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1.
According to geological tectonics and seismic activites this paper devided North China (30°–45°N, 105°–130°E) into four areas. We analyzed the North China earthquake catalogue from 1970 to 1986 (from 1965 to 1986 for Huabei, the North China, plain region) and identified forty-two bursts of aftershock. Seven of them occurred in aftershock regions of strong earthquakes and seventeen of them in the seismic swarm regions. The relation between strong earthquakes with the remaining eighteen bursts of aftershocks has been studied and tested statistically in this paper. The result of statistical testing show that the random probabilityp of coincidence of bursts of aftershock with subsequent strong earthquakes is less than six percent. By Xu’sR scoring method the efficacy of predicting strong earthquake from bursts of aftershock is estimated greater than 39 percent. Following the method proposed in the paper we analyzed the earthquake catalogue of China from 1987 to June, 1988. The results show that there was only one burst of aftershock occurred on Jan. 6, 1988 withM=3.6 in Xiuyan of Northeast China. It implicates that a potential earthquake withM S⩽5 might occur in one year afterwards in the region of Northeast China. Actually on Feb. 25, 1988 an earthquake withM S=5.3 occurred in Zhangwu of Northeast China. Another example is Datong-Yanggao shock on October 18, 1989 which is a burst of aftershock. Three hours after an expected shock withM =6.1 took place in the same area. Two examples above have been tested in practical prediction and this shows that bursts of aftershocks are significant in predicting strong earthquakes. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 273–280, 1991. Part of earthquake catalogue is from Jinbiao Chen, Peiyan Chen and Quanlin Li.  相似文献   

2.
ＴｈｅｒｅｇｉｏｎａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｓｅｉｓｍｉｃａｃｔｉｖｉｔｙｉｎＣｈｉｎａＺｈｅｎ－ＬｉａｎｇＳＨＩ，ＪｉａｎＷＡＮＧａｎｄＸｉａｏ－ＤｏｎｇＺＨＡＮＧ（时振梁，王健，张晓东）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，Ｓ...  相似文献   

3.
In this paper, one of the distribution-free tests — randomization test, is briefly described. It doesn’t need any distribution assumption and its related parameter estimation and is applicable to random and nonrandom sample. Then it is used to the test of migration of strong earthquakes on the Xianshuihe Fault Belt and “immunity” of large earthquakes in the large northern reigon of China. The test results show that there is 98.7% confidence degree for the migration of strong earthqueks on the Xianshuihe Fault Belt and “immunity” of earthqueks withM S⩾8 toM S⩾7 is significant in the large northern region of China. The obtained test results and the test method itself have certain application in the practice. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 484–489, 1993.  相似文献   

4.
This paper has introduced the method of self-similarity analysis of time series into the analysis and study of earthquake sequence, and then researched its application in earthquake prediction. As parameter of earthquake time series, we can take the cumulated sum of the numbers of equivalent earthquakesQ=ΣN*, the numbers of equivalent earthquakeN*, maximum magnitudeM max, average magnitudeQ=ΣN*, and the difference ΔN* between the numbersN* in two adjacent time intervals. The given method may be applied to analysis of long-period seismic sequences in different regions as well as to anlysis of seismic sequence in the aftershock region of strong earthquake. For making quantitative analysis the coefficient of self-similarity of earthquake sequence in order of timeμs was introduced. The results of self-similarity analysis were obtained for the earthquake sequences in North China, West South China, the Capital region of China, and for the East Yamashi region of Japan. They show that in period or half year to several years beforeM⩾7.0 andM⩾6.0 earthquakes occurred in these regions separately, the self-similarity coefficientμs calculated by using the above-mentioned parameters had remarkably anamalous decrease variations. The duration time ofμs anomaly depends on the earthquake magnitude and may be different from different regions. Therefore, the self-similarity coefficient in order of timeμs can be considered as a long-medium term precursory index. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 455–462, 1993.  相似文献   

