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1.
Zhang Xiaodong 《中国地震研究》2004,18(2):171-177
The active and quiet phenomenon of moderate strong earthquakes one year before the earthquakes with M S≥7.0, the spatial distribution characteristics of the solid tide modulating and triggering earthquakes and the strong earthquake mechanisms on the Chinese continent have been studied. The secondary arcuate tectonic zone composed of the west Kunlun-Anyêmaqên faults is believed to be a very important boundary to characterize strong earthquake activity of M S≥7.0 on the Chinese continent, that is, a boundary between the seismically active region and the quiet region of moderately strong earthquakes one year before earthquakes with M S≥7.0, and a boundary of the spatial distributions between the solid tide modulating strong earthquakes (M S≥7.0) and the non-modulating ones. It might be related with the characteristics of spatial distribution of focal mechanism solutions of strong earthquakes on the Chinese Continent. 相似文献
2.
The characteristics of seismic activity in different time-spatial domain before the Mw9.0 earthquake were studied. The results are as follows ： ① The activity of the deep earthquakes in the north boundary zone of the Australian plate had been evidently strengthened since 1994, showing an increased frequency, magnitude and depth, especially in regards to the heterogeneous distribution of the earthquake depth （namely between 500km and 689km）. Meanwhile the shallow earthquakes of M ≥ 7.0 in the Sumatra island and its vicinity had been obviously strengthened too, and formed a strengthening area with a length of about 1000 km and width 300 km. ②The time distribution of global strong earthquakes with M≥ 7.0 shows that the character of anomalous seismic quiescence-activity one year before the Mw9.0 earthquake and during its active period, the strong earthquakes formed a seismic belt striking in NWW direction. At the same time, there is a seismic gap formed by earthquakes of M ≥ 5.0 in the epicenter and its neighboring region. ③ Two deep earthquakes of M ≥ 7.0 occurred in the west and in the east of the north boundary zone of the Australian plate half year ago. It is notable that one of them occurred in the Sumatra island where no deep earthquake with M ③ 6.0 has occurred in the past thirty years. ④The space distribution of moderate shocks occurring three days ago exhibited a NWW-strike seismic belt along the north boundary zone of the Australian plate. ⑤The activity of volcanoes distributed in the north boundary zone of the Australian plate had been strengthened in the past 4 years, especially several months before the occurrence of the Mw9.0 earthquake. 相似文献
3.
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
4.
Based on the hypothesis of the active tectonic blocks on the Chinese continent and its adjacent regions (both the method of the DDA on a spherical surface and the GPS survey results observed from 1991 to 2001 are used), the movements and deformations of each active tectonicblock are calculated. The calculation results show that although the movements and deformations of active tectonic-blocks in the eastern region and in the western region of China are different, active tectonic blocks in the same active tectonic block region are coherent.Then, the relative velocities of the active tectonic-blocks‘ boundary zones are calculated, and the relationship between current crustal motion and strong seismic activities is discussed. Earthquakes (Ms≥7.0) on the Chinese continent since 1988 all occurred on boundary zones of active tectonic blocks with high slipping speed. 相似文献
5.
LiGang LiuJie YuSurong QinDongling 《中国地震研究》2004,18(1):97-104
In 2003, a total of 20 strong earthquakes with Ms7.0 occurred in the world as determined by the Chinese Seismic Station Network (Table 1). The strongest one was the Hokkaido earthquake with Ms=8.0 on September 26 (Fig. 1). When compared with 2002, the frequency and energy release of earthquakes in 2003 increased obviously. The characteristics of activity of global earthquakes with Ms7.0 will be discussed here. 相似文献
6.
1 SURVEY OF GLOBAL SEISMICITY IN 2006
A total of 15 strong earthquakes with Ms ≥ 7.0 occurred in the world according to the Chinese Seismic Station Network in 2006 （Table 1 ）. The strongest earthquakes were the Kamchatka earthquake with Ms8.0 on March 29 and the Kuril Islands earthquake with Ms8.0 on November 15 （Fig. 1）. The frequency was slightly lower, and the energy release of earthquakes reduced in 2006 compared with the seismicity in 2005. The seismicity last year had the following characteristics： 相似文献
7.
