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1.
Based on the time series of observational variations of the length of day (LOD) and seismic data in the world, the relations of the decadal fluctuation and seasonal variation in the Earth’s rotation with global seismic activity are studied in this paper. The results suggest that there are overall correlations on temporal scale and regional discrepancy on spatial scale between global seismic activity and the Earth’s variable rotation, especially the seismic activity in the Eurasian seismic zone (not including southeast Asia) and the Lower California-Eastern Alaska seismic zone correlating well with the Earth’s variable rotation. According to the relations mentioned above, the observational data of the Earth’s rotation might provide a referential basis for monitoring global seismic activity. 相似文献
2.
ＲｅｓｅａｒｃｈｏｎｔｈｅｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎＥａｒｔｈ＇ｓｖａｒｉａｂｌｅｒｏｔａｔｉｏｎａｎｄｇｌｏｂａｌｓｅｉｓｍｉｃ ａｃｔｉｖｉｔｙＤａ－ＷｅｉＺＨＥＮＧａｎｄＹｏｎｇ－ＨｏｎｇＺＨＯＵ（郑大伟，周永宏）（Ｓｈａｎｇｈａｉ... 相似文献
3.
The 2008 Wenchuan earthquake occurred in an active earthquake zone, i.e., Longmenshan tectonic zone. Seismic waves triggered
by this earthquake can be used to explore the characteristics of the fault rupture process and the hierarchical structure
of the Earth’s interior. We employ spectral element method incorporated with large-scale parallel computing technology, to
investigate the characteristics of seismic wave propagation excited by Wenchuan earthquake. We calculate synthetic seismograms
with one-point source model and three-point source model respectively. The AK135 model is employed as a prototype of our numerical
global Earth model. The Earth’s ellipticity, Earth’s medium attenuation, and topography data are taken into consideration.
These wave propagation processes are simulated by solving three-dimensional elastic wave governing equations. Three-dimensional
visualization of our numerical results displays the profile of the seismic wave propagation. The three-point source, which
is proposed from the latest investigations through field observation and reverse estimation, can better demonstrate the spatial
and temporal characteristics of the source rupture process than the one-point source. We take comparison of synthetic seismograms
with observational data recorded at 16 observatory stations. Primary results show that the synthetic seismograms calculated
from three-point source agree well with the observations. This can further reveal that the source rupture process of Wenchuan
earthquake is a multi-rupture process, which is composed by at least three or more stages of rupture processes.
Supported by National Basic Research Program of China (Grant No. 2004CB418406), National Natural Science Foundation of China
(Grant Nos. 40774049 and 40474038), and Computer Network Information Center, Chinese Academy of Sciences (Grant No. INF105-SCE-02-12) 相似文献
4.
The studies on the structure and physical properties of the Earth‘s interior done by Chinese geophysicists from 1999 to 2002 were reviewed in this paper. It includes several research areas: the structure of the Earth‘s interiors using seismic tomography, anisotropy of the upper mantle in China and its adjacent areas, quality factor Qβ for S waves, subduction zone, mantle discontinuities, physical properties of Earth‘s materials and others. The review concerns mainly the contents, the methods and the results of the studies. It can be seen that new progress in the study on the structure and physical properties of the Earth‘s interior has been made in the last 4 years in China. It is shown on three aspects: advancement made on some preexistent areas; pioneering on some new fields and new methods adopted. 相似文献
5.
M. I. Yaroshevich 《Izvestiya Physics of the Solid Earth》2011,47(7):636-640
A possible influence of tropical cyclones on seismic activity in the cyclonic zone of the northwestern Pacific is considered.
There is no direct and sufficiently reliable method for calculating the degree of impact of tropical cyclones on the Earth’s
crust. Therefore, a sort of inverse problem is solved in the investigation: a possible qualitative influence of tropical cyclones
on seismic activity is estimated from its intra-annual dynamics. It is established that for territories of the cyclonic zone,
the intra-annual dynamics of cyclonic and seismic activities are similar. Low monthly mean values of the cyclonic and seismic
energies are attained in July–October, whereas in the continental territories under consideration (Central Asia), the seismic
activity is higher in January–March. The results obtained suggest that cyclones can affect the seismic regime in the cyclonic
zone of the northwestern Pacific. 相似文献
6.
