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1.
Statistical features of aftershock distribution size for moderate and large earthquakes in Chinese mainland 总被引：1，自引：0，他引：1
Based on data of earthquake sequences with MS≥5.0 in Chinese mainland from 1970 to 2004,for different se-quence types and different rupture modes of the main shock,the relationship between aftershock distribution size Rand the magnitude of the main shock M0 has been studied statistically.Considering the rupture mode of the mainshock,we give the quantitative statistical relationships between R and M0 under 95%confidence level for differentsequence types.Qualitatively,lgR,the logarithm of the aftershock distribution size,is positively correlative to theM0,but the data distribution is dispersed.Viewing from different sequence types,the correlation between R and M0is very weak for isolated earthquake type(IET)sequence,R distributes in the range from 5 to 60 km;For main-shock-aftershock type(MAT),lgR is positively correlative to M0;For multiple main shock type(MMT),the core-lation between lgR and M0 is not very obvious when M0≤6.2 and R distributes in the range from 5 to 70 km,whileit shows a linear correlation when M0≥6.3.The statistical results also show that the occupational ratios of differentsequence types for strike-slip and oblique slip are almost the same.But for dip-slip(mostly are thrust mechanisms),the ratio of MAT is higher than that of IET and MMT.Comparing with previous results,it indicates that,when M0is large enough,R is mainly determined by M0 and there is almost no relationship with the rupture mode of themain shock. 相似文献
2.
Summary The aftershock activity associated with the North Aegean Sea earthquake of February 19, 1968 (M
s
=7.1) has been studied with emphasis on the time and magnitude distributions. Regarding the focal mechanism it was noted that the sense of first motion remains rather unchanged throughout the sequence.The secondary series are not distinct in space or time or mechanism from the primary sequence. Although the main shock was followed by almost 3000 aftershocks (M
L
2.1) which form the basis for this study, principal strain has been released by the main shock which is responsible for the 82 per cent of total strain release in the sequence. 相似文献
3.
In this paper, the methods of pattern recognition and fuzzy cluster are applied to estimate comprehensive whether there would
be an earthquake which magnitude is commensurate with (N=M
0±0.3) or greatM>M
0) thanM
0 within 3 months using sequential data in 3 days immediately after a moderate or strong earthquake (M
0≥4.7) occurred, The result of retrospective test indicates that the comprehensive judgment effects by using these applied
mathematics methods are better than that of using every individual method obviously. TheV mark value of algorithm CORA-3 in pattern recognition is the highest among them. There are 44 known earthquake sequence data
(5 type- I and 39 type- II) used to learn and train, the results of internal coincidence test show that all 44 sequence samples
could be distinguished correctly. Extrapolation test by using other 4 known earthquake sequences (2 type- I and 2 type- II)
shows that all 4 extrapolation samples could be distinguished correctly also. In the process of study, these methods have
been applied to judge the post-earthquake tendency of 2 moderate earthquakes occurred recently, one is distinguished correctly
and the other wrong. The algorithm Hamming in pattern recognition and fuzzy cluster method have been applied to judge the
early post-earthquake tendency after a moderate or strong earthquake, too. TheV mark values of internal coincidence tests could get above 0.8 most cases of extrapolating are correct.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 15–21, 1993. 相似文献
4.
地震序列发震构造研究是区域地震活动性和地震危险性分析的重要基础。2017年3月渤海海域发生地震序列活动,该序列发生在郯城-庐江断裂带与张家口-渤海地震带的交汇部位,区域构造较为复杂。然而在渤海海域,连续运行的固定地震监测仪器难以布设,导致地震监测能力相对较弱。本文首先采用模板匹配方法对序列遗漏地震进行检测,再使用波形互相关震相检测进行震相校正,基于校正后的震相到时数据对序列进行精定位,并计算序列中2次最大地震的震源机制解。通过计算共检测到目录遗漏地震32个,约为台网目录中地震数量的1.8倍。根据波形互相关聚类分析发现渤海地震序列可分为2组,一组为M_L4.4地震及其余震序列,一组为最大震级M_L3.5的震群,另有一个M_L1.6地震与其他地震波形相似度较低,可能为一个孤立的地震事件。精定位和震源机制结果显示,2组地震均为NE走向,M_L4.4地震发生在低倾角正断层,M_L3.5地震发生在高倾角走滑断层。最后结合区域地质构造相关研究成果,认为M_L4.4地震及其余震序列发震构造为渤中凹陷内NE向低倾角的伸展性正断层,M_L3.5震群发震构造为NE向倾角较陡的次级走滑断层。 相似文献
5.