After the Ms6.6 earthquake occurred in the border region between Min and Zhang counties of Gansu Province on July 22, 2013, we preliminarily estimated the earthquake sequence to be a main shock-aftershock type based on the history of moderate-strong earthquake sequences in this area. As time went on, there were more aftershock events. These could be used for further analysis, and then for further decision on the earthquake sequence type. Finally, we determined the Ms6.6 earthquake sequence that occurred in the border region between Min and Zhang counties, Gansu Province as having been a main shock-aftershock type, with the largest Ms5.6 aftershock having occurred on the same day as the main Ms6.6 shock, from a comprehensive analysis of the historical characteristics of moderatety strong earthquakes of the earthquake zone, and the space-time evolution characteristics and parameters of the earthquake sequence. These provided a correct basis for anti- earthquake relief work and played an important role in mitigating the earthquake disaster and stabilizing the disturbed soci- ety after the earthquake in the earthquake zone and its neighboring areas. Reviewing the forecasting process and the re- sults, we found that we had successfully predicted the Ms6.6 earthquake that occurred in the border region between Min and Zhang counties on July 22, 2013 several years before it occurred. The magnitude and location of the earthquake had been predicted accurately, and the accuracy of the prediction was much higher than any other example in Chinese earth- quake prediction history. Forecasting on a monthly scale, we had indicated at the monthly meeting on earthquake prediction at the end of February, 2013 that there would be a risk of a moderately strong earthquake in Gansu Province from the change in moderately strong earthquake activity on the Chinese mainland. Even for short and impending earthquake prediction from several days to several dozens of days, we had proposed the likelihood of a moderate-strong earthquake happening in Gansu Province and the adjacent areas from the results of previous studies and the cases of earthquakes with MI ≥ 4.0 from the time before the Ms6.6 earthquake occurred. In a meeting about earthquake prediction held several days before the occurrence of the Ms6.6 event, we made the prediction that there would be an earthquake of M≥ 5.0 happening somewhere in Gansu Province and the surrounding area within dozens of days. The fact we had successfully predicted the Ms6.6 earth-quake on a several-year scale, as well as over a short time period to some extent, reinforces our belief that earthquakes can be forecast. Even with our present level of understanding, we can still capture some information on the gestation and occurrence of earthquakes before the arrival of a disaster. However, in order to achieve the goal of earthquake prediction in China, earthquake scientists still need to make arduous efforts. As long as earthquake scientists use the correct approach, and government supplies the necessary manpower and material resources to predict earthquakes, we believe that there will be a hope to achieve the aim of earthquake prediction with a relief effect. It is promising that we have achieved at least one or two earthquake forecasts. 相似文献
8.
TianShan GuanHuaping WuGuoyou LiuYunxiu 《中国地震研究》2004,18(3):271-280
The earth resistivity and geomagnetic observation data of the Z component from many stations in near-epicentral areas of strong earthquakes are combined and calculated by using a spatial linearity method and a new characteristic value, the spatial linearity a, describing the precursory field in near-epicentral area of strong earthquake, is obtained. The analysis and calculation results of geoelectric and geomagnetic observation data prior to 8 earthquakes with M≥5.5 occurring in the North China region show that a value near the epicentral area tendsto decrease significantly half a year before strong earthquakes. 相似文献
9.
A total of 16 strong earthquakes with Ms≥7.0 occurred in the world in 2002 according to the determination of the Chinese Seismic Station Network (Table 1 ). The two strongest earthquakes were Sumatra earthquake (Ms7.8, November 2) and Alaska earthquake ( Ms 7.8 November 4) . Fig. 1 is the distribution of strong earthquakes that occurred in 2002. The global seismicity pattern in 2002 was similar to the ones since 1999. The frequency and strength apparently decreased in 2002 compared with the seismicity in 2001. 相似文献
10.
By applying the GL-value, a parameter describing the heterogeneities in temporal and spatial distribution of moderate and small earthquakes prior to strong earthquakes, the following problems have been studied in the present paper: a systematic investigations have been made on the features of spatial distribution and temporal variation of the high value anomalies ( GL ≥1.0) prior to 28 moderately strong earthquakes with Ms ≥5.0 in the North China region; a systematic study has been made on the reasonability of the lower limit of magnitude, the time window and the space window for calculations at various seismicity levels in this region; the parameters taken in the calculation have been optimized and modified; the anomalous variations of GL-value prior to various moderately strong earthquakes in North China region have been investigated and followed, using the total time-space scanning method. The results of the study have shown that for 82 % of the moderately strong earthquakes in the North China region, obvious anomalous region with high GL-values appears near the future epicenter about 1 ～ 3.5 years before the earthquakes. The earthquakes usually occur in the marginal area of the anomalous zone or near it. Temporal variations of the GL-values in the anomalous zone show that the duration of anomalous ranges between 3 ～ 25 months with a predominant interval of 5 ～ 19 months, into which about 70% the total anomalies fall. The predominant interval of earthquake occurrences is 0 ～ 14 months after ending of the anomaly, into which about 83 % of the total anomalies fall. Based on these results the GL-value method is considered to be a rather effective prediction method for moderately strong earthquakes in the North China region. 相似文献
11.
