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1.
Introduction Increasing evidences show that the properties of candidate earthquake precursors seem to befocal mechanism dependent (Tsuruoka, et al, 1995; Reasenberg, 1999; Wan, et al, 2002). Test ofearthquake precursors without the classification of earthquakes could be misleading (Wu, 1999,Nature debates, http://helix.nature.com/debates/). In this paper we use the reported earthquakeprecursors for some earthquakes in China (ZHANG, 1988; 1990a, b; 1999; 2000; CHEN, 2002a, b;2003) to… 相似文献
2.
The time-frequency analysis and anomaly detection of wavelet transformation make the method irresistibly advantageous in non-stable
signal processing. In the paper, the two characteristics are analyzed and demonstrated with synthetic signal. By applying
wavelet transformation to deformation data processing, we find that about 4 months before strong earthquakes, several deformation
stations near the epicenter received at the same time the abnormal signal with the same frequency and the period from several
days to more than ten days. The GPS observation stations near the epicenter all received the abnormal signal whose period
is from 3 months to half a year. These abnormal signals are possibly earthquake precursors.
Foundation item: Joint Seismological Science Foundation of China (604021) and National Natural Science Foundation of China (40074024). 相似文献
3.
Retrospective forecasting test of a statistical physics model for earthquakes in Sichuan-Yunnan region 总被引：6，自引：0，他引：6
Pattern informatics (PI) model is one of the recently developed predictive models of earthquake phys- ics based on the statistical mechanics of complex systems. In this paper, retrospective forecast test of the PI model was conducted for the earthquakes in Sichuan-Yunnan region since 1988, exploring the possibility to apply this model to the estimation of time-dependent seismic hazard in continental China. Regional earthquake catalogue down to ML3.0 from 1970 to 2007 was used. The ‘target magnitude’ for the forecast test was MS5.5. Fifteen-year long ‘sliding time window’ was used in the PI calculation, with ‘anomaly training time window’ being 5 years and ‘forecast time window’ being 5 years, respectively. Receiver operating characteristic (ROC) test was conducted for the evaluation of the forecast result, showing that the PI forecast outperforms not only random guess but also the simple number counting approach based on the clustering hypothesis of earthquakes (the RI forecast). If the ‘forecast time window’ was shortened to 3 years and 1 year, respectively, the forecast capability of the PI model de- creased significantly, albeit outperformed random forecast. For the one year ‘forecast time window’, the PI result was almost comparable to the RI result, indicating that clustering properties play a more important role at this time scale. 相似文献
4.
IntroductionMany anomalies due to earthquake have been recorded in observation of earth-resistivity for30 years and over, which showed that there objectively existed the anomalies of each-resistivity.The crustal strUcture and medium conditions are quite complex, so the complexity of the temporal,spatial and intensive development of the anomalies is inevitable. Both of time and amplitUde ofanomalies among some stations near an epicenter are different (even among different observational directi… 相似文献
5.
新疆地下流体源兆、场兆、大震远兆特征的统计与分析 总被引：7，自引：0，他引：7
以20多年来新疆地区的18个地下流体监测点的资料为基础, 沿着“异常与震中”这一主线, 对新疆地区的16次5级地震、 4次 7级以上地震及1个6级强震群的前兆异常特征进行了定量的统计与分析。 结果表明, 源、 场、 远兆异常有如下特征: 异常空间展布不均, 源兆空间内异常监测点展布"密集"、 异常比例可达90%; 而场兆空间展布“稀疏”、 “分散”, 异常比例一般在45%～53%; 而远兆则是更加“稀疏”和“零星”, 异常比例统计为25%。 异常起始时间不同, 源兆异常时间以中期为主; 中强震场兆异常时间以中短期、 特别是短期为主; 强震场兆以中期异常为主; 而强震远兆则也以中期异常为主。 异常形态不同, 源兆中期异常及强震场兆中期异常一般是趋势性大幅度升高变化为主, 且以化学测项为多, 油气探井以井喷形式予以表现; 而中强震场兆异常, 一般表现为幅度明显的短期内的负异常、 脉冲突跳、 短期内的高值上升、 阶变及年变化规律被打破等; 强震远兆特征则基本上表现为少数测点、 测项的大幅度中期异常及个别测项的临震大幅度突跳现象, 油气探井则也以剧烈井喷形式予以表现。 相似文献
6.
