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1.
Statistical properties of reported earthquake precursors show apparent focal mechanism dependence. Intensity of anomaly is
described by the ‘anomaly ratio’ as defined by the number of stations/items reporting anomalies before the target earthquake
over the number of stations/items in operation around the target earthquake. Variation of the ‘anomaly ratio’ with the magnitude
of the target earthquake was studied for dip-slip earthquakes all over China, strike-slip earthquakes in eastern China, and
strike-slip earthquakes in western China, respectively. It is observed that for strike-slip earthquakes, the ‘anomaly ratio’
increases linearly with the magnitude of the target earthquake, while earthquakes in eastern China and western China have
different slopes. For dip-slip earthquakes, however, the ‘anomaly ratio’ has no statistically significant change with the
magnitude of the target earthquake. Limited data imply that the ‘anomaly ratio’ seems proportional to the apparent stress
of the target earthquake. The result might be heuristic for the analysis of candidate earthquake precursors.
Foundation item: National Natural Science Foundation of China (40274013) and MOST Project (2001BA601B02).
Contribution No.04FE1020, Institute of Geophysics, China Earthquake Administration. 相似文献
2.
Cities’ ability reducing earthquake disasters is a complex system involving numerous factors, moreover the research on evaluating
cities’ ability reducing earthquake disasters relates to multi-subject, such as earthquake science, social science, economical
science and so on. In this paper, firstly, the conception of cities’ ability reducing earthquake disasters is presented, and
the ability could be evaluated with three basic elements — the possible seismic casualty and economic loss during the future
earthquakes that are likely to occur in the city and its surroundings and time required for recovery after earthquake; based
upon these three basic elements, a framework, which consists of six main components, for evaluating city’s ability reducing
earthquake disasters is proposed; then the statistical relations between the index system and the ratio of seismic casualty,
the ratio of economic loss and recovery time are gained utilizing the cities’ prediction results of earthquake disasters which
were made during the ninth five-year plan; at last, the method defining the comprehensive index of cities’ ability reducing
earthquake disasters is presented. Thus the relatively comprehensive theory frame is set up. The frame can evaluate cities’
ability reducing earthquake disasters absolutely and quantitatively and consequently instruct the decision-making on reducing
cities’ earthquake disasters loss.
Foundation item: State Important Research Project of China (95130603). 相似文献
3.
The seismic future of cities 总被引：1，自引：0，他引：1
Roger Bilham 《Bulletin of Earthquake Engineering》2009,7(4):839-887
The final projected doubling in Earth’s population in the next half century, requires an additional 1 billion housing units,
more dwellings constructed in a single generation than at any time in Earth’s history. Earth’s tenfold increase in population
has occurred during a time that is short compared to the return time of damaging earthquakes. In the next century, therefore,
earthquakes that had little impact on villages and towns, will be shaking urban agglomerations housing upwards of 12 million
people. An epicentral hit on a megacity has the potential to cause 1 million fatalities. The incorporation of earthquake resistant
structures in the current global building boom, despite successes in the developed nations, has been neglected in the developing
nations where historically earthquake damage has been high. The reasons for this neglect are attributed to indifference, ignorance
and corrupt practices, not due to an absence of engineering competence. Never has a generation of earthquake engineers been
faced with such a grave responsibility to exercise their skills, both political and technical, as now.
The eye is bewildered by “a city become an heap”. Robert Mallet (1862).相似文献
4.
Introduction The January 10, 1998 Zhangbei-Shangyi, Hebei Province, earthquake has been the third large event of magnitude 6.0 and greater since the 1976 great Tangshan earthquake of magnitude 7.8 in the northern China (33皛42癗, 110皛124癊). Before this event, there were only two events of magnitude 6.0 and greater occurred in or around the Tangshan area since 1976: the M=6.9 Ninghe, Tianjin, earthquake of November 15, 1976 and the M=6.2 Hangu, Tianjin, earthquake of May 12, 1977. The … 相似文献
5.
ZHANG Heng＇s Seismometer and Longxi earthquake in AD 134 总被引：1，自引：0，他引：1
6.