内蒙古和林格尔地处鄂尔多斯块体北缘阴山地震带内,历史上6级以上强震频发。2020年3月30日和林格尔发生M_L4.5地震,打破了自2005年以来阴山地震带M_L4.0以上地震的长期平静。研究此次地震序列的发震构造对区域应力状态和地震危险性分析有重要作用,然而内蒙古地震台网台站较为稀疏,相对于华北其他地区地震监测能力较低,对和林格尔地震序列的分析造成不利影响。本文采用匹配定位检测方法(ML)检测区域台网目录遗漏的微震,并对检测到的地震事件进行精定位。匹配定位方法共检测到序列中可定位的地震事件61个,约为台网目录的1.3倍,可定位地震约为台网目录的2.9倍。地震序列重定位结果中余震整体呈现NE向的分布,与使用CAP方法得到主震震源机制NE向节面走向基本一致,破裂为正断走滑型,显示和林格尔M_L4.5地震序列发震构造为NE走向、NW倾向的拉张性断层。结合计算结果和区域地震地质构造特征,认为M_L4.5地震序列发震构造为NE走向的岱海-黄旗海盆地南缘断裂。 相似文献
6.
The poissonian and non-fractal characters generally exhibited by the most intense natural events do not allow the application of the current exponential and power law long-term hazard predictive models, and have suggested searching for a new model. This has been set up also taking into account that the random sequence (representing disorder) of these events is linked to the duration of the stationary small ones (representing order). The model, proposed in terms of the orbit of a simple non-linear hazard function, simulates the large eruptions of Vesuvius quite well and permits estimation of the next subplinian eruption to occur there around A.D. 2030. A short range forecasting model based on the tidal triggering is also provided and discussed. When large tidally triggered M2 term in the earthquakes at Vesuvius become significant at the 0.01 level the proposed long-term hazard model will yield a more accurate estimate of the above prediction. 相似文献
7.
D. Albarello A. Berardi C. Margottini M. Mucciarelli 《Pure and Applied Geophysics》1995,145(2):297-312
A multi-parametric study of empirical relationships between macroseismic data and magnitude is presented for the Italian region by the analysis of a new extended data set concerning 146 earthquakes. The available magnitude determinations include all of the most intense earthquakes which occurred in Italy in the last century and have been obtained by an accurate revision of original instrumental data. Intensity data have been revised and upgraded on the basis of the most recent studies: only local intensities directly documented have been used. Macroseismic determinations ofM
s
,m
B
andM
wa
magnitudes have been performed. The empirical relationships between maximum felt intensity (I
max
) and magnitude have been determined by the use of a distribution-free approach and a linear regression analysis. This last parameterization allows for the explanation of more than 60% of the variation in magnitude. In order to improve these results, the linear dependence between magnitude,I
max
and average distances (in logarithm) corresponding to fixed attenuation values has been explored. The comparison between instrumental magnitudes and corresponding macroseismic estimates obtained from empirical relationships shows that the respective uncertainties are comparable. 相似文献
8.
IntroductionMore than 30 years has passed since gravity method was used to Study the eanhquake prediction in China in later 1960s (In America, Germany, Japan and the former Soviet Union etC. it haspassed nearly half a century). In this 30 years the most remarkable success achieved are as follows.First, in the cognition aspect, the questions whether the gravity will change or not before earthquake and how much the magnitUde of change has been answered. TO the fial queStion, the answer is p… 相似文献
9.
A version of the restricted trigger model is used to analyse the temporal behaviour of some aftershock sequences. The conditional
intensity function of the model is similar to that of the Epidemic Type Aftershock-Sequence (ETAS) model with the restriction
that only the aftershocks of magnitude bigger than or equal to some threshold Mtr can trigger secondary events. For this reason we have named the model Restricted Epidemic Type Aftershock-Sequence (RETAS)
model. Varying the triggering threshold we examine the variants of the RETAS model which range from the Modified Omori Formula
(MOF) to the ETAS model, including such models as limit cases. In this way we have a quite large set of models in which to
seek the model that fits best an aftershock sequence bringing out the specific features of the seismotectonic region struck
by the crisis. We have applied the RETAS model to the analysis of two aftershock sequences: The first is formed by the events
which followed the strong earthquake of M=7.8 which occurred in Kresna, SW Bulgaria, in 1904. The second includes three main shocks and a large swarm of minor shocks
following the quake of 26 September 1997 in the Umbria-Marche region, central Italy. The MOF provides the best fit to the
sequence in Kresna; that leads to the thought that just the stress field changes due to the very strong main shock generate
the whole sequence. On the contrary, the complex behaviour of the seismic sequence in Umbria-Marche appears when we make the
threshold magnitude vary. Setting the cut-off magnitude M0=2.9 the best fit is provided by the ETAS model, while if we raise the threshold magnitude M0=3.6 and set Mtr=5.0, the RETAS model turns out to be the best model. In fact, observing the time distribution of this reduced data set, it
appears more evident that especially the strong secondary events are followed by a cluster of aftershocks. 相似文献
10.
