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1.
Yun-Lin Zhang Hai-Jing An Xiao-Ling Liu Yu-Lan Si Mei Jiang Wu-Si Zhang 《地震学报(英文版)》1993,6(3):675-683
The high accuracy, automatic, digital MT measurement system with five electromagnetic components was firstly adopted by the
author to the section MT monitor and measurement in the middle Qilian mountain in the Northwestern China, the more real precursory
information of impending earthquake electromagnetic rediation of GongheM=7.0 earthquake (April, 1990) in Qinghai province was obtained by the system.
The new complete quantification frequency analysis was firstly used in this paper in both time and space domains for the analysis
of repeated measurement data at all sites.
This paper concludes the precursory spectral characteristics of electromagnetic radiation before strong earthquake as following:
1. The spectra appears as the synchronous electric field interference type mainly of conduction current; 2. Narrow band (0.5
– 20s) of spectral period; 3. The singularity of amplitude (the pulse amplitudes of interference electric field is 102 times the normal values); 4. They show the directionality of preparing focus to some extent; 5. The intermittent of radiation
(three peak periods appeared three days before the main shock). It is more significant that there existed a relative quiet
period of about 48 hours between the peak period and the occurrence, observators can response quickly at observational sites
and take it as one of the observational criterions for impending prediction.
This paper also points out that the impending earthquake electromagnetic radiation obtained by the MT measurement system is
mainly the conduction current, and the high-conductive layer existed commonly in the crust may serve as the better paths for
the conduction current circuit and enables the far away MT measurement sites to receive it.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 186–193, 1993. 相似文献
2.
IntroductionShort-to-imminentprecursorsstillarethemainbasisforearthquakepredictioninthepresenttime.Strongquakes,especiallythosewithnoforeshocks,canbeforecastedtosomeextentbasedonabundantshoat-to-imminentprecursorsandcombiningwiththemid-to-longtermvar... 相似文献
3.
Mingzhi Yang 《地震学报(英文版)》1992,5(4):719-728
In this paper, considering the influences of source spectrum, the scattering property of medium and instrument response on
the dominant frequency of coda, a method of using the coda of local earthquake to determine the correlation length of medium
andQ-value is given. We find the following formula as: {fx719-1} wheret* =t/Q, f is the dominant frequency of coda,u
1 andu
2 are the parameters depend on the correlation length and the corner frequency of the source spectrum respectively,I(f) is a function of instrument response. If the source parameter is given, we can obtain the correlation length andQ-value by means of the inversion of observed curves off-t of coda. We processed the data of coda wave of more than 40 earthquakes from 1982 to 1989 in Lingwu region, China, determined
the correlation length andQ-value, and preliminarily studied the temporal change of correlation length before and after moderately strong earthquakes.
The result suggests that there are indications that the correlation length of medium decreases before the moderate earthquake.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 62–70, 1992. 相似文献
4.
In this paper, the MYCIN inexact inference method in Expert System is applied to comprehensive earthquake prediction. And
it is proposed that the methods of determining various certainty factors, correcting correlation between anomalous evidences
and computing comprehensive certainty factor of occurrence of some moderate or strong earthquake. By use of these methods,
18 earthquake cases since 1966 in North China is tested with seismological anomalies in different seismogenic stage, and the
comprehensive certainty factors of occurrence of some moderate or strong earthquake are computed. At last some problems in
application are discussed.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 328–337, 1991. 相似文献
5.
In this paper we study the S wave basement velocity structure and S wave splitting and polarization anomalies using the three
component records of deep seismic sounding in the Three Groges Dam area, and further discuss the methods to study the anisotropy
of crustal medium, the direction of regional tectonic stress field, and the physical indicator of potential earthquake sources
using shear wave splitting and polarization anomalies. It has been demonstrated by analyzing the DSS data in the Three Gorges
Dam area that S wave splitting and polarization anomalies are reliable means for studying seismic anisotropy of crustal medium
and the direction of regional tectonic stress field. At the same time, it has been shown that DSS data are very useful for
widening S wave observing window and distinguishing anomalous body, because DSS data have the advantage that the source position
is known prior and S wave ray path can be traced exactly.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 1–3, 1993. 相似文献
6.