The seismogenic fault and the dynamic mechanism of the Ning’er, Yunnan Province MS6.4 earthquake of June 3, 2007 are studied on the basis of the observation data of the surface fissures, sand blow and water eruption, land-slide and collapse associated with the earthquake, incorporating with the data of geologic structures, focal mecha-nism solutions and aftershock distribution for the earthquake area. The observation of the surface fissures reveals that the Banhai segment of the NW-trending Ning’er fault is dominated by right-lateral strike-slip, while the NNE-trending fault is dominated by left-lateral strike-slip. The seismo-geologic hazards are concentrated mainly within a 330°-extending zone of 13.5 km in length and 4 km in width. The major axis of the isoseismal is also oriented in 330° direction, and the major axis of the seismic intensity VIII area is 13.5 km long. The focal mechanism solutions indicate that the NW-trending nodal plane of the Ning’er MS6.4 earthquake is dominated by right-lateral slip, while the NE-trending nodal plane is dominated by left-lateral slip. The preferred distribution orientation of the aftershocks of MS≥2 is 330°, and the focal depths are within the range of 3~12 km, predominantly within 3~10 km. The distribution of the aftershocks is consistent with the distribution zone of the seismo-geologic hazards. All the above-mentioned data indicate that the Banhai segment of the Ning’er fault is the seismogenic fault of this earthquake. Moreover, the driving force of the Ning’er earthquake is discussed in the light of the active block theory. It is believed that the northward pushing of the Indian plate has caused the eastward slipping of the Qinghai-Tibetan Plateau, which has been transformed into the southeastern-southernward squeezing of the southwest Yunnan region. As a result, the NW-trending faults in the vicinity of the Ning’er area are dominated by right-lateral strike-slip, while the NE-trending faults are dominated by left-lateral strike-slip. This tectonic 相似文献
7.
IntroductionI.thasbeenpayingattentiontotheanomalousphenomenonbyseismologiststhattheearthquakeactivityoftenstrengthensinacertainspaceandduringacertaintimearoundthesourceareabeforeastrongearthquake.Mogi(1969)pointedoutthataringdistributiveareaofthestrengthenedearthquakeactivityoftenappearsaroundthesourcearea10to20yearsbeforegreatshock,whichcalledaringphenomenon(or"doughnut").Afterthat,otherscholarsreportedinsuccessionthatringdistributionofearthquakeactivityoccurredbeforeastrongertquakeorevenbefo… 相似文献
8.
The long-time practice of observational research on earthquake prediction has shown that the information on short-term and
imminent earthquake precursors can hardly be detected, but it is very important for practical and effective earthquake prediction.
The result of analysis and study in this paper has shown that the anomaly of quasi-static atmospheric electric field may be
a kind of reliable information on short-term and imminent earthquake precursors. On such a basis, the 20 years’ continuous
and reliable data of atmospheric electric field observed at the Baijiatuan seismic station are used to study the correlation
between the anomalies in seismic activity and relative quiet periods bear on the occurrence of near earthquakes within 200
km range around Beijing after the Tangshan earthquake. The observational results recently reported before hand in written
form and earthquakes that actually occurred in near field in corresponding time periods are compared and analyzed. The efficacy
of these written prediction opinions about near earthquakes in the recent 10 years is tested. From the test results, the brilliant
prospect that the anomaly of quasi-static atmospheric electric field may really become a reliable mark for making short-term
and imminent earthquake predictions is discussed. Besides, as a preliminary step, some judgment indexes for predicting earthquakes
by use of the observational data of atmospheric electric field before earthquakes are put forward. In the last part, it is
pointed out that it would be possible to obtain more believable judgment indexes for determining the three elements of near
earthquakes before greater earthquakes (M
S≥5) only if a relatively reasonable station network (2–4 stations every 10 000 km2) is deployed and further investigation is made.
Contribution No. 97A0040, Institute of Geophysics, State Seismological Bureau, China.
This subject is sponsored by Program No. 95-04-05-01-04, State Seismological Bureau, China. 相似文献
9.
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
10.
Response spectrum of seismic design code for zones lack of near-fault strong earth- quake records 总被引：1，自引：0，他引：1
It was shown from the study on the recently near-fault earthquake ground motions that the near-fault effects were seldom considered in the existing Chinese seismic code. Referring to the UBC97 design concept for near-fault factors, based on the collected world-widely free-site records of near-fault earthquakes ground motions classified by earthquake magnitude and site condition, the attenuation relationship expressions of the acceleration spectrum demand at the key points within the long period and moderate period were established in term of the earthquake magnitude and the site condition. Furthermore, the near-fault factors’ expressions about the earthquake magnitude and the fault distance were deduced for the area lack of near-fault strong earthquake records. Based on the current Chinese Building Seismic Design Code, the near-fault effect factors and the modified design spectral curves, which were valuable for the seismic design, were proposed to analyze the seismic response of structures. 相似文献
11.
Introduction Beijing and the adjacent regions is a significant seismically active area and many geoscien- tists have studied to different extents the non-elastic attenuation and source parameters in the area. GAO et al (1986) and ZHUO et al (1990) studied the coda Q in the Beijing region by the method of dominant frequency and mechanical frequency division with the simulated data. With the con- tinuous construction of digital seismic station network, the digital data are more favorably used… 相似文献
12.
