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1.
INTRODUCTIONManyhlstoric andrecent eaythquakes occurred along the Zhan9lakou－Penglal fanfaut zone situatedIn h。northern part of North China seismic regl()n(Fig．l),Including Sanhe－Pinggu MS．0 earthquakeonseptemberZ,1679 and Tangshan M7．8 eal’thquake on July28,1976．Afterthe Tangshanearthquake,a seismic quiescence along this zone lasted for 20 or more yeas without M 3 6．0eafthquake．Butonjanuary20,1998 theZhangbel M6．2 eafthquake occurred·Then the seismicactivity tends to …  相似文献   

2.
INTRODUCTIONTheDaqingshanpledmont扭nit Is an irllt,oltant active normal tsult In the active fault－depressionzone——Hetao ault－depression zone In the northern part of Ordos Block,North China．It lies in ENEdirection long the southern pledmont of Daqingshan Mountain,dips to south,and extends for 200 kmor。。The fault was formed In the Eocene and strongly activated In the Cenozolc．Its verticaldlspl。ement exceeds 2400 m since the Quaternary(Rese。h Group on Ordos Block,State…  相似文献   

3.
On the basis of the textual research on the historical earthquake data and the field investigation of Wudu earth- quake occurred in 186 B.C., we suggest that the earthquake parameters drawn from the present earthquake catalogs are not definite and amendments should be made. The heavily-damaged area of this earthquake should be located between Jugan township of Wudu County and Pingding township of Zhouqu County. Its epicenter should be in the vicinity of Lianghekou in Wudu County with a magnitude of about 7~7 41 and an intensity of about IX~X. The major axis direction of the heavily-damaged area should be in the WNW direction that is approximately consistent with the strike of the middle-east segment of Diebu-Bailongjiang active fault zone, and the origin time should match up to that of the latest paleoearthquake event [before (83±46) B.C.] obtained by the trench investigation. Certain seismic rupture evidences are still preserved on this fault segment. Therefore, we propose on the basis of comprehensive analysis that the causative structure of the M 7~7 4/1 Wudu earthquake in 186 B.C. should be in the middle-east segment of Diebu-Bailongjiang active fault zone.  相似文献   

4.
The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and analysed in this paper. The tempo-spatial scanning of LURR in the region of Iran during January 1, 2003 to March 31, 2006 has been conducted, with 1 year as a time-window, 1 month as a time-step, and the comparison of the LURR anomalous regions in 2004 with the actual earthquakes with M≥5.0 in the next year (2005) is also given, which shows that 11 earthquakes with M≥5.0 occurred in LURR anomalous regions while 12 earthquakes with M≥5.0 in LURR regions in 2005. Furthermore, the seismicity in this region is studied by investigating the evolvement of the anomalous LURR regions.  相似文献   

5.
<正>An earthquake with M7. 1 occurred in Yushu,Qinghai Province,China,at 07:49 a. m. on April 14,2010,according to the Chinese Seismic Station Network. The sequence is a fore-mainafter-shock type sequence. A foreshock with M4. 7 occurred 2 hours and 11 minutes before the main shock. There were 12 foreshocks and 2385 aftershocks until June 31,2010. In which,there are 21 aftershocks between M3. 0 and M3.  相似文献   

6.
INT正ODU**!0厂Nln以la Is located In the nol’th segmentdthe North－southselsnuc Belt,Whlchls thejuncturedthe Qinghai－Xizang(Dbet)block,Alxa block and Odos block．In that region,the tectonic activity。svery strong;。y strong earthquakes occu。d In history,such as the 1739 ingluo M。8．0 earthqu拙eandl920 Halyuan M。8．5 eafthquake,etc．; Merately strongeaFthquakes are still veryactlve atpresent,onlyln the Wuzhong－un斟m area,there have been7 e血hquakes tvlth M。＞5．0 to occ…  相似文献   

7.
Introduction XFJ reservoir has been about 40 years since its water loading in 1959 and has induced a great number of earthquakes. The largest one was the M = 6.1 earthquake occurred on March 19, 1962. Since then, a large amount of seismologists in our country have made many researches on the in-duced earthquake. In the paper, we have studied XFJ reservoir earthquakes and their relation with water cyclic fluctuation by using the mechanism solutions of small earthquakes occurred in these 40 y…  相似文献   

8.
库尔.  AK 吉姆.  AV 《内陆地震》2000,14(3):269-275
General Seismic Zoning Map of the USSR( GSZ- 78) ,included in the Building Code,inspite of relative improvement in comparison with previous ones( 1 937,1 95 7,1 96 8) ,is charac-terized by significantreduction of seismic hazard.In some regions strong earthquakes exceed-ing the predicted intensity occurred almost every year.Such cases in Kazakhstan are theearthquakes of Bakanasskoye( 1 979,M=1 4,I=6～ 7) and Zaysanskoye( 1 990 ,M=7.0 ,K=1 6 ,I=8) .Besides,there are territories that are …  相似文献   