Since 1979 the repeated observations and experiments of geomagnetic total intensity and vertical component have been carried
out for ten years in the geomagetic network which is located in Jiangsu Province, China. Three earthquakes aboveM
s 5.0 occurred during the decade, and some seismomagnetic effects were observed. The observation results show that the anomalies
of the vertical geomagnetic component can’t be observed untill some months before the earthquake (M
s>5.0) in this area.
In this paper it is suggested that a densely distributed network for continuous observation of geomagnetic vertical component
may catch seismomagnetic anomalies and thus improve earthquake prediction in the light of the geomagnetic measurements of
the mid — or — low latitude locations.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 80–87, 1991.
This study is sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
7.
Observations and studies of electromagnetic waves during the approaching of earthquakes 总被引:1,自引:0,他引:1
This article introduces the practical observation results of pre-earthquake electromagnetic radiations at the network of monitoring
stations in Jiangsu region in resent years and discusses the electromagnetic wave precursors during the approaching period
of earthquakes based on the observations of the electromagetic radiation signals before theM
s 6.0 Liyang earthquake of 1979 in Jiangsu province, theM
s 5.9 Heze earthquake of 1983 in Shandong province and theM
s 6.2 South Yellow Sea earthquake of 1984. 相似文献
8.
Based on Generalized Seismic Ray Theory (Helmberger, 1968), a new quickly linear inversion method from the data of seismic
waveform to seismic moment tensor and source mechanism for domestic earthquake is studied in this paper. Six moderately strong
earthquakes which occurred in Chinese mainland in the past few years are studied. The seismic source parameters of these earthquakes,
seismic moment tensors, scalar seismic moments, fault plane solutions and source time functionsetc, are obtained.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 261–268, 1993. 相似文献
9.
Hao Xiong 《地震学报(英文版)》1992,5(2):407-412
The paper briefly reviews the recent advances and the main trend, as well as the major subjects for future study in the research
on seismo-electromagnetic emissions. The preliminary results obtained show that the recently discovered electromagnetic emission
phenomena prior to earthquake events are objective facts and may be prospective precursor applicable for short term earthquake
prediction. Considering the complexity of the generation mechanisms, as well as the space coupling and the time variation
processes of the seismo-electromagnetic emissions, we must deeply study the essential connection between the precursory emission
phenomena and the seismogenic processes. Closely connect the field observations and theoretical research and try to comprehensively
diagnose by correlating with other precursors.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 254–258, 1991. 相似文献
10.
The diurnal-variation anomalies of the vertical-component in geomagnetic field are mainly the changes of phase and amplitude
before strong earthquakes. On the basis of data recorded by the network of geomagnetic observatories in China for many years,
the anomalous features of appearance time of the minima of diurnal variations (i.e, low-point time) of the geomagnetic vertical components and the variation of their spatial distribution (i.e, phenomena of low-point displacement) have been studied before over 30 strong earthquakes with M
S≥6.6 such as Kunlunshan M
S=8.1 earthquake on November 14, 2001; Bachu-Jashi M
S=6.8 earthquake on February 24, 2003; Xiaojin M
S=6.6 earthquake on September 22, 1989, etc. There are good relations between such rare phenomena of geomagnetic anomalies and the occurrence of earthquakes. It has
been found that most earthquakes occur in the vicinity of the boundary line of sudden change of the low-point displacement
and generally within four days before and after the 27th or 41st day counting from the day of appearance of the anomaly. In
addition, the anomalies of diurnal-variation amplitude near the epicentral area have been also studied before Kunlunshan M
S=8.1 earthquake and Bachu-Jiashi M
S=6.8 earthquake.
Foundation item: National Science Technology Tackle Key Project during the Tenth Five-year Plan (2001BA601B01-05-04) 相似文献
11.
12.
