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1.
大地震重复特征与平均重复间隔的取值问题   总被引:20,自引:3,他引:17       下载免费PDF全文
冉勇康  邓起东 《地震地质》1999,21(4):316-323
对延怀盆地及海原断裂古地震的详细研究表明,大地震的重复行为具有多样性。特征地震是大多数断裂活动的行为特征,但特征地震存在分级性,大地震的重复时间间隔存在分阶段性,以及断裂的相互作用会影响大地震的复发序列。因此,当大地震重复行为出现时间上的分阶段性,或特征地震分级现象导致不同强度的古地震间隔时间有明显差别时,用确定性或时间相依的概率方法评价大地震的危险性,需要分阶段或分级计算不同间隔阶段的平均值  相似文献   

2.
Through study on trenches, analysis of recurrence characteristics and recurrence interval cluster/gap of strong earthquakes along the major active faults on the northern border of Ordos block, we found 62 paleoearthquakes that occurred in the late Quaternary, including 33 earthquakes occurring in the Holocene. The recurrence characteristics of the paleoearthquakes are different at three levels, segments, faults, and fault zones. The strong seismic sequence on the independent segments is mostly characterized by long- and short-interval recurrences, while that on the faults and in fault zone is characterized clearly by random and cluster recurrences. Results of the moving window test indicate that the probabilities of "temporal cluster or gap", caused by random coincidence as opposed to intersegment contagion, are 64% and 70% for the Serteng piedmont fault and for the south-border fault of Wula Mountains, respectively, no clear interaction among the segments of each fault; while the probability is 26.8% for the whole fault zone, suggesting a clear interaction among the faults of this fault zone. These recurrence characteristics may imply an effect of the entire block motion on the recurrence of strong earthquakes. Moreover, the elapsed time for the Wujumeng Pass-Dongfeng Village segment of Serteng piedmont fault and the Tuzuo Banner-Wusutu and the Hohhot segments of Daqingshan piedmont fault has exceeded the average recurrence interval, hence these three segments may be the possible places for future strong earthquakes.  相似文献   

3.
Through study on trenches, analysis of recurrence characteristics and recurrence interval cluster/gap of strong earthquakes along the major active faults on the northern border of Ordos block, we found 62 paleoearthquakes that occurred in the late Quaternary, including 33 earthquakes occurring in the Holocene. The recurrence characteristics of the paleoearthquakes are different at three levels, segments, faults, and fault zones. The strong seismic sequence on the independent segments is mostly characterized by long- and short-interval recurrences, while that on the faults and in fault zone is characterized clearly by random and cluster recurrences. Results of the moving window test indicate that the probabilities of “temporal cluster or gap”, caused by random coincidence as opposed to intersegment contagion, are 64% and 70% for the Serteng piedmont fault and for the south-border fault of Wula Mountains, respectively, no clear interaction among the segments of each fault; while the probability is 26.8% for the whole fault zone, suggesting a clear interaction among the faults of this fault zone. These recurrence characteristics may imply an effect of the entire block motion on the recurrence of strong earthquakes. Moreover, the elapsed time for the Wujumeng Pass-Dongfeng Village segment of Serteng piedmont fault and the Tuzuo Banner-Wusutu and the Hohhot segments of Daqingshan piedmont fault has exceeded the average recurrence interval, hence these three segments may be the possible places for future strong earthquakes.  相似文献   

4.
时间相依的地震危险性概率评估方法是最近10a来逐渐发展起来的,是一种将已获得的定量地质资料运用于活动断裂中—长期地震潜势概率评估的方法,从而使得在缺乏历史记载或仪器记录资料,但已获得断层平均滑动速率、同震位错、古地震年代序列等资料的活动断裂段上评估未来的发震概率成为可能。在定量计算活动断裂未来地震危险性的过程中,作为输入参数之一的特征地震平均复发间隔是一个至关重要的参数,它的确定将直接影响到概率计算的结果。对研究断裂上已获得的历史地震资料(H)、地质资料(G)和古地震资料(P),笔采用了时间可预报(T)和准周期(Q)两种模式分别计算其平均复发间隔,比单一的只假定一种复发模式计算更具有完善性和可靠性。在叙述该方法的同时,以西秦岭北缘断裂为例,详细阐述了该断裂上特征地震平均复发间隔的确定,并在此基础上对西秦岭北缘断裂未来地震潜势作了定量评估。  相似文献   