The synthetic tidal parameters with high spatial resolution for gravity over China and its neighbor area are con- structed with Earth’s tidal model and ocean tide loading calculated using TPXO7 global ocean tide model as well as tidal data over China seas. The comparison between synthetic parameters and ones observed by spring gravime- ters at some seismic network stations and Hong Kong station and one observed by super-conducting gravimeter at Wuhan station shows that the average differences in amplitude factors and phases are smaller than 0.005 and 0.5° respectively; and that the discrepancies between observational and synthetic parameters are dependent on gravim- etric technique in that the synthetic parameters are in well agreement with the superconducting gravimetric obser- vations. This also indicates that the synthetic result is a good estimation for tidal gravity, and the numerical results in the present paper not only can provide ground and space gravimetry such as absolute gravimetry with correction model of tidal gravity, but also provide effective tidal parameters over areas where no observation is carried out. 相似文献
7.
V. P. Antonova N. N. Volodichev S. V. Kryukov A. P. Chubenko A. L. Shchepetov 《Geomagnetism and Aeronomy》2009,49(6):761-767
The unit for detecting thermal neutrons, which makes it possible to study variations in cosmic rays of the interplanetary
and geophysical origin, has been created at the high altitude cosmic ray station (3340 m above sea level) near the Earth’s
crust fault. It has been established that variations in thermal neutrons are of the same nature as high-energy variations
registered with a neutron supermonitor in the absence of seismic activity. The flux of thermal neutrons from the Earth’s crust
during seismic activity in December 2006 has been registered for the first time. The flux value is higher than the background
level by 5–6%. The method for detecting the flux of thermal neutrons from the Earth’s crust with the simultaneous registration
of high-energy neutrons has been proposed. 相似文献
8.
Besides generating seismic waves, which eventually dissipate, an earthquake also generates a static displacement field everywhere within the Earth. This global displacement field rearranges the Earth’s mass thereby causing the Earth’s rotation and gravitational field to change. The size of this change depends upon the magnitude, focal mechanism, and location of the earthquake. The Sumatran earthquake of December 26, 2004 is the largest earthquake to have occurred since the 1960 Chilean earthquake. Using a spherical, layered Earth model, the coseismic effect of the Sumatran earthquake upon the Earth’s length-of-day, polar motion, and low-degree harmonic coefficients of the gravitational field are computed. Using a model of the earthquake source that is composed of five subevents having a total moment-magnitude M
w
of 9.3, it is found that this earthquake should have caused the length-of-day to decrease by 6.8 microseconds, the position of the Earth’s generalized figure axis to shift 2.32 milliarcseconds towards 127° E longitude, the Earth’s oblateness J
2 to decrease by 2.37 × 10−11 and the Earth’s pear-shapedness J
3 to decrease by 0.63 × 10−11. The predicted change in the length-of-day, position of the generalized figure axis, and J
3 are probably not detectable by current measurement systems. But the predicted change in oblateness is perhaps detectable if other effects, such as those of the atmosphere, oceans, and continental water storage, can be adequately removed from the observations. 相似文献
9.
S. I. Boldyrev O. P. Kolomytsev G. S. Ivanov-Kholodny A. P. Ignatyev 《Geomagnetism and Aeronomy》2009,49(8):1278-1282
The present-day models of the Earth’s upper atmosphere make it possible to construct the spatial-temporal pattern of variations
in the atmospheric parameters on the planetary scale in essence in the averaged form. The set of data on the satellite deceleration
in the atmosphere, probe measurements aboard geophysical rockets, and radiowave incoherent scatter measurements in the Earth’s
atmosphere are used to construct these standard models. The current level of the space studies makes it possible to use a
new method to study the Earth’s upper atmosphere: to study the upper atmosphere by measuring the absorption of the solar XUV
radiation by the Earth’s atmosphere during the solar disk observations. 相似文献
10.
Sumatra-Andaman Large Earthquake on Dec. 26, 2004 generated not only the Indian Ocean Tsunami but also the Earth’s free oscillations
(EFO). The signals of Earth’s free oscillations were perfectly recorded by the superconducting gravimeter C0-32 at Wuhan station
in China. After the pre-treatment and spectral analysis on the observational data from Wuhan station, we obtained more than
ninety EFO modes including 42 fundamental modes, 2 radial modes and 49 harmonic modes. On the basis of the discussions on
some observed harmonic modes and abnormal splitting phenomena, we considered that the real rigidity might be lower than the
theoretical prediction of PREM model in the inner core and however the anisotropy of compressive wave was brightly higher
than the present estimations in the inner core. This suggested that the anisotropy of the inner core could be much more complicated
than our present understanding, and there might be some new geophysical phenomena in the formation process of the inner core.
Supported jointly by the National Natural Science Foundation of China (Grant Nos. 40404005 and 40374029) and the Excellent
Prize of President Scholarship and Hundred Talents Program of the Chinese Academy of Sciences 相似文献