The strong earthquakes in western Yunnan area, mainly occur along great interplate strike-slip faults and have a dominant
depth-layer about 10–20 km; the seismic rupture is characterized by strike-slip rupture. Considering the Yunnan lithospheric
structure and dynamic background, we think that earthquakes occurring at this area might have such a kind of nucleation process:
because of the multi-layers and heterogeneities of lithospheric structure, a zone of concentrated shear strain or of slip
might be formed at the moderate or deep portions of lithosphere, and spread upward along faulting boundary, toward the earth’s
surface under the background field of tectonic movement of lithospheric plates. The slip front will encounter the maximum
shear resistance zone on the fault surface in this process, be barried and blocked, and form a seismic gap. With the increase
of tectonic load, this slip zone will continuously spread forward, traverse and lead to instable crack of the whole blocked
zone, and cause a great earthquake. We have derived an approximate integral equation describing this seismic process; the
numerical results show that the model has an instable nonlinear accelerating evolution period which might have important significance
for the generation of earthquake precursors.
This paper is supported by the Eight Five-Year Target of the State Seismological Bureau, China. 相似文献
13.
On the basis of the reality of recent tectonic movement and discarding such a viewpoint that the isostatic adjust-ment only results from excessive or insufficient compensation,we have discussed the tectonic stress causing ine-auality and regarded the isostatic anomaly as a load on the earth‘s interior,thus the earth‘s inner stress can be cal-culated.The research results show that in the East China Sea and its eastern marginal seas the change of the verti-cal stress derived from the isostatic gravity anomaly is more marked than that of the horizontal stress.Along the Ryukyu trench there is an enhancement of vertical stress by 5MPa,which evidently reflects the effect of plate subduction.On contrary,along the island are to the northwest of the trench the vertical stress weakens by about5MPa.The horizontal stresses in eastern and western parts are obviously different,the east westward stress on the oceanic crust σx is negative(while the pressure is positive)but on the continental crust in positive.These facts indicate the effect of compression between plates. 相似文献
14.
Ran Hong-liu 《地震学报(英文版)》2004,17(6):671-677
In recent years, some researchers have studied the paleoearthquake along the Haiyuan fault and revealed a lot of paleoearthquake
events. All available information allows more reliable analysis of earthquake recurrence interval and earthquake rupture patterns
along the Haiyuan fault. Based on this paleoseismological information, the recurrence probability and magnitude distribution
for M≥6.7 earthquakes in future 100 years along the Haiyuan fault can be obtained through weighted computation by using Poisson
and Brownian passage time models and considering different rupture patterns. The result shows that the recurrence probability
of M
S≥6.7 earthquakes is about 0.035 in future 100 years along the Haiyuan fault.
Foundation item: Joint Seismological Science Foundation of China (103034) and Major Research “Research on Assessment of Seismic Safety” from
China Earthquake Administration during the tenth Five-year Plan. 相似文献
15.
Fracture characteristics of the 1997 Jiashi, Xinjiang, China, earthquake swarm inferred from source spectra 总被引：2，自引：0，他引：2
SHI-YONG ZHOU 《地震学报(英文版)》2000,13(2):125-135
Broadband P and S waves source spectra of 12 MS5.0 earthquakes of the 1997 Jiashi, Xinjiang, China, earthquake swarm recorded at 13 GDSN stations have been analyzed. Rupture size and static stress drop of these earthquakes have been estimated through measuring the corner frequency of the source spectra. Direction of rupture propagation of the earthquake faulting has also been inferred from the azimuthal variation of the corner frequency. The main results are as follows: ①The rupture size of MS6.0 strong earthquakes is in the range of 10～20 km, while that of MS=5.0～5.5 earthquakes is 6～10 km.② The static stress drop of the swarm earthquakes is rather low, being of the order of 0.1 MPa. This implies that the deformation release rate in the source region may be low. ③ Stress drop of the earthquakes appears to be proportional to their seismic moment, and also to be dependent on their focal mechanism. The stress drop of normal faulting earthquakes is usually lower than that of strike-slip type earthquakes. ④ For each MS6.0 earthquake there exists an apparent azimuthal variation of the corner frequencies. Azimuthally variation pattern of corner frequencies of different earthquakes shows that the source rupture pattern of the Jiashi earthquake swarm is complex and no uniform rupture expanding direction exists. 相似文献
16.