5.
川滇地区若干活动断裂带整体的强地震复发特征研究   总被引:15,自引:0,他引:15  
我们根据历史地震资料,采用统计学方法研究了川滇地区7条活动断裂带整体的强地震复发特征。结果表明,这7条断裂带的强地震复发表现出趋于随机的、随机的、以及丛集的行为,复发过程不具有良好的准周期性,也不存在强度-时间或者时间-强度的相依性。组成断裂带的强震破裂段落的数量越多,复发过程就越复杂。相对的地震活跃期与平静期交替出现。其中,活跃期内地震复发间隔分布的离散性较大,可用Weibull分布近似描述;而平静期的持续时间分布的离散性较小,可用正态等分布近似描述。不同相对活跃期的持续时间及强震的数量差别很大,导致相对活跃期并非准周期重视。因此,基于断裂带整体强震复发间隔分布的中长期危险性概率评估仍然面临一定的困难。  相似文献   

6.
Spatial distribution of sources of strong and large earthquakes on the Xiaojiang fault zone in eastern Yunnan is studied according to historical earthquake data. 7 segments of relatively independent sources or basic units of rupture along the fault zone have been identified preliminarily. On every segment, time intervals between main historical earthquakes are generally characterized by “time-predictable” recurrence behavior with indetermination. A statistic model for the time intervals between earthquakes of the fault zone has been preliminarily established. And a mathematical method has been introduced into this paper to reckon average recurrence interval between earthquakes under the condition of having known the size of the last event at a specific segment. Based on these, ranges of the average recurrence intervals given confidence have been estimated for events of various sizes on the fault zone. Further, the author puts forward a real-time probabilistic model that is suitable to analyze seismic potential for individual segments along a fault zone on which earthquake recurrence intervals have been characterized by quasi-time-predictable behavior, and applies this model to calculate conditional probabilities and probability gains of earthquake recurring on the individual segments of the Xiaojiang fault zone during the period from 1991 to 2005. As a consequence, it has shown that two parts of this fault zone, from south of Dongchuan to Songming and from Chengjiang to Huaning, have relatively high likelihoods for strong or large earthquake recurring in the future. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 322–330, 1993.  相似文献   

7.
The conventional radiocarbon ages of soil horizons limiting the timing of six fault-generating dis- placements within the East Sayan structure of the Main Sayan Fault and four displacements within the Tora structure of the Tunka Fault (M > 7) have been calibrated according to the IntCal04 calibration curve. It was revealed that between time periods of 12 Ka and 5.4 Ka years ago, the recurrence of earthquakes associated with movements along the faults in the East Sayan structure occurred once every 3000 years. After seismic quiescence, since 1100 years, one earthquake has occurred every 440 years. Using the Monte Carlo method, the possibility of the recurrence of strong earthquakes at different probability levels was considered. At a fre- quency probability of 95% the Main Sayan fault may be hazardous, dating from about 2120 AD. When low- ering the threshold probability to 72%, the beginning of the period of potential hazard is reduced to about 2030 AD. In both cases the maximum possibility of the occurrence of the next strong earthquake is not earlier than in the 22nd century. For the Tora structure, the periodicity of the recurrence of the earthquakes was esti- mated as 2800 yearsfor the past 11Ka with a probability of over 95% of the recurrence of earthquakes. This allows us to assume that currently the Tora structure is within the time interval of the potential risk of the recurrence of a strong earthquake.  相似文献   

8.
Introduction The behavior of ground water is influenced by many factors, such as rainfall, exploitation ofground water, atmospheric pressure, tidal gravitation, ground stress variation, effect of surfacewater-body loads (or other loads) and other unknown factors. These factors change the dynamicstate of ground water to different extents and result in the diversification of ground water behavior.As for their mechanism, our knowledge is still superficial. Based on various images of water le…  相似文献   

9.
准时间可预报复发行为与断裂带分段发震概率估计   总被引:7,自引:0,他引:7  
闻学泽 《中国地震》1993,9(4):289-300
反不确定性引入“时间可预报模式”,可将一次地震之后的平静时间表示成与这次地震位错量在小呈正相关的随机变量。称这种带有不确定性的地震原地复发行为为“准时间可预报行为”。对于历史地震资料,准时间可预报复发行为可由地震后平静时间的对数与地震烈度的回归方程。文中给出了估计一条枯断裂带不同段落以上一次地震烈度值为背景的平均复发时间间隔的方法,以及可用 于对未来地震潜势进行不确定评价的实时概率模型,并以鲜水河  相似文献   