《地震科学（英文版）》2010,(4)
The tempo-spatial variation of seismic activity before great Chile MW8.8 earthquake on February 27,2010 is studied.Some results are as follows:1 Two types of seismic gaps appeared before the Chile MW8.8 shock.One is background gap of MW≥8.0 earthquakes with 360 km length since 1900,the other is seismogenic gap formed by M≥5.5 earthquakes with 780 km length five years before the Chile earthquake;2 There was only one MW7.1 earthquake in the middle and southern part of Chile from 1986 to 2010.The obvious quiescence of MW≥7.0 earthquake is the long-term background anomaly for the Chile earthquake;3 The quiescence of M≥6.5 earthquakes appeared in South American block and its vicinity during the period from 2007 to 2009,and the quietude state has been disappeared three months before the Chile MW8.8 earthquake;4 The deep and intermediate-depth earthquake activity has been noticeablely strengthened in the subduction zone of South American block since 1993;5 The great Chile earthquake shows that global seismicity is still in the active period of MW≥8.5 earthquakes since 2004.Based on the characteristics of the former two active periods,several great earthquakes with MW≥8.5 would take place in a few years.In addition,the circum-Pacific seismic belt would be the main region for MW≥8.0 earthquakes. 相似文献
12.
《地震科学（英文版）》2010,(4)
The September 21,1999,Jiji(Chi-Chi) MW7.6 earthquake is the strongest event occurred since 1900 in Taiwan of China.It is located in the middle segment of the western seismic zone of Taiwan.Based on several versions of China earthquake catalogue this study found that a seismic gap of M≥5 earthquakes appeared,in and around the epicenter region,24 years before and lasted up to the mainshock occurrence.This study also noticed that there existed a lager seismically quiet region of M≥4 earthquakes,which lasted for about 2.5 years before the mainshock occurrence.The spatial variation pattern of regional seismicity before the mainshock seems to match with its coseismic source rupture process.The mentioned seismicity gap and seismic quiescence might be an indication of the preparation process of the Jiji strong earthquake. 相似文献
13.
According to the earthquake focal mechanism solutions of 55 moderately strong earthquakes onthe northeastern side of Pamirs,the spatial and temporal distribution of earthquakes ith M_s≥6.0 since this century and the characteristics of hypocenter depth distribution of earthquakeswith M_s≥3.0 since 1980 in this region,the article discusses the relation between regional tee-tonic stress fields and strong earthquake activity.The result shows that the hypocenter disloca-tion is mostly strike-dip,partly dip-slip,and the direction of the principal compressional stressis nearly NS.The distributive characteristics of strong shock activity is obvious,with the gen-eral trend that the west is strong and the east is weak,which can be divided into three imephases,and each with relative principal active region The depth near Pamirs aren reaches200km,shallower obviously when externding to NE,less than or equal to 40km near the Kalpinblock,and the article discusses the result. 相似文献
14.
on Septmeber 23,1999,an earthquake swarm occured in Fuzhou,Because the swarm occurred in the region where earthquaks occurred scarcely before and very close to the center of the city as well as shortly after the Jiji earthquake with Ms7.6 in Taiwan,September 21,1999,has aroused interest broadly.In this paper,we analyzed the characteristics of spatial and temporal distribution of the earthquake swarm and validated magnitude-number constituent of the swarm is special.In present theory,the earthquake swarm means that a small scale macro original rupture has formed in the layer of the crust in Fuzhou region where moderately strong earthquake risk exists. 相似文献
15.
We have studied the seismicity features of M_S≥5.0 earthquakes two years before strong earthquakes with M_S≥7.0 occurred in the central-northern Qinghai-Xizang (Tibet) block since 1920. The results have showed that there is an obvious gap or quiescence of M_S5.0～6.9 earthquakes near epicenters. We have also studied statistical seismicity parameters of M_S5.0～6.9 earthquakes in the same region since 1950. The results have showed that earthquakes with M_S≥7.0 occurred when earthquake frequency is relatively high and earthquake time, space accumulation degrees are rising. And the prediction effect R value scores are between 0.4～0.7. We have concluded that, before earthquakes with M_S≥7.0 in the central-northern Qinghai-Xizang (Tibet) block, M_S5.0～6.0 earthquake activity in the whole area increased and accumulated in time and space, but earthquakes with M_S≥7.0 occurred where M_S5.0～6.0 earthquake activity was relatively quiet. 相似文献
16.
26 earthquakes with MS ≥5. 0 have been recorded in the northeast margin of the Qinghai- Xizang (Tibet) block since 1980,22 of which were relatively independent of other moderate- strong earthquakes. Research on the increase of small earthquake activity before the 22 moderate-strong earthquakes has indicated that small earthquake activity was enhanced before 17 of the moderate-strong earthquakes. Though the increased seismicity is a common phenomenon in the northeast margin of the Qinghai-Xizang ( Tibet ) block,we have difficulty in predicting the moderate-strong earthquakes by this phenomenon. In order to predict the moderate-strong earthquakes through the increased seismicity of small earthquakes,this paper attempts to propose a new method, which calculates small earthquake frequency through the change of distribution pattern of small earthquakes, based on the characteristics of small earthquake activity in the northeastern Qinghai-Xizang (Tibet) block,and then make primary applications. The result shows that we are able to obtain obvious anomalies in the frequency of small earthquakes before moderate strong earthquakes through the new method,with little spatial range effect on the amplitude of this small earthquake frequency anomaly. We can obtain mid to short-term anomaly indices for moderate-strong earthquakes in the northeast margin of the Qinghai-Xizang (Tibet) block. 相似文献
17.