5.
To actually reflect the seismic temporal-spatial inhomogeneity of intra continental strong earthquakes of North China in seismic hazard analysis, several seismological and geological characteristics have been selected and quantized to describe the seismicity features in time and space of every magnitude interval with the thought of dividing the interesting magnitude range into several intervals and using of spatial probability distribution function. A component analysis method with orthogonal transformation is introduced to avoid the repeated use of the same element and the subjective effects in determining the annual earthquake occurrence rates of earthquake. By passing synthetic fuzzy judgement on the nonintercorrelated new characteristics, the annual occurrence rates of every magnitude interval of each potential source area are obtained associated with the adjustments of earthquake reducing process after the occurrence ofM>7 quake. An intensity map of the Beijing-Tianjin-Zhangjiakou area is calculated as an example which shows a close coincidence with the seismic temporal-spatial inhomogeneity of North China. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 496–504, 1991.  相似文献   

6.
ＧｒｏｕｐｉｎｇｏｃｃｕｒｒｅｎｃｅｓｂｅｉｎｇｔｈｅｆｕｎｄａｍｅｎｔａｌｆｅａｔｕｒｅｏｆｔｈｅｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓｉｎＣｈｉｎｅｓｅｍａｉｎｌａｎｄＱｉｎ－ＺｕＬＩ（李钦祖）；Ｌｉ－ＭｉｎＹＵ（于利民）；Ｊｉ－ＹｉＷＡＮＧ（王吉易...  相似文献   

7.
The method of relative seismic moment tensor determination proposed byStrelitz (1980) is extended a) from an interactive time domain analysis to an automated frequency domain procedure, and b) from an analysis of subevents of complex deep-focus earthquakes to the study of individual source mechanism of small events recorded at few stations.The method was applied to the recovery of seismic moment tensor components of 95 intermediate depth earthquakes withM L=2.6–4.9 from the Vrancea region, Romania. The main feature of the obtained fault plane solutions is the horizontality ofP axes and the nonhorizontal orienaation ofT axes (inverse faulting). Those events with high fracture energy per unit area of the fault can be grouped unambiguously into three depth intervals: 102–106 km, 124–135 km and 141–152 km. Moreover, their fault plane solutions are similar to ones of all strong and most moderate events from this region and the last two damaging earthquakes (November 10, 1940 withM W=7.8 and March 4 1977 withM W=7.5) occurred within the third and first depth interval, respectively. This suggests a possible correlation at these depths between fresh fracture of rocks and the occurrence of strong earthquakes.  相似文献   

8.
IntroductionMaximumentropyspectralmethod(MEM)(Burg,1972)hadbeenamethodusuallyusedinstudyingtheseismicityanditsmainpurposeistofindthedominantspectrainthelong-termseismicityprocessesinthepastyears(Zhu,1985).Inthispaper,themethodisappliedtostudywhethertherearesomespecialspectraofseismicityinsomespecificstagesinearthquake-generatingprocesses.Sowestudyseparatelythenormalandabnormalstageofearthquakeactivity,whoseactiveprocessisregardedasstablestochasticprocess,inordertofindtheirspectracharactersan…  相似文献   

9.
ＣｏｍｐｒｅｈｅｎｓｉｖｅａｎａｌｙｓｅｓｏｆｓｅｉｓｍｉｃｓｏｕｒｃｅｌａｙｅｒｉｎＸｉｎｇｔａｉａｎｄＴａｎｇｓｈａｎｓｅｉｓｍｉｃｒｅｇｉｏｎｓａｎｄｔｈｅｃｏｎｄｉｔｉｏｎｓｏｆｍｅｄｉａａｂｏｖｅａｎｄｂｅｌｏｗｔｈｉｓＬａｙｅｒＴＯＮＧ...  相似文献   

10.
We have employed 10 digital records and computed the spectral magnitude and the seismic radiated energy for 18 large earthquakes (M s≥6) occurred in Eur-asian belt during 1986–1989. The nine digital stations (CD-SN) distribute all over China and one in Germany. The spectral magnitudes of various period have different stability among stations. The stability is better for maximum spectral magnitudemi and seismic radiated energyE, their differences among stations are smaller, especially for the stations where the ray path main penetrates the low mantle. But the stability of corner period is usually not good. The relation between seismic radiated energy and seismic moment magnitudeM w is lg (E)=1.5Mw+c, wherec is a constant. The maximum spectral magnitudemi=M w+0.1, it is consistant with theoretical prediction. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 418–426, 1993. This work supported by the Deutsche Forschungsgemeinschaft, Bonn, F. R. Germany. The support is grateful acknowledge.  相似文献   