10.
HUI Chun  PAN Hua  XU Jing 《地震地质》2018,40(4):861-871
It is of great significance to determine the factors and causes that affect the recurrence of major earthquakes. This paper introduces the influence of strong earthquake on the recurrence of major earthquakes according to elastic rebound theory, and then proposes to calculate the impact time Δt respectively from the effect of strong earthquakes on the same and surrounding faults on the major earthquake recurrence by using seismic moment release rate method and Coulomb stress change. In this paper, we studied the change amount of major earthquake recurrence by taking four earthquakes with magnitude greater than 6.5 occurring at different fracture sections of the Xianshuhe fault zone as an example, they occurred on Daofu, Changcu, Zhuwo Fault, respectively. We used seismic moment rate method to calculate the impact time Δt of strong earthquake on the recurrence of major earthquakes on the Daofu-Qianning Fault. We further discussed the effect of the Coulomb stress change due to the interaction between faults on the recurrence of subsequent major earthquakes. The co-seismic and post-seismic Coulomb stress changes caused by strong earthquake on the surrounding faults on the Ganzi-Luhuo Fault are calculated. With the fault interaction considered, the importance of the interaction between faults in the middle-north section of the Xianshuihe fault zone to change the recurrence of large earthquakes is retested and evaluated. The results indicate that the two strong earthquakes occurring along Xianshuihe Fault in 1904(M=7.0) and 1981(M=6.9) resulted in a delay of 80 years and 45 years of major earthquake recurrence on the Daofu-Qianning Fault respectively, and the M7.3 earthquake in 1923 and the M6.8 earthquake in 1967 resulted in an advance of 35 years of major earthquake recurrence on the Ganzi-Luhuo Fault.  相似文献   

11.
The recurrence interval statistics for regional seismicity follows a universal distribution function, independent of the tectonic setting or average rate of activity (Corral, 2004). The universal function is a modified gamma distribution with power-law scaling of recurrence intervals shorter than the average rate of activity and exponential decay for larger intervals. We employ the method of Corral (2004) to examine the recurrence statistics of a range of cellular automaton earthquake models. The majority of models has an exponential distribution of recurrence intervals, the same as that of a Poisson process. One model, the Olami-Feder-Christensen automaton, has recurrence statistics consistent with regional seismicity for a certain range of the conservation parameter of that model. For conservation parameters in this range, the event size statistics are also consistent with regional seismicity. Models whose dynamics are dominated by characteristic earthquakes do not appear to display universality of recurrence statistics.  相似文献   

12.
地震时空影响域、复发间隔和有效孕震时间   总被引:1,自引:0,他引:1  
王绳祖  张宗淳 《中国地震》2001,17(4):364-377
研究表明,地城的时空影响域(影响范围)在t(时间)-r(距离)坐标上具有双曲线型的边界曲线,t=0时的最大影响半径为r0,r=0时的最大影响时间(即原地复发间隔)为t0。根据我国华北,西北,青藏和西南地区后继地震相对于无发地震的时,距分布状况,经优化拟合和统计分析,确定了地震时空影响域的优化边界曲线及90%置信度边界曲线。以三维(时间-距离-震级)的“地震时空影响域”概念取代一维(时间)或二维(时间-震级)的“复发间隔”概念,为认识地震活动涨落起伏的实质,估计潜在震源的有效震孕震时间和改进地城的中长期预测提供了新的思路。  相似文献   

13.
祁连山-河西走廊西段构造区发育多条重要活动断裂,多年来已积累较丰富的古地震研究的成果.本文在前人研究基础上,结合历史地震数据等,从定量化强震复发间隔T与平均复发间隔Ta入手,将其比值(T/Ta)进行数学处理,借鉴NB模型的思路,建立祁连山-河西走廊西段构造区模型,进而对强震潜势进行评估.结果表明:祁连山-河西走廊西段构...  相似文献   

14.
IntroductionStrongorlargeearthquakesoccurredalongaspecificsegmentofanactivefaultarecalledsegment-rupturingearthquakes.Suchearthquakesoccurrepeatedlyatpreviouslocations.Thecurrentrecurrencemodelsforearthquakesrepeatedatpreviouslocationswereproposedonlimiteddatafromcharacteristicearthquakesonplateboundaries,mainlyincludingthetime-predictableandslippredictablemodels(Shimazaki,Nakata,1980),thequasi-periodicmodel(Bakun,McEvilly,1984;Savage,Cockerham,1986),andthetime-andmagnitude-predictablemodel…  相似文献   