Introduction At present, China Earthquake Administration (CEA), National Nature Science Foundation(NNSF) of China, Geological Survey (USGS), National Science Foundation (NSF) of UnitedStates and Incorporated Research Institutions for Seismology (IRIS) all support Sino-Americatechnical cooperation project— China Digital Seismograph Network (CDSN). Institute of Geo-physics, China Earthquake Administration (IGCEA) and Albuquerque Seismological Laboratory,Geological S… 相似文献
7.
In this study near field strong ground motion generation of Mw 6.9 scenario events on Gemlik Bay was presented at broadband
frequency (0.5–10 Hz) ground motion at 9 stations. In the first stage of the study, focal mechanism of a small earthquake,
which was used as the Empirical Green’s Function (EGF) throughout the scenario simulation, was decided by simulating it with
a smaller magnitude event. The best waveform fitting was judged with the smallest misfit value. In the second stage, near
field ground motion simulation of scenario events was performed. Calculations were achieved by considering three different
rupture processes which have the same magnitude but different asperity locations. Fault and asperity parameters for each scenario
were determined from empirical scaling laws. It has been found that the peak ground acceleration and peak ground velocities
reach maximum values of 1,440 cm/s2 and 125 cm/s, respectively for the worst case scenario. Rupture directivity effect is observed with clear peaks at a forward
station. The design spectra for Turkish seismic design code (TSDC 2007) were either nearly or actually exceeded by the scenario earthquakes at periods lower than 0.6 s at all near field stations.
Majority of structures in the area were built to lower design spectra before the 1998 code was implemented. The strength of
many structures would have been insufficient to resist the forces that may be generated by an earthquake that is similar to
Scenario I and Scenario II in this study. 相似文献
8.
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
9.
本文基于文献计量学方法,研究了我国自公元1900年以来,尤其是近35年以来的现代地震科技文献的基本特征.其中包括:文献增长速率、文献分散与集中规律、分枝学科文献分布以及地震事件对文献产出量影响等.笔者得到以下几点有意义的结论:1.70年代之后,我国地震科技文献产出量每年以32%的速率增长;2.地震学各分枝学科文献分布量和年增长量是不平衡的;3.地震文献分布服从布拉德福(Bradford)的文献离散率,和加菲尔德(Garfield)的文献集中律;4.地震文献量的增长,明显受到地震事件的影响. 相似文献
10.
Benedikt Halldorsson Ragnar Sigbjornsson Johannes Schweitzer 《Journal of Seismology》2009,13(1):173-178
A small-aperture, strong-motion array, the ICEARRAY, has been deployed in South Iceland, a region with a history of destructive
earthquakes, some exceeding magnitude 7. The array’s purpose is: (1) monitoring future significant events in the region, (2)
quantifying spatial variability of strong-motion over short distances and (3) shedding light on earthquake source processes.
The number of array stations and their arrangement were based on an optimisation of the shape of the corresponding array transfer
function (ATF). The optimal ICEARRAY configuration comprises 14 stations, has an aperture of ~1.9 km and a minimum interelement
distance of ~50 m and possesses a near-azimuthally independent ATF with a sharp main lobe, negligible sidelobes and a wavenumber
range of 1.5–24 rad/km. Accordingly, the ICEARRAY has the intended capabilities of capturing seismic waves in the frequency
range of 1–20 Hz, which is of main interest to earthquake engineering and engineering seismology applications. 相似文献
11.
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
12.
JiaJun Liu GuangJian Mao XingHua Ma LiXing Li YuQian Guo GuangZhi Liu 《中国科学D辑(英文版)》2008,51(6):769-777
Examination of ores by optical microscope and EPMA from the Zhaishang gold deposit, southern Gansu Province, has revealed an abundance of rare minerals. These include native metals, Cu-Ni-Zn-Sn-Fe polymetallic compounds and S-bearing alloys of Ni, Fe, Zn, Cu and Sn, occurring as native nickel, Zn-Cu alloy, Ni-Zn-Cu alloy, Sn-Zn-Ni-Cu alloy, Zn-Cu-Ni alloy, Zn-Fe-Cu-Sn-Ni alloy, Fe-Ni-S alloy, Sn-Fe-Ni-S alloy, Fe-Zn-Cu-Ni-S alloy, Zn-Ni-Cu-Fe-S alloy and others. Compared with the Zn-Cu alloy minerals discovered previously, these Zn-Cu minerals fall in the α or α β portion in Zn-Cu alloy phase diagram, and the α portion has higher Cu content. Cu-Ni-Zn-Sn-Fe intermetallic compounds and S-bearing alloy minerals have not been previously reported in the literature. These rare alloys formed in a strongly reducing environment with absent oxygen and low sulfur activities. 相似文献
13.