9.
Introduction On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of ML=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. In total 87 events with ML3.0 were recorded by Beijing Telemetry Seismic Network (BTSN) before March of 1999. Before relocation the preliminary hypocenters determined by BTSN showed an epicentral distribution of 25 km long and 25 km wide without any predominate orientation. The epicentral a…  相似文献   

10.
ConsldeMle research has been po山med on the卜quency－删哪tude relation since仇tenbe恰Rlchterproposed the relationLog N＝a＋bM ()WhereM Is the nunlmumm昭nltude In the data sam卫ie for a celtaln region,N Is the cumulativeMquency ofevents In a celtaln time Interval ithm用刃ltude h锣rthan or equal to M,and a and bfilE COllstsfitS．Experimental researches on the G－R relation coMmed that the b decreases ith the de耶e ofbeteing6nelty and density Of the c。ohs In the。dlum(Mogi,1967)．The …  相似文献   

11.
In view of the correlation between tectonic activity and seismicity, the strong earthquake risk in the North-South Seismic Belt aroused wide concern after the 2014 Yutian Ms7. 3 earthquake. Using the seismic catalog of the China Earthquake Networks Center, the Benioff strain ratio in the North-South Seismic Belt is calculated in 30 days before and after the March 21, 2008 and February 12, 2014 Yutian Ms7. 3 earthquakes. Results show that in a year after the 2008 Yutian Ms7. 3 earthquake, M 〉 5. 0 earthquakes all occurred near the high strain ratio area or the junction between the low and high strain ratio areas, the activity of strong earthquakes obviously coincides with the high strain ratio area, which indicates that these areas have a higher stress level. The Yutian earthquakes promoted the release of small earthquakes in the high stress areas. This research is of certain indicating significance to the study of subsequent strong earthquakes of this region.  相似文献   

12.
Shallow seismic profiling in meizoseismal area of Xingtai earthquakes,phase division of Cenozoic movement of deep and shallow structures,analysis of characteristics of crustal and upper mantle structure,and comparative study on parameters of seismic sources indicate that the listric faults controlling the development of early Tertiary basin-range structure and eastward gently-dipping detachment below it in the Xingtai epicentral area are not related to the occurrence of Xingtai earthquakes.The Xingtai earthquake swarm is a product of threedimensional fracutre process in which the discontinuous “deep faults“,separated by NWtrending faults or by transverse barriers,successively tore,fractured,and propagated upward and ,hence,caused the stress between the adjacent deep faults to migrate and load under the action of latest tectonic stress field.The Xingtai seismogenic fault represents a “newly generated fault“ resulted from the upward tearing and propagation of the preexisting crustal“deep fault“.  相似文献   

13.
This paper introduces the geological structure background around the 2014 Yutian Ms7. 3 earthquake area, investigates and analyzes the regime of small earthquake activity and the characteristics of regional seismicity pattern in Xinjiang before the earthquake, and compares the characteristics of the regional seismic activity with the 2008 Yutian Ms7.3 earthquake. The results show： ① 2 ~ 3 years before the 2014 Yutian Ms7. 3 earthquake, Xinjiang was in a seismic active state with strong earthquake occurring successively, and before the 2008 Ms 7. 3 earthquake, Xinjiang was in the quiet state of moderate-small earthquakes with M3. 0 ~ 4. 0. ② Before this Yutian Ms7. 3 earthquake, the regional seismic activity showed a short-term anomaly feature, that is, seismicity of M ≥ 5. 0 earthquakes significantly increased on the Altun seismic zone and in the source area three years before the Ms7.3 earthquake, while a five year long quiescence of seismicity of M ≥4. 0 earthquakes appeared on the east of the source area in a range of about 440kin. Six months before this M7. 3 earthquake, there existed seismic gap of M3. 0 ~ 4. 0 earthquakes and near-conjugate seismic belt magnitude 3. 0 and 4. 0 in the source area. ③ The state of strong earthquake activity and the seismicity pattern of small earthquakes before this Yutian Ms7. 3 earthquake were significantly different to that before the 2008 Yutian Ms7. 3 earthquake, and this may be related to the different seismogenic environments of the two Ms7. 3 earthquakes.  相似文献   

14.
In this paper changes in focal mechanisms) parameters of wave spectra, and stress drops for the Ms=5.0 forcshock and Ms=6.0 mainshock in February 2001 in Yajiang County, Sichuan, and seismicity in cpiccntral region are studied. Comparison of focal mechanisms for the Yajiang earthquakes with distribution patterns of aftcrshocks, the nodal plane Ⅰ, striking in the direction of NEN, of the Yajiang M=5.0 event is chosen as the faulting plane, the nodal plane Ⅱ, striking in the direction of WNW, of the M=6.0 event as the faulting plane. The strikes of the two faulting planes are nearly perpendicular to each other. The level of stress drops in the cpicentral region before the occurrence of the M=6.0 earthquake increases, which is consistent with increase of seismicity in the epicentral region. The rate decay of the Yajiang earthquake sequence, changes in wave spectra for foreshocks and aftershocks,and focal mechanisms are complex.  相似文献   