The Earth's natural pulse electromagnetic fields for earthquake time–frequency characteristics: Insights from the EEMD–WVD method
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Monitoring the Earth's natural pulse electromagnetic field (ENPEMF) signal is a geomagnetic detection approach for the Earth internal and external studies, and it provides a reference for earthquake prediction. In this paper, the Ensemble Empirical Mode Decomposition–Wigner Ville Distribution (EEMD–WVD) method is used to process the time sequences of the ENPEMF signal detected by GR‐01 receiving devices during the Lushan MS7.0 earthquake (April 20th, 2013). By obtaining the intrinsic mode function (IMF), the time–frequency–amplitude joint distribution and the energy spectrum of the ENPEMF signal, the suspected anomalies before the earthquake could be shown. The results illustrate the ENPEMF signal before an earthquake and its time–frequency characteristics based on an EEMD–WVD algorithm, proving useful information about the anomalies around the time of the earthquake. 相似文献
13.
The digital seimograph network set up by China and France in Zhangye of China had been operated in 1988. The Zhangye network
is situated in the middle segment of Hexi corridor and Qilina mountain, which was regarded as a monitoring earthquake area.
Using the records of Zhangye digital network theQ-values in and around Minle basin have been measured. The results of this study showed that theQp-values range from 500 to 780, andQs-values range from 230 to 460. TheQ-values of inside of Minle basin are higher than that around the basin. The greater parts of moderate and strong earthquakes
occurred along tectonic belts around the Minle basin. Moreover, TheQ-values increased with the depth of penctration of wave ray. The attenuation of S wave is stronger than P wave in shallow
layer of crust. Some problems ofQ-value change versus time before and after Sunan eathquake (M
s=5.7) have been also disscussed. These results can be applied to study and to monitor seismic danger of the Minle monitoring
area.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 296–302, 1993. 相似文献
14.
Based on fracture mechanics, large amount of practically observed data is analyzed in this paper, and it is disclosed that
seismically-anomalous earthquake resistivity sudden change sequence can be observed at the earth resistivity stations around
the epicenter of a strong event. The maximum sudden change in the sequence tends to shift backward with the increase of epicentral
distance, while it shifts forward with the increase of the magnitude of the earthquake. The maximum sudden change also expands
from the epicenter to the peripheral areas. Therefore, the authors propose that it might be possible to predict the 3 key
elements of a forthcoming earthquake by using the sudden change sequence, the frequency of the sudden change, the expansion
velocity of the maximum sudden change and the time-distance product.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 176–185, 1993. 相似文献
15.
基于高光谱遥感数据,通过RST算法提取2020年7月12日唐山5.1级地震前不同参数异常信息,发现震前CH4、CO、H2O、O3均出现了高值异常,且异常均位于震中附近,异常幅度高于2倍均方差,CH4、CO、H2O异常机理不同于O3。通过统计2018—2020年CH4、CO、H2O三种气体出现频次,发现同步异常具有可靠性,认为高光谱多参数异常出现的同步性,可提高异常性质判定的信度。通过对不同参数进行连续跟踪观测,提取多参数同步异常信息,对地震短临预报具有一定参考意义。 相似文献
16.
Empirical scaling equations for Fourier amplitude spectra of strong ground motion are used to describe A0 and τ in the assumed (high-frequency) shape of strong motion amplitudes: FS(φ) = A0e-πτφ. The res of computed A0 and τ with other related estimates of spectral amplitudes; (2) smooth decay of strong motion spectral amplitudes up to φ = 25 Hz, without an abrupt low-pass filtering of high frequecies; and (3) good agreement with other estimates of the regionally specific attenuation of high-frequncy seismic waves.As the recorded strong earthquake shaking in the western United States typically samples only the shallow (10 km) and local (100km) characteristics of wave attenuation, the processed strong motion accelerograms can be used as the most direct means of describing the nature of the high-frequency attenuation of the entire strong motion signal for use in earthquake engineering applications. Seismological body wave, Lg and coda wave estimates of Q sample different volumes of the crust surrounding the station, and involve different paths of the waves. These differences must be carefully documented and understood before the results can be used in earthquake engineering characterization of strong motion amplitudes. 相似文献
17.