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
14.
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
15.
IntroductionMaximumentropyspectralmethod(MEM)(Burg,1972)hadbeenamethodusuallyusedinstudyingtheseismicityanditsmainpurposeistofindthedominantspectrainthelong-termseismicityprocessesinthepastyears(Zhu,1985).Inthispaper,themethodisappliedtostudywhethertherearesomespecialspectraofseismicityinsomespecificstagesinearthquake-generatingprocesses.Sowestudyseparatelythenormalandabnormalstageofearthquakeactivity,whoseactiveprocessisregardedasstablestochasticprocess,inordertofindtheirspectracharactersan… 相似文献
16.
ＰａｔｅｒｎｓａｎｄｒｅｇｕｌａｒｉｔｙｏｆｒｉｎｇｄｉｓｔｒｉｂｕｔｉｏｎｏｆｓｅｉｓｍｉｃａｃｔｉｖｉｔｙｂｅｆｏｒｅｇｒｅａｔｅａｒｔｈｑｕａｋｅｓｉｎＣｈｉｎａＳＨＩ－ＲＯＮＧＭＥＩ（梅世蓉），ＺＨＩ－ＰＩＮＧＳＯＮＧ（宋治平）ａｎｄＹＡＮ... 相似文献
17.
18.
In the list of ’repeating pairs’ or ’doublets’ of earthquakes in China identified by Schaff and Richards using tele-seismic waveform cross-correlation, there were 23 repeating pairs located in Liaoning Province. In this study the waveforms of these events were cross-correlated using records from Liaoning Regional Seismograph Network (LRSN), and the ’repeating events’ in the sense of regional waveform cross-correlation were obtained. The result was compared with that of Schaff and Richards and was used for the assessment of the seismic phase picking and event location practice of LRSN. The result shows that ’repeating events’ in the sense of teleseismic waveform cross-correlation and those in the sense of regional waveform cross-correlation have significant difference, al-though with some overlap. However, the overall assessment of the location accuracy and the phase pick errors of LRSN by using these two sets of ’repeating events’, respectively, provides similar results, while ’repeating events’ in the sense of regional waveform cross-correlation seem to be better performing in such an assessment. With the assumption that the separation between the ’repeaters’ be less than 1 km, the uncertainty in routine earthquake location of LRSN is estimated to be below 5 km, with the average of 2 km. In the observational bulletins of LRSN the time error in phase picking is estimated to be within ±1s for 94% Pg readings and for 88% Sg readings. 相似文献
19.
利用近几年在川滇地区破坏性地震及汶川地震强余震中获得的951条加速度记录, 通过选取合适的衰减关系形式和距离参数, 经统计获得了川滇地区水平向峰值加速度与35个周期点对应的加速度反应谱(阻尼比0.05)衰减关系. 统计结果显示, 震级越大, 地震动随距离的衰减越慢; 加速度反应谱的短周期部分随距离的衰减明显快于长周期部分; 中强地震在近场也会产生较大的峰值加速度和较高的短周期加速度反应谱. 由于统计资料的非完整性, 本文统计结果尚不宜直接应用于相关工程场地的设计地震动参数确定中. 但本文结果与目前由转换方法得到的我国西部地震动参数衰减规律的较大差异提示: 进一步深入研究我国地震动参数衰减规律应是紧迫而重要的任务. 相似文献
20.
On Chinese earthquake history — An attempt to model an incomplete data set by point process analysis 总被引：1，自引：0，他引：1
Since the 1950s, the Academia Sinica in Peking, People's Republic of China, has carried out extensive research on the Chinese earthquake history. With a historical record dating back some 3000 years, a wealth of information on Chinese earthquakes exists. Despite this monumental undertaking by the Academia Sinica, much work is still necessary to correct the existing earthquake data for historical changes in population, customs, modes of communication, and dynasties. In this paper we report on the status of our investigation of Chinese earthquake history and present some preliminary results. By applying point process analysis of earthquakes in Central China, we found suggestions of (1) lower earthquake activity at intervals of about 175 years and 375 years, and (2) higher earthquake activity at an interval of about 300 years. 相似文献