共查询到20条相似文献，搜索用时 31 毫秒
1.
On July 28, 1976, a major earthquake (M=7.9) occurred in the Tangshan region of China. After the earthquake, it was found that astronomical time-latitude anomalies were observed preceeding the occurrence of the earthquake. These observations had been obtained on the Astrolabe of the Beijing Astronomical Observatory and the VZT of Tianjin Latitide Station, which are just located around the epicentre. The anomalies were in the analyses of the time and latitude residuals, and there are more examples verifying these phenomena. However, all those examples were found in post-earthquake analyses. In this paper we discuss the possibility of earthquake prediction and forecast from the rediduals of astronomical time-latitude. For example, series of the five-day means are analyzed. The observations were supposed to be terminated two weeks before the earthquake, and the data are then analyzed a year backward. After removing their averages, the standard deviations are calculated of these series are calculation. Eight earthquakes were chosen as the events to be examined, (see Table). Most of the related instruments obtained excellent observations. The results are shown in the Figure. It is evident that abnormal peaks of RT and RF appeared before each earthquake. Thus we may conclude the followings:
- Under the normal observation conditions, one high predision instruments could inform about a major earthquake a few weeks or a few days before it occurrs.
- The astronomical observations are seriously affected by the weather and observers and so they are some what uncertain.
2.
Possible Ionospheric Electromagnetic Perturbations Induced by the Ms7.1 Yushu Earthquake 总被引：1，自引：0，他引：1
Zeren Zhima Shen Xuhui Zhang Xuemin Cao Jinbin Huang Jianping Ouyang Xinyan Liu Jing Bingqing Lu 《Earth, Moon, and Planets》2012,108(3-4):231-241
The power spectrum density (PSD) of magnetic field in the ELF/VLF band recorded by the experiment IMSC onboard the DEMETER satellite were used to study the Ms7.1 Yushu earthquake taking place on April 13, 2010 in China. The results indicate that possible ionospheric electromagnetic perturbations occurring 4?days before the earthquake in the frequency range [370–897?Hz]. Along the orbit 30880_up, which passed over the epicenter area on 9 April, enhanced PSD value of magnetic field at 410?Hz was detected both over the epicentral area and its conjugate point in the southern hemisphere. While on revisited orbits during other days (before and after the earthquake) the magnetic field spectra remained at a relatively low level. In order to be sure that the electromagnetic disturbances were induced by this Yushu earthquake, relative variations of the magnetic field in the ELF/VLF range [370–897?Hz] were calculated and compared with the normal background during 3?years (2007, 2008 and 2009) in the time interval from Jan. 1st to Apr. 30 and in the area [23°N–43°N, 86°E–106°E]. The results show that the normal level of magnetic field in this area is relatively low (~10?7?nT2/Hz), but a large increase occurred from Apr. 1st to Apr. 14 which exceeds 5σb. After the earthquake, the magnetic field in the ELF/VLF range gradually decreased. In order to exclude the influence of geomagnetic field activity, we selected only the data recorded during magnetically quiet local night-times. In addition, artificial noises were also removed from the dataset used in the present paper. Therefore the observed perturbations were independent of geomagnetic field disturbances, and might be attributed to seismic activity. 相似文献
3.
Earthquakes are one of the most destructive and harmful natural disasters, especially in recent years, the 2008/5/12 Wenchuan M7.9 earthquake, the 2011/3/11 Tohoku M9.0 earthquake and the 2012/4/11 Sumatra M8.6 earthquake have caused a significant impact to the human life. In this paper, we make a study of the temporal and spatial distribution of the Global Positioning System Total Electron Content (GPS TEC) anomalies prior to the three strong earthquakes by the method of statistical analysis. Our results show that the pre-earthquake ionospheric anomalies are mainly positive anomalies and take the shape of a double-crest structure with a trough near the epicenter. The ionospheric anomalies do not coincide with the vertical projection of the epicenter of the subsequent earthquake, but mainly localize in the near-epicenter region and corresponding ionospheric anomalies are also simultaneously observed in the magnetic conjugate region prior to the three earthquakes. In addition, the amplitude and scale-size of the ionospheric ΔTEC are different with the magnitude of the earthquake, and the horizontal scale-size of the greatest anomalies before the Tohoku M9.0 earthquake is ～30° in longitude and ～10° in latitude, with the maximum amplitude of TEC disturbances reaching ～20 TECu relative to the background. The peak of anomaly enhancement usually occurs in the afternoon to sunset (i.e. between 14:00 and 18:00 local time) which lasts for approximate 2 hours. Possible causes of these anomalies are discussed, and after eliminating the effect of solar activities and magnetic storms it can be concluded that the detected obvious and regular anomalous behavior in TEC within just a few days before the earthquakes is related with the forthcoming earthquakes with high probability. 相似文献
4.
