京棉二厂井氦、氢气体的地震前兆异常特征及与地震关系的研究.

系统总结了京棉二厂热水深井溶解气体中氦、氢气体异常变化与地震的关系,提出了氦、氢气体前兆异常特征与发震时间、震级关系的经验公式.用此经验公式较成功地预报了华北两次5级以上地震,具有一定的实用意义.      

山西夏县疗1号井氦异常与映震效能初析

对山西夏县疗 1号井 1 992年以来逸出气的观测资料进行了追踪研究 ,结果表明 ,夏县疗 1号井 1 997年 8月的氦异常不仅与 1 998年山西地震带上 5级以上地震有关 ,可能还反映了华北地区应力场的增强过程     

聊古-井逸出气氦数字化观测资料分析及其映震能力的初步研究

简要介绍了一种新型测氦仪-GWK-201型测氦仪，分析了聊古一井1998年9月1日～1999年11月30日的逸出气氦观测资料。结果表明：该资料的正常动态为近直线型，并且在附近4.0级地震前有显的异常显示，对今后的地震预报探索研究具有一定的参考价值。     

华北地下释放氦、氢气体异常的时、空、强特征及其与地震关系的探讨

在系统整理华北９个气体观测井多年观测资料基础上，初步探讨了华北地下释放氦、氢异常的时、空、强特征及其与发震时间、地点、震级的关系，从而总结为以京棉二厂井的氦、氢异常为依据，其它测点的氦、氢异常为参考，预报华北北部５级以上地震的初步经验     

GWK-201型测氦仪及其观测资料分析

简要介绍了一种新型测氦仪———GWK - 2 0 1型测氦仪 ,分析了聊古一井 1998年 9月 1日至 1999年 11月 30日的逸出气氦观测资料。结果表明 :该资料的正常动态为近直线型 ,并且在附近 4 0级地震前有显著的异常显示 ,对今后的地震预报研究具有一定的参考价值     

大姚水温动态异常与地方震的对应

通过对大姚高精度水温1986年观测以来100km范围内发生5．0级以上地震前后的水温动态特征分析，结果表明大姚水温动态在地方震前基值上升，周期变化形态消失或畸变，震时有同震反应，震后存在震后效应，水温动态具有震前异常变化明显且多为短临异常的特点，对观测井周围的地方震预测具有较高的实用价值。初步探讨了水温动态异常的可能原因。     

云南M≥5地震震前异常的统计特征

通过对1970年以来云南38组M≥5地震震前异常的综合分析,得到云南5级以上地震的异常共性特征:震前小震频度普遍增强;6级以上地震的异常持续时间比5级地震长;异常分布越广可能未来地震的震级越大;部分前兆观测项目趋势异常结束、新的突变异常增多,是地震孕育进人短临阶段的标志.     

聊古一井氦异常与地震的关系

处理了聊古一井1981 ～1984 年氦的观测资料,发现在两次较近的地震(1981 年宁晋MS5 .8 和1983 年菏泽MS5 .9) 前,氦都有明显的形态相似的异常变化.     

中国大陆第5地震轮回青藏块体强震活动特征

1977年以来（中国大陆第5地震轮回）青藏块体发生11次7级以上地震,分析7级以上地震及地震前5级以上地震活动特征,结果表明,7级以上主震发生前,震中区5级以上地震活动一般存在20年以上的平静异常,地震活动特征差异与主震震源机制解及构造位置密切相关。     

古浪—海原断裂带“无震异常”的意义

近年来,在监视预报地震的实践中,经常遇到有显著前兆异常而无近震与之对应的情况,此即所谓“无震异常”。1979年冬至1980年春,我省靖远—天祝一带出现一批地下水动态异常,异常之强烈及其展布范围之大,为近十年来所罕见,同时伴有一些其它前兆异常现象,但至今该地区没有发生5级以上地震。     

A Morphostructural Zoning of the Mountainous Crimea and the Possible Locations of Future Earthquakes

The locations of possible earthquake occurrence (magnitudes M ≥ 6) have been determined for mountainous Crimea and the adjacent sea shelf, including the continental slope zone. The earthquake-generating structures were assumed to be intersections of morphostructural lineaments as found by morphostructural zoning. The measurement of geological and geophysical characteristics was followed by applying a decision rule that was derived previously using the CORA-3 pattern recognition algorithm in order to find possible locations of M ≥ 6 earthquakes in the Caucasus. The results corroborate the high seismic potential for the Yalta area where two events with magnitudes of 6.0 and 6.8 occurred in 1927, as well as indicating the possibility of M ≥ 6 earthquakes in other areas in mountainous Crimea and in the adjacent Black Sea area where no such events have yet been recorded.     

Spatiotemporal distributions of earthquakes in the northeastern segment of the Amur plate in two phases of variations in the modulus of the Earth’s rotation rate

The modeling results are presented on the annual dynamics of seismicity in the northeastern segment of the Amur plate, which are obtained from statistical studies of the number of earthquakes with magnitudes 2 ≤ М ≤ 6 in different phases of variations in the Earth’s rotation rate. We have calculated a degree of relationship between the observed seismicity variations and phases of decrease and increase in the Earth’s rotation rate for the magnitude ranges between 2 ≤ М < 4 and 4 ≤ М < 5 using rank correlation methods. It has been established that epicenters of earthquakes with magnitudes 5 ≤ М ≤ 6 are spatially grouped into a sequence of homogeneous equally spaced, 3.5°–4°, on average, east-westerly oriented clusters.     