《中国地震研究》1994,(2)
In this paper,the time-space features of Ms≥6.0 strong earthquakes that have occurred on the Chinese mainland since the beginning of this century were analyzed; the effect of Ms≥7.0 large shocks in mitigating Ms≥6.0 strong earthquakes subsequent to them vas studied both temporally and spatially; and the accumulative probabilities for the occurrence of Ms≥6.0 strong earthquakes subsequent to Ms≥7.0 large shocks were calculated.The results seem to imply that the effect of Ms≥7.0 large shocks in mitigating subsequent strong events is relatively obvious within certain time-space ranges.This is because the strain energy accumulated over a long time in the region around the source has been mostly released through the fracture produced by the large shock,the possibility for another large fracture to occur again in the same region within a certain period of time has been greatly reduced and therefore the probability for subsequent strong earthquakes to occur in that region is very low.These results can be 相似文献
18.
Wang Qiong 《中国地震研究》2007,21(3):255-268
The Bachu-Jiashi earthquake of Ms6.8 occurred on February 24, 2003, about 20km from the southeast of the 1997 - 1998 Jiashi seismic region in Xinjiang, and its aftershocks are rich and strong. Did the 1997 - 1998 Jiashi strong earthquake swarm trigger the Bachu-Jiashi Ms6.8 earthquake？ The Atushi earthquake of Ms6.7 occurred in 1996, and the 1997 - 1998 Jiashi strong earthquake swarm occurred about 70km from the Atushi earthquake 10 months later. Did the Atushi earthquake of Ms6.7 encourage the 1997 - 1998 Jiashi strong earthquake swarm？ There were 9 earthquakes with Ms6.0 from 1996 to 1997 in the Jiashi seismic region, how did they act on each other？ To answer the above questions, the article studies the triggering effect of the activity process of the whole Jiashi earthquake swarm from the 1996 Atushi earthquake of Ms6.7, the 1997 - 1998 Jiashi strong swarm to the 2003 Bachu-Jiashi earthquake of Ms6.8, and analyzes the seismicity characteristics around the Jiashi region. The results show that the 1996 Atushi earthquake of Ms6.7 encouraged the 1997 - 1998 Jiashi strong swarm to some extent, the accumulative Coulomb stress change from the previous M6.0 earthquakes of the Jiashi strong swarm had certain triggering effects on the following M6.0 events, and the Coulomb stress change converted from the Jiashi strong swarm strongly encouraged the 2003 Bachu-Jiashi earthquake with Ms6.8. 相似文献
19.
The temporal and spatial distribution characteristics of earthquakes in the Ordos block are studied by using historical earthquake data,instrument data of the regional seismic network around the Ordos block and the historical felt earthquake data,and the relationship between seismicity in the Ordos block and seismicity around the Ordos block is discussed. The result shows that the Ordos block is a typical moderate-strong earthquake active region where many M_S≥5.0 destructive earthquakes have occurred. The temporal and spatial distribution of earthquakes in the Ordos block is asymmetrical. The temporal distribution of earthquakes shows a periodic characteristic and the activity of earthquakes in the southeastern Ordos block is higher than in the northwest Ordos block. The M_S≥5.0 moderate size earthquakes in the Ordos block are controlled by the M_S≥6.0 earthquake around the Ordos block. 相似文献
20.
In this paper, we focused on earthquakes with Ms ≥ 7.0 in the Chinese mainland from 1900 to 2012, calculated the lunisolar tidal Coulomb failure stress on the seismic fault plane and got the tidal phase through Schuster＇s test, then quantitatively analyzed the correlation between strong earthquakes in the Chinese mainland and tidal Coulomb failure stress. Research shows that among 57 strong earthquakes with focal mechanism solutions, over 71.9% took place within the tidal loading phase, with the p-value of 3.83%, indicating that strong earthquakes with Ms ≥ 7. 0 in Chinese mainland have a certain correlation with lunisolar tidal Coulomb failure stress. In the active period, the p-value is 4. 56%, 75.5% of earthquakes occurred in the tidal loading phase zone, and 50% of earthquakes occurred in the quiescence period, indicating that strong earthquakes in the active period were obviously triggered with the tidal Coulomb failure stress loading. 相似文献