用太阳系主要天体的位置建立特大地震的时间预测模型 总被引：5，自引：0，他引：5
根据某类事件发生时太阳系主要运动天体的位置，通过对其历史资料的归算，尝试并设计出一种具有普适性的事件时间预测模型．以1900-1980年间全球所有8级及以上的99次地震为例，定义与天体特征位置(视黄经)相关的发震率，初步建立预测发震时刻的概率曲线．指出这可能成为研究地震预报问题的新途径． 相似文献
5.
Gu Zhen-Nian 《Earth, Moon, and Planets》1996,74(1):35-47
The earthquake produces a global static displacement field due to the dislocation in the epicenter. This displacement field in turn changes the Earth's inertia tensor, hence exciting the variation of both polar motion and length of day. In general, large earthquake produces greater displacement field, which has greater effects upon the earth rotational properties. In spite of scientists efforts in the last decades, it is found that the polar motion and the length of day excited by earthquake are at least two orders of magnitude less than those derived from observation. In the future with high observational accuracy the effect of earthquake on polar motion and length of day would be observable.Using the fault plane parameters, the location of epicenter and the expression given by Dahlen as well as the step function, the accumulative change of the axial and equatorial moments of inertia of the Earth earthquake occurring in period of 1977–1994 is estimated in this paper. Results have shown that change of pole axis direction induced by single earthquake is independent of the magnitude of the earthquake, which is random, but large earthquake contributes most to the accumulative change of direction of polar drift. The earthquake tends to make the drift of rotational pole towards the direction of 130–150 E. This direction is roughly different to that inferred from observations. Accumulative changes of both the two equatorial principal moments and the axial moment of inertia of the Earth present the strongest non-randomness and secular behaviour. The change depends upon the slip angle of the fault movement in a large extent. 相似文献
6.
On 11 April 2012, a strong earthquake of magnitude Ms8.6 occurred near the west coast of Northern Sumatra, Indonesia. In this paper, we investigated the morphological characteristics of anomalous variations in Global Positioning System Total Electron Content (GPS TEC) prior to the earthquake by the method of the statistical analysis. It was found the TEC anomaly was firstly decreased, then, it became more enhanced, finally, it decreased, the peak of anomaly enhancement arose from 13:00–17:00 LT on April 5 lasted for ～4 hours and the anomalous ionospheric regions extended to ～40° in longitude and ～20° in latitude, its location did not coincide with the vertical projection of the epicenter, but lies at the north and south of the geomagnetic equator, meanwhile, corresponding ionospheric anomalies are also observed in the magneto conjugate region. Potential causes of these results are discussed,eliminating the ionospheric anomalies that may be caused by solar activities and magnetic storms, it can be concluded that the observed obvious anomalous variation in GPS TEC on April 5 were possibly related to the earthquake. 相似文献
7.
In studying the nonlinear electrohydrodynamic stability of solitary wave packets of capillary-gravity waves, in (2+1) dimensions, for dielectric fluids, we found that the complex amplitude of the surface elevation can be described by a nonlinear Schrödinger equation which can be written in the form of a soliton envelope equation. Using the tanh method we get in a very simple way the solitary wave solutions of this equation which we had obtained before by using the Jacobian elliptic functions. 相似文献
8.