11.
According to the fact that the Xinfengjiang reservoir earthquakes are caused mainly by water seepage, this paper using the data ofM s⩾2. 0 earthquakes, studies the hydraulic diffusivity of the mainshock zone by the expansion of the distribution area of epicenters. It is indicated thatin-situ hydraulic diffusivity during the preshock activity of the Xinfengjiang reservoir region was about 6. 2 m2/s. However, after the main shock, thein-situ hydraulic diffusivity in the main shock region increased by fifty percent, that is to say, to 9. 7 m2/s. During the long period after main shock occurrence thein-situ hydraulic diffusivity was affected by significant anisotropy of the medium and fluctuation of water level. No regularity can be found. In addition, we compare the diffusivity found by experiment with rock samples collected with thein-situ hydraulic diffusivity estimated. It is shown that the diffusivity of rock samples with fractures is about the same as the diffusivity estimatedin-situ. However, the diffusivity of whole rock samples is 3 orders of magnitudes smaller than that estimatedin-situ. Finally, we discuss the limits on the method by the expansion of distribution area of epicenters in the study of reservoir induced seismicity. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 364–371, 1991. This subject is sponsored by the Chinese Joint Seismological Science Foundation.  相似文献   

12.
Introduction The characteristics of generalized foreshock and direct foreshock and their identification,as well as their application to medium and short-term prediction of strong earthquake is a major study objective in seismometry both in China and abroad.China has made many short-term and imminent earthquake predictions.Among the ones with clear hazard-mitigating effect and social manifestation,direct foreshock has made an obvious contribution,for example,the MS=7.2Menglian earthquake occu…  相似文献   

13.
A great earthquake of M S=8.1 took place in the west of Kunlun Pass on November 14, 2001. The epicenter is located at 36.2°N and 90.9°E. The analysis shows that some main precursory seismic patterns appear before the great earthquake, e.g., seismic gap, seismic band, increased activity, seismicity quiet and swarm activity. The evolution of the seismic patterns before the earthquake of M S=8.1 exhibits a course very similar to that found for earthquake cases with M S≥7. The difference is that anomalous seismicity before the earthquake of M S=8.1 involves in the larger area coverage and higher seismic magnitude. This provides an evidence for recognizing precursor and forecasting of very large earthquake. Finally, we review the rough prediction of the great earthquake and discuss some problems related to the prediction of great earthquakes.  相似文献   

14.
Near-field records of two strong aftershocks with magnitudeM S=6.7 andM S=6.3 in the Lancang-Gengma earthquakes sequence, Yunnan Province, November 1988, are used to calculate the response spectrum. The instruments, site conditions and the methods for computing are also illustrated in this paper. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 338–343, 1991. This project is supported by The Chinese Joint Seismological Science Foundation, SSB and the West Yunnan Earthquake Prediction Test Field, Yunnan Seismological Bureau.  相似文献   

15.
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   

16.
By the mathematical simulation of geotemperature field, deep quasi-stable thermal state and shallow thermal characteristics are reproduced in Sanjiang region of Yunnan. Faults are treated in two ways, 1) as constant heat source in terms ofq=μτ, that is, the quantity of frictional generated heat is constant, in order to simulate frictional heat generated by fault moving; 2) as heat conduits with high thermal conductivities to simulate such a phenomenon that there exist thermal fluids (for example, magma) in fault zones during tectonic movement. And then, through the simulation of thermal stress, the quantity (several bars to hundred bars) and the pattern of thermal stress vectors are obtained, which provides a new clue to the explanation and prediction of earthquakes. And larger tensional and shear stresses occur where the variation of geotemperature and the thickness of thermal lithosphere gradient belt. The stresses are concentrated in the temperature gradient belt. The shear belts of studied area are temperature gradient belts where the variation of the lithosphere thickness is larger and deep heat flow is high and thermal stresses concentrated. All of these may explain the facts that most of the earthquakes, hot springs occur along the fault zones. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 313–321, 1993. The study was financially supported by Chinese Natural Sciences Funds Item Ancient Tethys Tectonic Evolution in Western Yunnan and by centre for Remote sensing, Ministry of Metallurgy.  相似文献   