为了研究2014年鲁甸MS6.5、景谷MS6.6地震前的长波辐射变化特征,应用功率谱相对变化法,以风云气象卫星长波辐射资料为基础数据,对上述2次地震进行了分析。结果显示:2次地震前短期内均存在明显的长波辐射相对功率谱异常变化,异常特征展布的边缘及走向与断层密切相关,震前短期内地震当年功率谱明显偏离其背景值及标准差,偏离持续时间约2个月,最大偏离差在7倍以上。2014年云南地区的这2次6级以上地震所表现出的长波辐射时空异常特征明显,易于识别,可为长波辐射资料用于该地区的地震监测提供震例经验。 相似文献
18.
Ionospheric electromagnetic perturbations observed on DEMETER satellite before Chile M7.9 earthquake
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Xuemin Zhang Jiadong Qian Xinyan Ouyang Xuhui Shen Jin an Cai Shufan Zhao 《地震科学(英文版)》2009,22(3):251-255
Based on the ionospheric electromagnetic data observed on DEMETER satellite of France, the ionospheric electromagnetic signals were analyzed within 10 days before Chile M7.9 earthquake on November 14, 2007. It is found that, low frequency electromagnetic disturbances began to increase in a large scale of latitude, and reached to a maximum one week prior to the earthquake, and at about three days before the quake, the peak values shifted to lower latitude. Taking three days as a group, spatial images of a few parameters were analyzed, from which it can be seen during the five days prior to this earthquake, the amplitude and scale of anomalies are enlarged, while the epicenter is located at the boundary of anomalous region. The anomalous tempo-spatial variation in electron density prior to the earthquake were also obtained in terms of tracing the data from revisited orbits in half a year prior to the quake. 相似文献
19.
In this paper, the methods of pattern recognition and fuzzy cluster are applied to estimate comprehensive whether there would
be an earthquake which magnitude is commensurate with (N=M
0±0.3) or greatM>M
0) thanM
0 within 3 months using sequential data in 3 days immediately after a moderate or strong earthquake (M
0≥4.7) occurred, The result of retrospective test indicates that the comprehensive judgment effects by using these applied
mathematics methods are better than that of using every individual method obviously. TheV mark value of algorithm CORA-3 in pattern recognition is the highest among them. There are 44 known earthquake sequence data
(5 type- I and 39 type- II) used to learn and train, the results of internal coincidence test show that all 44 sequence samples
could be distinguished correctly. Extrapolation test by using other 4 known earthquake sequences (2 type- I and 2 type- II)
shows that all 4 extrapolation samples could be distinguished correctly also. In the process of study, these methods have
been applied to judge the post-earthquake tendency of 2 moderate earthquakes occurred recently, one is distinguished correctly
and the other wrong. The algorithm Hamming in pattern recognition and fuzzy cluster method have been applied to judge the
early post-earthquake tendency after a moderate or strong earthquake, too. TheV mark values of internal coincidence tests could get above 0.8 most cases of extrapolating are correct.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 15–21, 1993. 相似文献
20.
Mei-Xiang Bai Ke-Yuan Wang Jing-Yuan Liu Xiao-Dan Sun Wen-Zhuang Shen Aerkuat Nurmakambeitov A. Seidekov V. A. Jaibig A. A. Vlacova A. Toseimov 《地震学报(英文版)》1993,6(4):1041-1047
The Zaisang earthquake (M
s=7.3) on June 14, 1990 occurred in the boundary between China and Kazakstan. During the great shock, 3 persons lost their
lives, 30 people had been hurt and 340 houses collapsed. The intensity of the epicentre is VIII Degree. The economic losses
equals to about 320 000 000 Yuan. This large earthquake was occurred on a new born fault, it belongs to main shock-aftershock
type earthquake.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 360–365, 1993. 相似文献