On the basis of the geophysical (seismic profiles and electric tomography), geomorphic and geological data, we re-evaluate the post-Pliocene structural interpretation of the southern Upper Rhine graben (Basel–Mulhouse area): we demonstrate a Plio–Pleistocene northward propagation of the Jura thrust and fold belt up to Mulhouse proceeding from a succession of four 10 km apart ramps (from north to south Ferrette, Muespach, Magstatt and Rixheim) rooted within the late Triassic evaporitic marls acting as a decollement. This domain was previously considered as having undergone an on-going continuous extension (horst of Mulhouse bounded by the Quaternary Sirentz and Dannemarie grabens).The Quaternary activity of this thin-skinned tectonics induces the growth of a sedimentary wedge whose regional slope, which comprised between 1.4° and 1° to the north, also attests to a low friction basal detachment. More into details, these ramps correspond to 40–50-m high jumps within the forward topographic slope. Pleistocene activity is suggested just above the Muespach ramp by the presence of a 5–10-m north-facing scarp corresponding in depth to a 3-m vertical offset of early Pleistocene alluvial deposits. Farther to the north, a stronger incision of the Rhine Würm terrace can be interpreted as the result of the growth of the Mulhouse–Rixheim frontal ramp.This northward propagation of the Jura thrust and fold belt is strongly controlled by the Oligocene structural inheritage. The development of the frontal ramp in Mulhouse has to be related to the Oligocene significant vertical offset of the Triassic evaporite along the Mulhouse Railway Station fault preventing a propagation of the decollement farther to the north. In the same way, the fold propagation is laterally segmented by the N20°E trending Oligocene fabrics (from East to West, Rhine Valley flexure fault, Allschwil–Istein fault system and Illfurth fault) which acts above the decollement as lateral ramps. To the west, the development of a shallow anticline along the Illfurth fault suggests that the thin-skinned propagation is oblique with respect to the Oligocene fabrics. It results in spacial contrast between a left-lateral-reverse and a right-lateral–normal shallow kinematics along the western and eastern lateral ramps, respectively. In depth to the east, it also induces a vertical contrast between shallow (right-lateral–normal) and deep (left-lateral given by fault plane solutions) kinematics along the Istein–Allschwill–Rhine Valley fault system.Few arguments supporting a nucleation of the Basel-1356 earthquake, the strongest event in NW Europe in the last thousand years, onto the Rhine Valley fault system beneath the decollement have been given. However, we emphasize that the above mentioned coeval thin (aseismic)- and thick (seismic)-skinned tectonics along the Istein–Allschwill–Rhine Valley fault system would make difficult both the identification and the interpretation of the surface rupture of the Basel-1356 earthquake. 相似文献
9.
10.
Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant G is entirely dimensionfull. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of both Big Bang Nucleosynthesis and recombination in a dimensionless manner. Rigorously determining how to talk about the model in a way which avoids physical dimensions is a requirement for proceeding with a calculation to constrain time-varying fundamental constants. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any one of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding G to the usual cosmological parameter set. 相似文献
11.
In this paper, starting with the Szebehely and Bond (1983) equation, we rediscuss the regularization and linearization of the perturbed planar two-body problem.We study the generalization of the Sundman's (1912) transformation proposed by Szebehely and Bond and obtain the radial and transverse perturbations (represented by powers of the radial distance r), which can be linearized with these transformations. In this way we generalize some previous results of Belen'kii (1981a, b) and Szebehely and Bond (1983).We also consider another generalization of Sundman's transformation, introduced by Cidet al. (1983), in the case when the radial and transverse perturbations are presented by polynomials in the reciprocal of the distance. As a consequence we give a partial answer to a problem suggested by Szebehely and Bond (1983). 相似文献
12.
As a Philippine contribution to the International Heliophysical Year, we propose to use the MAGnetic Data Acquisition System/Circum Pan-Pacific Magnetometer Network (MAGDAS/CPMN), installed by the Space Environment Research Center (SERC), Kyushu University along the 210° magnetic meridian and the magnetic equator, to study the equatorial electrojet (EEJ) and counter electrojet (CEJ). Through this installation, it is made possible to observe geomagnetic field variations in real time. By utilizing this network of ground-based instruments, we hope to elucidate their regular day-to-day and seasonal variabilities and variations during magnetic storms and substorms. We also want to study the behavior of this ionospheric current system before, during, and after the occurrence of an earthquake. 相似文献
13.
《Chinese Astronomy and Astrophysics》1982,6(1):60-63
We discuss the excitation of polar motion by earthquake displacement field. Instead of the usual static equilibrium equations in the literature, we use an improved set as given in /1/, which guarantee continuity at the core-mantle boundary. We take the parameter values of three earthquakes from /2/.To obviate the singularity at r = 0, we use asymptotic solutions by power series within a small sphere around the centre. Outisde this sphere, the equations are numerically integrated by the Runge-Kutta algorithm. Our equations /1/ gave polar shifts some 3 times larger than Dahlen's equations /2/. 相似文献
14.
