its axis of symmetry, which isaligned with an initially uniform, frozen-in magnetic field. Torsional Alfvén waves transport angular momentum from the cloud to the external medium, which has a uniform density
ext
. The angular velocity of the cloud (
cl
) is determined analytically as a function of space and time for different ratios
cl
/
ext
(the only free parameter in the equations), representing different stages of contraction. Despite dissimilar transient response of the cloud (or fragment) structure to different initial conditions, the characteristic time for magnetic braking of the rotation of the cloud (or fragment) as a whole is remarkably insensitive to the initial conditions and independent of the stage of contraction. The latter conclusion is in agreement with an approximate result obtained recently (Mouschovias, 1978; 1979a).A cylindrical cloud (or fragment) of uniform density is also imparted an initial angular velocity about its axis of symmetry with respect to the external medium. The frozen-in magnetic field is now initially radial andperpendicular to the axis of symmetry. In this case magnetic braking becomes more efficient upon contraction. It is more efficient than the aligned rotator case typically by one order of magnitude. The angular momentum problem can be resolved in about 106 yr during the early stages of cloud contraction. Planetary systems, such as the Sun-Jupiter pair, become dynamically possible. A stage exists in which a cloud (or fragment) is in retrograde rotation with respect to its surroundings. This provides the first and only observable prediction of magnetic braking in action. It also constitutes a natural explantation of retrograde rotation in stellar and planetary systems.This work was supported in part by the National Science Foundation under grant NSF AST-77-23568.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy. 相似文献
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Spatial-temporal rainfall modelling for flood risk estimation 总被引：4，自引：6，他引：4
H. S. Wheater R. E. Chandler C. J. Onof V. S. Isham E. Bellone C. Yang D. Lekkas G. Lourmas M.-L. Segond 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(6):403-416
Some recent developments in the stochastic modelling of single site and spatial rainfall are summarised. Alternative single
site models based on Poisson cluster processes are introduced, fitting methods are discussed, and performance is compared
for representative UK hourly data. The representation of sub-hourly rainfall is discussed, and results from a temporal disaggregation
scheme are presented. Extension of the Poisson process methods to spatial-temporal rainfall, using radar data, is reported.
Current methods assume spatial and temporal stationarity; work in progress seeks to relax these restrictions. Unlike radar
data, long sequences of daily raingauge data are commonly available, and the use of generalized linear models (GLMs) (which
can represent both temporal and spatial non-stationarity) to represent the spatial structure of daily rainfall based on raingauge
data is illustrated for a network in the North of England. For flood simulation, disaggregation of daily rainfall is required.
A relatively simple methodology is described, in which a single site Poisson process model provides hourly sequences, conditioned
on the observed or GLM-simulated daily data. As a first step, complete spatial dependence is assumed. Results from the River
Lee catchment, near London, are promising. A relatively comprehensive set of methodologies is thus provided for hydrological
application. 相似文献
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E. L. Lekkas 《Natural Hazards》2002,25(3):305-306
Volume Contents
Contents of Volume 25 相似文献8.
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Since its introduction in 2001, natural time analysis has been applied to diverse fields with remarkable results. Its validity has not been doubted by any publication to date. Here, we indicate that frequently asked questions on the motivation and the foundation of natural time analysis are directly answered if one takes into account the following two key points that we have considered as widely accepted when natural time analysis was proposed: first, the aspects on the energy of a system forwarded by Max Planck in his Treatise on Thermodynamics; second, the theorem on the characteristic functions of probability distributions which Gauss called Ein Schönes Theorem der Wahrscheinlichkeitsrechnung (beautiful theorem of probability calculus). The case of the time series of earthquakes and of the precursory Seismic Electric Signals are discussed as typical examples. 相似文献
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Old?ich Novotny Efthimios Sokos Vladimír Plicka 《Studia Geophysica et Geodaetica》2012,56(4):1007-1018
The western part of the Corinth Gulf attracts attention due to its seismically active fault system and considerable seismic hazard. A moderate size earthquake occurred close to the town of Efpalio on January 18, 2010, followed by a sequence of smaller earthquakes. In the present paper we use this sequence to derive a local structural model for the region in the vicinity of Efpalio. The model is based on the minimization of traveltime residuals. In particular, we used arrival times from 51 selected events recorded on January 19 and 20 by at least 5 stations at epicentral distances less than about 25 km. A variant of the method of conjugate gradients has been used for this purpose. In comparison with several previous models, the new model is characterized by higher velocities to a depth of about 8 km. The velocity ratio in the model is vP / vS = 1.83. The hypocentres of the selected earthquakes lay at depths between about 5 and 9 km, but their distribution is rather irregular. 相似文献