17.
In the light of the single scattering model of coda originating from local earthquakes, and based on the aftershock coda registered respectively at the 4 short period stations installed near the foci shortly after theM7.6 Lancang andM7.2 Gengma earthquakes, this paper has tentatively calculated the rate of amplitude attenuation and theQ c-value of the coda in the Lancang and Gengma areas using a newly-founded synthetic determination method. Result of the study shows the rate of coda amplitude attenuation demonstrates remarkable regional differences respectively in the southern and northern areas. The southern area presents a faster attenuation (Q c=114), whereas the northern area shows a slower attenuation (Q c=231). The paper also discusses the reasons causing such differences. Result of the study also suggests a fairly good linear relation between the coda source factorA o(f) and the seismic moment and the magnitude. Using the earthquake scaling law, the following formulas can be derived: lgM 0=lgA 0(f)+17.6,M D=0.67lgA 0(f)+1.21 and logM 0=1.5M D+15.79. In addition, the rates of amplitude attenuationβ s andβ m are respectively calculated using the single scattering and multiple scattering models, and the ratioβ s/βm=1.20−1.50 is found for the results respectively from the two models. Finally, the mean free pathL of the S-wave scattering in the southern and northern areas are determined to be 54 km and 122 km respectively by the relations which can distinguish between the inherentQ i and scatteringQ s, testify to this areas having lowQ-values correspond to stronger scatterings. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 71–82, 1992. This study is partly supported by the Seismological Science Foundation of the State Seismological Bureau of China, and the present English version of the paper is translated from its Chinese original by Wenyi Xia, Seismological Bureau of Yunnan Province.  相似文献   

18.
    
By studying the seismicity pattern before 37 earthquakes withM⩾6.0 in North China and the pattern of crustal deformation in the Capital Area from 1954 to 1992, some abnormal characteristics of these patterns before strong earthquakes have been extracted. A comparison has been made between the anomalies of these two kinds of patterns. From the results we can know the following. (1) Before a strong earthquake, the seismicity will strengthen and the crustal deformation rate will increase. (2) Several years before a strong earthquake, there will be seismic gaps and deformation gaps around the epicenter of the quake. (3) The dynamic parameters of patterns all show a decrease in information dimension. This means that the crustal deformation has become more and more localized with time and it gives an important indication showing that a strong earthquake is in preparation. At the end of the paper, the physical mechanisms of the abnormal patterns of seismicity and crustal deformation have been explained in a unified way in terms of the earthquake-generating model of a inhomogeneous strongbody in inhomogeneous media.  相似文献   

19.
The earthquakes offshore Fujian and Guangdong Provinces concentrated along the two segments near Nan’ao in the south and Quanzhou in the north of the off coast fault, which is very active since the late Pleistocene. In 1918 and 1906, two earthquakes with magnitudes 7.3 and 6.1 respectively occurred in the south and the north regions. With the instrumentally determined seismic parameters of these two earthquakes as standards, the author evaluated the parameters of the historical earthquakes by comparing their macroseismic materials with consideration of the geological background. As a result, chronological tables of historical earthquakes of the south and the north regions were compiled. The seismic activity of the two regions synchronized basically, and their strongest recorded earthquakes were both aroundM s 7.3. Seismic activity usually intensified before the occurrence of strong events. Aftershocks were frequent, but strong aftershocks usually occurred one to several years after the main shock. Two high tides of seismic activity occurred since the late 15th century. Around 1600, eight earthquakes each with magnitudes over 4.3 occurred in both of the two regions. The magnitude of the strongest shock in the south region is 6.7, that in the north region is 7.5. The second high tide occurred at the early 20th century. Among the 18 earthquakes occurred in the south region, one was of magnitude 7.3; whilst only two earthquakes with magnitudes 6.1 and 5.5 respectively occurred in the north region. Further, medium to strong earthquakes never occurred since 1942. Whether this is the “mitigation effect” of strong shocks, or a big earthquake is brewing in the north region is worth intensive study. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 505–515, 1991. This work is supported by Chinese Joint Seismological Science Foundation.  相似文献   

20.
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   

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