经统计与研究,多数地震是不引发海啸的,故地震与海啸不存在直接的因果关系。这是因为引发地震海啸(特别是大的地震海啸)的直接原因,主要是海底地震所造成的次生的巨大体积的海底滑坡和崩塌,而不是海底地震时海底地面的同震错断与变形。因此,若未来震中附近存在不稳定海底滑坡和崩塌体,只要发生地震,不论震级大小与震源深浅,也不论震源类型(即倾滑或走滑)都可引起海底滑坡和崩塌,进而引发海啸。若未来震中附近不存在不稳定海底滑坡和崩塌体,再大震级的地震,即使是倾滑型地震也不能引发海啸 相似文献
17.
马钦忠 《地震学报(英文版)》2008,21(6):618-628
On July 4,2006,a MS5.1 earthquake occurred in Wen’an county of Hebei Province of which the epicenter is near the Beijing city.The six geoelectric field monitoring stations have been in operation for several years around the Beijing area to examine the relationship between electric field changes and earthquake.This paper firstly explains the principle of the eliminating noise method by using multi-dipole observation system of the geoelectric field.Then the data observed at the stations are studied and a lot of abnormal signals preceding the Wen’an earthquake are selected,of which five abnormal signals of the geoelectric field are finally recognized as the precursory signals.The result shows that 1 there probably exists the precursory signals of the geoelectric field preceding the Wen’an earthquake;2 there are sensitive sites in the spatial distribution of the abnormal variation of the geoelectric field before the quack;3 the anomalous signals do not appear synchronously,and their durations are not same at dif-ferent stations;4 the amplitudes of the abnormal signals recorded at Baodi station are small,but large at Changli station,while the latter is farther from the epicentral area than the former. 相似文献
18.
川滇地区走滑型地震烈度衰减特征研究 总被引：3，自引：0，他引：3
为分析走滑型地震的烈度衰减特征, 我们搜集并整理1900年以来川滇地区的145个5级以上震例和其中70个5级以上、 破裂方式以走滑型为主的典型震例, 利用联合椭圆衰减模型, 建立该区域此类型地震烈度衰减关系。 对比已有研究成果, 结果表明, 川滇地区破裂方式以走滑型为主的地震烈度衰减速度慢于西南地区, 可能与该地区地震破裂方式、 动力学过程等有关, 但与川滇地区和中国西部的衰减规律相比没有明显差异。 本文给出的烈度衰减关系在该区域此类地震的灾害快速评估和地震应急中具有一定参考价值, 其他区域的适用性需进一步分析。 相似文献
19.
Wu Fu-chun Song Li-sheng Zhu Xing-guo Wang Feng Jing Bei-ke Dong Xing-hong Fang Wei Zuo Yong-qing 《地震学报(英文版)》2001,14(4):434-439
Based on the analysis of the induced earthquakes in China and abroad, we get some ideas about earthquakes induced by pumping
water out of a well or injecting water into a well. The induced earthquakes usually occur near the well, and they are generally
small earthquakes. The earthquake sources are shallow, and they belong to the main shock-after shock type of earthquake or
the swarm-type of earthquake. The magnitude and the quantity of the induced earthquakes obviously depend on the pressure and
the quantity of water pumped or injected. These earthquakes happen as soon as pumping or injecting occurrence, or after ten
or twenty days, they may occur at the time of injecting mud or injecting high pressure water when a well is being drilled,
or at the time when the ground water is being normally exploited. A large quantity of hot water has been exploited since 1990
in Xi’an, and the quantity of water exploited has been increasing year by year, as a result the groundwater level has been
dropping with the water pumped out and the water level is high in summer and low in winter. The earthquakes in Xi’an region
belong to the solitary-type and they spread outside Xi’an city where the wells are concentrated but no earthquake happens.
The seismic frequency and the energy released have no relation with the quantity of water exploitation or the water level
in the well. It is considered that geothermal exploitation does not induce earthquakes in and around Xi’an because of its
specially geological condition.
Foundation item: Project sponsored by the Landslide Office of Shaanxi Province and Society of Disaster Reduction of Shaanxi Province. 相似文献
20.
Estimation of the 2001 Kunlun earthquake fault slip from GPS coseismic data using Hori's inverse method 
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下载免费PDF全文 The Horios inverse method based on spectral decomposition was applied to estimate coseismic slip distribution on the rupture plane of the 14 November 2001 <i<M</i<<sub<S</sub<8.1 Kunlun earthquake based on GPS survey results. The inversion result shows that the six sliding models can be constrained by the coseismic GPS data. The established slips mainly concentrated along the eastern segment of the fault rupture, and the maximum magnitude is about 7 m. Slip on the eastern segment of the fault rupture represents as purely left-lateral strike-slip. Slip on the western segment of the seismic rupture represents as mainly dip-slip with the maximum dip-slip about 1 m. Total predicted scalar seismic moment is 5.196?×10<sup<20</sup<N·m. Our results constrained by geodetic data are consistent with seismological results. 相似文献