Liu Jianming Wang Qiong Nie Xiaohong Gao Ge Zhang Linlin Zhang Zhiguang Xiang Yang 《中国地震研究》2017,31(3):381-394
This paper introduces the basic parameters, focal mechanism solutions and earthquake sequence characteristics of the Kalpin MS5.3 earthquake sequence of December 1, 2013, and analyzed seismic activity before the earthquake, the adjacent tectonic features and the precursory anomaly at fixed points within a range of 200km. Research indicates:(1) The earthquake occurred on Kalpin fault, the source rupture type is thrust faulting with sinistral strike-slip component. (2) The earthquake sequence is mainshock-aftershock type, with the aftershock distribution attenuating quickly and trending NE. (3) Abnormal seismic activity before the earthquake was characterized by seismically nesting quiescence of MS2.0-4.0 earthquakes, seismic quiescence of MS4.0 earthquakes and seismic belts of MS3.0 earthquakes in the Kalpin block, abnormal enhancement zone of moderate earthquakes on Puchang fault and seismological parameters. (4) Anomalies of precursory observation data at fixed stations are mainly characterized by mutation. Apart from the borehole tiltmeter in Halajun, the spatial distribution of other abnormal precursors showed a phenomenon of migration from the near field to far field and from the epicenter to the peripheries. 相似文献
11.
中强地震发生后,地震检测因受到尾波的干扰可能会遗漏部分微震事件,影响地震目录的完备性。文章利用波形模板匹配方法对2020年新疆伽师MS6.4地震序列开展微震检测,相比原始的中国地震台网中心统一地震目录,新检测出1 756个微震事件,地震数量增加了1.3倍。基于检测后的余震目录计算最小完备震级为ML1.2,地震活动性b值为0.76,较原始目录的ML1.6和0.77均有所降低。通过伽师震源区地震序列活动特征分析,结果表明前震序列在主震前短时间内(前36小时)出现地震活动的密集增强,相应的b值显示为低值;主震发生后地震序列完备震级较高,随着时间的推移,完备震级缓慢降低并趋于稳定,并且呈周期性的波动。本研究提高了伽师震源区地震目录的完备性,为精细化描述该地区地震序列时空演化特征提供了关键数据基础。 相似文献
12.
2016年8月24日意大利中部发生MW6.0地震,2个月之后,震中附近相继发生MW5.5、MW5.9、MW6.5地震。研究这几次较大地震间的相互触发作用及机制十分必要,然而在大地震之后传统地震目录通常缺失很多余震事件,缺失的余震事件包含着早期余震时空分布和迁移规律的信息,为完善余震目录本文利用匹配滤波方法对MW6.0地震后80天内的连续数据进行余震检测,得到了数十倍于模板数量的新检测事件,检测事件与模板事件组成的新余震目录完备震级为1.0,提高了地震目录的完备性。依据新余震目录进行余震时空分布研究,结果显示MW6.0、MW5.9、MW6.5地震的早期余震迁移规律不同。MW6.0地震的早期余震沿着断裂走向同时朝两侧迁移;而MW5.9、MW6.5地震的早期余震向南、北迁移表示出不对称的特征。通过拟合余震迁移前端发现,MW6.0、MW5.5地震的早期余震朝着随后较大地震的方向迁移,且较符合lgt的特征,表明余震迁移可能与慢滑动有关。 相似文献
13.
The algorithm CN makes use of normalized functions. Therefore the original algorithm, developed for the California-Nevada region, can be directly applied, without adjustment of the parameters, to the determination of the Time of Increased Probability (TIP) of strong earthquakes for Central Italy. The prediction is applied to the events with magnitudeMM
0=5.6, which in Central Italy have a return period of about six years. The routinely available digital earthquake bulletins of the Istituto Nazionale di Geofisica (ING), Rome, permits continuous monitoring. Here we extend to November 1994 the first study made by Keilis-Boroket al. (1990b). On the basis of the combined analysis of seismicity and seismotectonic, we formulate a new regionalization, which reduces the total alarm time and the failures to predict, and narrows the spatial uncertainty of the prediction with respect to the results ofKeilis-Borok
et al. (1990b).The premonitory pattern is stable when the key parameters of the CN algorithm and the duration of the learning period are changed, and when different earthquake catalogues are used.The anlysis of the period 1904–1940, for whichM
0=6, allows us to identify self-similar properties between the two periods, in spite of the considerably higher seismicity level of the earlier time interval compared with the recent one. 相似文献
14.