15.
After completion of a study on predicting risky zones of earthquake of M≥8 for 1-3 years in the mainland of China,which was supported by Chinese Joint Seismological Science Foundation(D07018 and D08009),a further study was extended to that of greater magnitudes in the world.Based on the historical earthquake cases,we finished the research report,forecasting global earthquakes with magnitude more than 8.0 using the image analysis of seismicity.In this research report,we summarize 11 abnormal seismicity images for predicting earthquake of M≥8.0 around the world.In our research report,we predicted earthquakes of M≥8.0 from June 2009 to June 2014,the medium term predicting within 5 years period.Among these 5 predictive areas,three earthquakes occurred,which is Samoa M8.1 Earthquake on 29 September 2009,Talca M8.5 Earthquake on 27 January 2010,Chile,and Eastern Sendai M9.0 Earthquake on 11 March 2011,Japan respectively.Here we introduce the main items of the image analysis of seismicity and we predict three earthquakes and think that the image analysis of seismicity can be of help.  相似文献   

16.
The formation of strath and strath terrace is closely related to tectonic uplift in the drainage basin. Based on the investigation of straths at Yandantu and Changcaogou on the eastern segment of the northern margin fault of Altun, and in combination with the paleoclimatic data,the tectonic uplift since late Epipleistocene as revealed by stream terraces at the two places is discussed. At Yandantu, three levels of stream terraces( T1, T2 and T3 )have developed since 16ka BP, where T1, T3 and T2 are fill terraces and the buried major straths are exposed. The ages of three treads are dated to be about 16.1ka BP, 12 .Ska BP and 6.2ka BP, respectively. The three terraces reflect three tectonic uplift events, while the ages of the treads represent the occurrence time of these events. The stream is still beveling the bedrock and widening the channel at present, and the modern strath is being generated. The uplift rate is 4.8～4.5mm/a since 16.1 ka BP in this area. From 12.8ka B .P to 6.2ka BP, The uplift rate was 6.4mm/a.The uplift rate is 3. lmm/a since 6.2ka BP.At Changcaogou, four levels Of stream terraces(T1, T2, T3 and T1)have developed since 7ka BP. All of them are fill terraces. There are buried straths under the deposits. The buried major strath is exposed on T3 and T2 and the minor strath on T1‘and T1. The ages of treads of the three terraces (T3, T2 and T1’) are 7 ka BP, 3 ka BP and 2.5 ka BP, respectively. The four terraces reflect two uplift events induced by tectonic activities. One occurred in about 7 ka BP, and the other in 3ka BP. The uplift rate is 5.gmm/a since 7.0 ka BP at Changcaogou.From 7ka BP to 3ka BP, the uplift rate was 7.0mm/a, and since 3ka BP till now, the uplift rate is 4.7 mm/a.  相似文献   

17.
In the moment-ratio imaging algorithm, which is based on the theory of healing of a wound, the energy of each strong earthquake is distributed around the epicenter according to certain rules, and the features of the Moment-ratio value R are analyzed as the space and time change, so that the relationships between the moment-ration value R and strong earthquakes can be found. In the present paper, regions divided, hypocenter depths and events completed magnitude analyses were carried out in the Chinese catalogue. By applying the moment-ratio imaging algorithm in which the parameters are adjusted, the processes of anomaly evolution which correspond to the epicenter and the surrounding value R before earthquakes of M≥7.0 since 1966 in different areas of China were analyzed. It was found that the range area and imminent time of a coming earthquake could be confirmed quantita- tively by analyzing the abnormal temporal and spatial variation of the value R The results showed that the temporal and spatial variation of the value R could quantitatively reflect the temporal and spatial factors of a coming strong earthquake as well as the rule of medium rupture.  相似文献   

18.
Eastern Kunlun Active Fault Zone and Its Seismic Activity   总被引：8，自引：1，他引：8  
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19.
We examined the whole strong earthquake recurrence behaviors of two fault zones along the Kefallinia Transform, Ionian Sea, Greece, using seismological data and statistical methods. Our data include 29 events with %M%>5^5 for the period 1636～2003. We found different recurrence behaviors for the Kefallinia Fault Zone (clustering and time-predictable recurrence behaviors) and the Lefkada Fault Zone (near random and non-slip-predictable or non-time-predictable recurrence nature). The different modes may be attributed to: (a) segment interaction along-strike (Kefallinia) by static triggering and (b) the influence of fault systems to the north and east on the recurrence on Lefkada. Within the active periods, earthquake recurrence intervals are distributed in a more dispersed fashion, and can be fitted well by a Weibull distribution. In contrast, the distribution of the quiet periods is relatively less dispersed and difficult to describe by suitable probability functions.  相似文献   

20.
An earthquake with magnitude of 5.7 took place on Aug. 18, 2003 in the Nyingchi Region, Tibet. The macroseismic epicenter was located in the unpopniated high mountain area, 13 km south of Zhamo town, Bond County. The seismic intensity in the meizoseismal region was Ⅶ degree. The Ⅶ and Ⅵ areas were 2000 km^2 and 11000 km^2 , respectively. This seismic event is related to the movements of the Lhari fault trending in the NW direction and the ZhamoManiweng fault trending in the NE direction. As a result of this earthquakes, the buildings in the areas were badly damaged.  相似文献   

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