15.
兰州附近的庄浪河断裂和白银白杨树沟断裂是对兰州市地震安全有一定影响的晚第四纪活动断裂,但沿断裂发生的中强破坏性地震较为复杂甚至不明确。如何评价西部地区此类断裂的最大潜在地震震级及其危险性是地震中长期预测和地震区划研究中较为重要的问题之一。本文借鉴闻学泽等(2007)对中国大陆东部中-弱活断层潜在地震最大震级评估的思路,建立了兰州地区最大地震震级Mmax与断层小区震级-频度关系参数at/b值之间的经验公式;并采用经验公式外推得到庄浪河断裂和白杨树沟断裂的震级上限Mu分别为MS6.9、6.3,进而评估了这两条断裂的地震平均复发间隔和发震概率。  相似文献   

16.
By analyzing the relationship between ground water behavior and strong seismic activity during the past more than 20 years in North China, we have found similar water level descending variation of a part of wells in the short-term stage before several strong earthquakes. The characteristics of anomaly are: at the beginning, water level dropped abruptly or accelerated to drop; then it turned to slow rising with a smaller amplitude than that of descending; earthquakes occurred during the slow-rising process of water level, and at that time or before earthquake occurrence, water level rose with a large amplitude. Among more than 100 wells in North China, the descending anomalies were not recorded for many times, but similar variation processes of water level were noted at different wells before several strong earthquakes, which proves that seismic precursory anomalies of ground water are of certain recurrence features, occurring repeatedly before different strong earthquakes. Therefore, it is necessary to study the genesis of this type of anomaly and its relationship with strong seismic activity. Foundation item: Key project of Ministry of Science and Technology during the Tenth Five-year Plan (2001BA601B 01-01-01).  相似文献   

17.
We present a Bayesian method that allows continuous updating the aperiodicity of the recurrence time distribution of large earthquakes based on a catalog with magnitudes above a completeness threshold. The approach uses a recently proposed renewal model for seismicity and allows the inclusion of magnitude uncertainties in a straightforward manner. Errors accounting for grouped magnitudes and random errors are studied and discussed. The results indicate that a stable and realistic value of the aperiodicity can be predicted in an early state of seismicity evolution, even though only a small number of large earthquakes has occurred to date. Furthermore, we demonstrate that magnitude uncertainties can drastically influence the results and can therefore not be neglected. We show how to correct for the bias caused by magnitude errors. For the region of Parkfield we find that the aperiodicity, or the coefficient of variation, is clearly higher than in studies which are solely based on the large earthquakes.  相似文献   

18.
张国民 《地震地质》1996,18(1):17-24
前人的工作曾给出大地震的强余震活动持续时间与大地震的重复时间之间存在正变化关系,即较长的余震持续时间对应较长的主震复发时间。应用地震孕育的流变模型,推导了大地震重复时间和大震后余震活动持续时间的数学表达式,并从理论上给出了大震重复时间和其余震持续时间之间的对数正比关系,从而为建立大地震的重复时间和余震持续时间的关系提供了一方面理论依据  相似文献   

19.
The Zhuanglang river and Baiyin Baiyangshu river faults are late Quaternary faults near Lanzhou city,which pose a threat to the safety of the city. However,the cause of medium-strong earthquakes along the fault is rather complicated and even uncertain. It is important for us how to assess the magnitudes of maximum potential earthquakes and the seismic risk of the faults. The authors make reference to the method that Wen Xueze,et al.(2007) developed to assess the magnitudes of maximum potential earthquakes in sub-areas of moderately and weakly active faults in the eastern Chinese Mainland,and brought forward an empirical relationship between the maximum magnitudes M_max and the a_t/b values of the sub-areas' frequency-magnitude relationships in the Lanzhou area. By using this empirical relationship,the authors have estimated the upper-limits M_u of the Zhuanglang river and Baiyin Baiyangshu river active faults near Lanzhou city as M_S6.9 and 6.3,respectively. In addition,they have assessed the average interval recurrence time and the probabilities of destructive earthquakes on the faults.  相似文献   

20.
连尉平  李丽  唐方头  胡彬  李晓璇 《地震学报》2014,36(6):1010-1021
本文构建一种应用有限元开展特征地震数值模拟的新方法, 并以龙门山断裂带中段的浅层构造和动力学机制为背景, 研究了平行逆冲断层分布格局对区域地震活动性的影响. 结果表明, 从断层活动相互影响的角度看, 包含3条平行逆断层的断裂带的整体地震活动性并不适用严格周期的特征地震模型, 当断层间距在20 km以下时, 随着断层间距的缩短, 对单条断层应用特征地震模型的适用性会逐渐降低. 龙门山断裂带中段的模拟计算结果显示, 后山断裂的地震活动相对独立, 区域活动性和中央断裂的断层活动很可能不适用严格周期的特征地震模型.   相似文献   

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