Leonardo Alvarez Julio García Franco Vaccari Giuliano F. Panza Bertha González Carmen Reyes Bárbara Fernández Ramón Pico José A. Zapata Enrique Arango 《Pure and Applied Geophysics》2004,161(5-6):1041-1059
— The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Oriente fault zone is studied. Synthetic SH-waves seismograms have been calculated along four profiles in the basin by the hybrid approach (modal summation for the path source-profile and finite differences for the profile) for a maximum frequency of 1 Hz. The response spectra ratio (RSR) has been determined in 49 sites, distributed along all considered profiles with a spacing of 900 m. The corresponding RSR versus frequency curves have been classified using a logical-combinatorial algorithm. The results of the classification, in combination with the uppermost geological setting (geotechnical information and geological geometry of the subsoil) are used for the seismic zoning of the city. Three different main zones are identified, and a small sector characterized by major resonance effects, due to the particular structural conditions. Each zone is characterized in terms of its expected ground motion parameters for the most probable strong earthquake (MS=7), and for the maximum possible (MS=8). 相似文献
15.
T. C. Sharma 《水文科学杂志》2013,58(1):79-92
Abstract Two entities of importance in hydrological droughts, viz. the longest duration, LT , and the largest magnitude, MT (in standardized terms) over a desired time period (which could also correspond to a specific return period) T, have been analysed for weekly flow sequences of Canadian rivers. Analysis has been carried out in terms of week-by-week standardized values of flow sequences, designated as SHI (standardized hydrological index). The SHI sequence is truncated at the median level for identification and evaluation of expected values of the above random variables, E(LT ) and E(MT ). SHI sequences tended to be strongly autocorrelated and are modelled as autoregressive order-1, order-2 or autoregressive moving average order-1,1. The drought model built on the theorem of extremes of random numbers of random variables was found to be less satisfactory for the prediction of E(LT ) and E(MT ) on a weekly basis. However, the model has worked well on a monthly (weakly Markovian) and an annual (random) basis. An alternative procedure based on a second-order Markov chain model provided satisfactory prediction of E(LT ). Parameters such as the mean, standard deviation (or coefficient of variation), and lag-1 serial correlation of the original weekly flow sequences (obeying a gamma probability distribution function) were used to estimate the simple and first-order drought probabilities through closed-form equations. Second-order probabilities have been estimated based on the original flow sequences as well as SHI sequences, utilizing a counting method. The E(MT ) can be predicted as a product of drought intensity (which obeys the truncated normal distribution) and E(LT ) (which is based on a mixture of first- and second-order Markov chains). Citation Sharma, T. C. & Panu, U. S. (2010) Analytical procedures for weekly hydrological droughts: a case of Canadian rivers. Hydrol. Sci. J. 55(1), 79–92. 相似文献
16.
I. Rotwain G. De Natale I. Kuznetsov A. Peresan G. F. Panza 《Pure and Applied Geophysics》2006,163(1):19-39
The possibility of intermediate-term earthquake prediction at Mt. Vesuvius by means of the CN algorithm is explored. CN was
originally designed to identify the Times of Increased Probability (TIPs) for the occurrence of strong tectonic earthquakes,
with magnitude M ≥ M0, within a region a priori delimited. Here the CN algorithm is applied, for the first time, to the analysis of volcanic seismicity. The earthquakes
recorded at Mt. Vesuvius during the period from February 1972 to June 2004 are considered, and the magnitude threshold M0 selecting the events to be predicted is varied within the range: 3.0–3.3. Satisfactory prediction results are obtained, by
retrospective analysis, when a time scaling is introduced. In particular, when the length of the time windows is reduced by
a factor 2.5–3, with respect to the standard version of CN algorithm, more than 90% of the events with M ≥ M0 occur within the TIP intervals, with TIPs occupying about 30% of the total time considered. The control experiment ``Seismic
History' demonstrates the stability of the obtained results and indicates that the CN algorithm can be applied to monitor
the preparation of impending earthquakes with M ≥ 3.0 at Mt. Vesuvius. 相似文献
17.
Ｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆａｍｂｉｅｎｔｓｔｒｅｓｓｖａｌｕｅｓｆｏｒｍｉｃｒｏ－ｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅｓｉｎＷｅｓｔｅｒｎＹｕｎｎａｎ Ｅａｒｔｈｑｕａｋｅ Ｐｒｅｄｉｃｔｉｏｎ Ｅｘｐｅｒｉｍｅｎｔａｌ ＦｉｅｌｄＪｉａ－Ｚ... 相似文献
18.
A catalog for northeast India and the adjoining region for the period 1897–2009 with 4,497 earthquakes events is compiled
for homogenization to moment magnitude M
w,GCMT in the magnitude range 3–8.7. Relations for conversion of m
b and M
s magnitudes to M
w,GCMT are derived using three different methods, namely, linear standard regression, inverted standard regression (ISR) and orthogonal
standard regression (OSR), for different magnitude ranges based on events data for the catalog period 1976–2006. The OSR relations
for M
s to M
w,GCMT conversion derived in this paper have significantly lower errors in regression parameters compared to the relations reported
in other studies. Since the number of events with magnitude ≥7 for this region is scanty, we, therefore, considered whole
India region to obtain the regression relationships between M
w,GCMT and M
s,ISC. A relationship between M
w,GCMT and M
w,NEIC is also obtained based on 17 events for the range 5.2 ≤ magnitude ≤ 6.6. A unified homogeneous catalog prepared using the
conversion relations derived in this paper can serve as a reference catalog for seismic hazard assessment studies in northeast
India and the adjoining region. 相似文献
19.
Large data sets covering large areas and time spans and composed of many different independent sources raise the question
of the obtained degree of harmonization. The present study is an analysis of the harmonization with respect to the moment
magnitude M
w within the earthquake catalogue for central, northern, and northwestern Europe (CENEC). The CENEC earthquake catalogue (Grünthal
et al., J Seismol, 2009) contains parameters for over 8,000 events in the time period 1000–2004 with magnitude M
w ≥ 3.5. Only about 2% of the data used for CENEC have original M
w magnitudes derived directly from digital data. Some of the local catalogues and data files providing data give M
w, but calculated by the respective agency from other magnitude measures or intensity. About 60% of the local data give strength
measures other than M
w, and these have to be transformed by us using available formulae or new regressions based on original M
w data. Although all events are thus unified to M
w magnitude, inhomogeneity in the M
w obtained from over 40 local catalogues and data files and 50 special studies is inevitable. Two different approaches have
been followed to investigate the compatibility of the different M
w sets throughout CENEC. The first harmonization check is performed using M
w from moment tensor solutions from SMTS and Pondrelli et al. (Phys Earth Planet Inter 130:71–101, 2002; Phys Earth Planet Inter 164:90–112, 2007). The method to derive the SMTS is described, e.g., by Braunmiller et al. (Tectonophysics 356:5–22, 2002) and Bernardi et al. (Geophys J Int 157:703–716, 2004), and the data are available in greater extent since 1997. One check is made against the M
w given in national catalogues and another against the M
w derived by applying different empirical relations developed for CENEC. The second harmonization check concerns the vast majority
of data in CENEC related to earthquakes prior to 1997 or where no moment tensor based M
w exists. In this case, an empirical relation for the M
w dependence on epicentral intensity (I
0) and focal depth (h) was derived for 41 master events, i.e., earthquakes, located all over central Europe, with high-quality data. To include
also the data lacking h, the corresponding depth-independent relation for these 41 events was also derived. These equations are compared with the
different sets of data from which CENEC has been composed, and the goodness of fit is demonstrated for each set. The vast
majority of the events are very well or reasonably consistent with the respective relation so that the data can be said to
be harmonized with respect to M
w, but there are exceptions, which are discussed in detail. 相似文献
20.
2018年9月4日新疆伽师发生MS5.5地震,震中处于塔里木地块西北缘,位于1997~1998年伽师强震群震区内。此次伽师地震前发生了MS4.7前震,截至9月30日最大余震震级为MS4.6（ML5.0）,初步判定为前-主-余型地震序列。序列精定位结果显示,余震沿近NE向展布,主震震源深度与1997~1998年伽师强震主震基本一致,发震断层陡立。本文从区域的构造环境、地震震源机制解和余震分布特征等方面分析认为,地震发生在伽师隐伏断裂东南端部,为1997~1998年伽师强震群震区的一次新的构造活动。序列参数、视应力等计算结果显示,伽师MS5.5地震的预测最大余震震级与最大余震震级MS4.6接近,表明序列最大余震已经发生。 相似文献