F. W. Jäger 《Solar physics》1972,27(2):481-488
It is shown in detail in which way magnetographic measurements may be affected by instrumental polarization. To eliminate this influence we propose a combined method of partial compensation and computation practicable successfully with only a moderate expenditure of calculations and instrumental equipment. 相似文献
15.
Study of the Correlations Between Long-Periodic Terrestrial Tides and Occurrence of Earthquakes in the Vrancea Site 总被引：1，自引：0，他引：1
Following studies already performed by various authors concerning specific tectonic faults we analyse statistically the possibility
that earthquakes in the very active seismological zone of Vrancea (Roumania) may be triggered by the vertical luni-solar tidal
oscillations when retaining only the components other than diurnal and semi-diurnal. Our conclusion is that for three of the
four leading tides, with periods 18.6 y, 182.62 d, and 13.66 d, the earthquakes occur preferentially during the ascending
part of each of the sine oscillation. This property is especially visible for the leading 13.66 d fortnightly wave, and for
the 18.6 y wave, for which results are very similar to that of Kilston and Knopoff (1983), who analyzed data related to the
San Andreas fault in Southern California. As a complement, we carried out an analysis of earthquake periodicities w.r.t. the
variation rate of each of the tides above, given by the half-period sine oscillation, which also leads to interesting possible
correlations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Jyh-Woei Lin 《Astrophysics and Space Science》2012,341(2):251-258
Nonlinear principal component analysis (NLPCA) is implemented to analyze the spatial pattern of total electron content (TEC) anomalies 3 hours after Japan’s Tohoku earthquake that occurred at 05:46:23 on 11 March, 2011 (UTC) (M w =9). A geomagnetic storm was in progress at the time of the earthquake. NLPCA and TEC data processing were conducted on the global ionospheric map (GIM) for the time between 08:30 to 09:30 UTC, about 3 hours after this devastating earthquake and ensuing tsunami. Analysis results show stark earthquake-associated TEC anomalies that are widespread, and appear to have been induced by two acoustic gravity waves due to strong shaking (vertical acoustic wave) and the generation of the tsunami (horizontal Rayleigh mode gravity wave). The TEC anomalies roughly fit the initial mainshock and movement of the tsunami. Observation of the earthquake-associated TEC anomalies does not appear to be affected by a contemporaneous geomagnetic storm. 相似文献
17.
S. Selak 《Astrophysics and Space Science》1987,132(1):195-200
In this paper we assert that Einstein's assumption of the validity of special relativity in an infinitely small domain of space-time cannot be accepted if the dilatational degree of freedom exists as a natural key in explaining the existence of gravitation. In this case the equality of inertial and gravitational force holds through the whole structure of space-time but their intensities change continuously by following the behaviour of function which is responsible for reproduction of time and length units from point to point. In addition we discuss the way in which the pseudo-tensor of gravitational field was obtained. 相似文献
18.
19.
20.
In this paper, we conduct a new statistical study on the temporal distribution of the Global Positioning System Total Electron Content (GPS TEC) anomalies prior to the earthquakes with magnitude M≥7.0 in the global area during 2003–2012 by the method of statistical analysis. The temporal distribution of the ionospheric TEC anomalies prior to the earthquakes with magnitude M≥7.0 is for the first time studied. It has been observed that the ionospheric negative anomalies mainly occur in one week prior to the earthquakes, and only when the magnitude is greater than or equal to 7.6, the ionospheric anomalies will have the greatest probability of occurrence in the afternoon to sunset (i.e. between 12:00 and 18:00 local time). They last for approximate 2 hr, but the chance of detecting the significant enhancement in the ionospheric TEC seems not to be a function of time and there is no clear tendency for positive anomalies. In addition, the relationship of the occurrence rate of pre-earthquake ionospheric anomalies and the magnitude of the earthquake is discussed, and it is found that the observed ionospheric TEC anomalies within several days before the earthquakes are highly likely to be related with the earthquakes because the occurrence rate of pre-earthquake ionospheric anomalies seems to increase slightly with the earthquake magnitude increasing. 相似文献