聊古—井水氡正常动态的探讨

采用相关距平法和增均值法对聊古－井１２年的水氡预测资料进行了处理和分析。从定性、定量两方面描述了聊古－井水氡预测资料的正常年动态呈近直线型。并且从本井水文地球化学背景、阐述了分析、判断水氡测值异常的机理,为本区或邻区地震的预测预报,提供了依据。     

A statistical analysis of upper and lower limits of earthquake magnitude

The relationship between frequency and magnitude in homogeneous series of earthquakes is studied. The linear relation of Gutenberg and Richter between the logarithm of frequency and the magnitude is found to be applicable only in a restricted range of magnitudes.The plots of the cumulative number of earthquakes versus magnitude for 20 different series (the total number of events in a single series ranging from about 50 to more than 3000) clearly indicate the presence of vertical asymptotes. This fact suggests that upper and lower limits could exist for the magnitude of a single event, i.e. for the energy that can be released in an earthquake. From the position of the vertical asymptotes it is possible to obtain the upper and lower bounds of magnitude for each series of earthquakes. The empirical shape of the cumulative number-magnitude distribution can be well represented by equilateral hyperbolas. A least ² method has been used to obtain the best-fitting hyperbolas and corresponding the minimum and maximum magnitudes for each series.The shape of the frequency-magnitude relationship is discussed in lesser detail. It is found, however, that after suitable rescaling the earthquakes in each series follow much the same law, with a comparatively small scatter.     

The probability of occurrence of largest earthquakes in the European area

Summary TheGumbel's theory of largest values has been applied to the estimation of probability of occurrence and of return periods of largest earthquakes in the European area. For this study shallow shocks from the period 1901–1955 and from 15 earthquake zones were used. For each zone the largest magnitudes corresponding to one-year intervals were arranged in order of increasingM, grouped in classes and then the probabilitiesF(x _j) were calculated. The data plotted on the probability paper fit a straight line fairly well. The extrapolated lines yield the possibility of estimating large magnitudes which will be exceeded with a given probability, e.g. 1%. Such values were compared with largest magnitudes observed during the period 1901–1955. Their return periods indicate that in most regions the largest probable shock already occurred. Following the procedure ofEpstein-Lomnitz the coefficients and were calculated and compared with corresponding values ofa andb of the magnitude-frequency relation.     

Characteristics of Seismicity in the Areas of Large Water Reservoirs and Waterfalls: The Role of Effects from Additional Load and Permanent Vibration

The characteristics of seismicity in the near vicinity of five large water reservoirs and three large waterfalls from different regions of the Earth are considered. It is found that in some cases induced seismicity manifests itself during the filling of reservoirs at quite large depths: in the lower crust and even in the upper mantle. There is negative correlation between the maximum magnitudes Мmax of the earthquakes recorded near water reservoirs and waterfalls and the water discharge in these objects (V _p ). The largest values of М_max are characteristic of earthquakes that occurred near Sarez Lake (Tajikistan) and the Koyna Reservoir (India), which have the lowest V _p ; in contrast, the smallest magnitudes are reported for earthquakes in the areas of the Khone Falls (Laos) and Niagara Falls (United States, Canada), where there are no large artificial water reservoirs, but huge water discharge takes place. The available data indicate that permanent vibration caused by falling water reduces the level of seismicity.     

Uncertainties in the estimation of earthquake magnitudes in Greece

Instrumental magnitudes in Greece have been reported as: a) Mmagnitudes based on the records of the Wiechert or Mainka seismographs,b) M_LGR magnitudes based on the records of the Wood-Anderson(WA) seismographs (T_o = 0.8 sec, V_effective 1000) or othershort period seismographs calibrated against WA records and,c) M_LSM magnitudes based on strong motion records(accelerograms). Comparison of such magnitudes with momentmagnitudes, M_w, for 329 earthquakes, with epicenters in thebroader Aegean area, performed in this study, showedthat M, M_LGR+0.5 and M_LSM are practically equalto M_w, with a small overall standard error ( = 0.23).Therefore, equivalent moment magnitudes, M_w ^*,estimated from these magnitudes and reported in the catalogues of theGeophysical Laboratory of the University of Thessaloniki are equal tomoment magnitudes for all practical purposes with reasonable uncertainties.It has been further shown that surface wave magnitudes, M_s,for M_s <6.0, can be also transferred into momentmagnitudes, M_w ^*, but the larger uncertaintiesencountered make its use rather problematic.     

Test of the EEPAS Forecasting Model on the Japan Earthquake Catalogue

The EEPAS (Every Earthquake a Precursor According to Scale) model is a method of forecasting earthquakes based on the notion that the precursory scale increase () phenomenon occurs at all scales in the seismogenic process. The rate density of future earthquake occurrence is computed directly from past earthquakes in the catalogue. The EEPAS model has previously been fitted to the New Zealand earthquake catalogue and successfully tested on the California catalogue.Here we describe a further test of the EEPAS model in the Japan region spanning 1965–2001, initially on earthquakes with magnitudes exceeding the threshold value 6.75. A baseline model and the Gutenberg-Richter b-value were fitted to the JMA catalogue over the learning period 1926–1964. The performance of EEPAS, with the key parameters unchanged from the New Zealand values, was compared with that of the baseline model over the testing period, using a likelihood ratio criterion. The EEPAS model proved superior. A sensitivity analysis shows that this result is not sensitive to the choice of the learning period or b-value, but that the advantage of EEPAS over the baseline model diminishes as the magnitude threshold is lowered. When key model parameters are optimised for the Japan catalogue, the advantage of EEPAS over the baseline model is consistent for all magnitudes above 6.25, although less than in the New Zealand and California regions.These results add strength to the proposition that the EEPAS model is effective at a variety of scales and in a variety of seismically active regions.     

Detailed Study of Time Variations in the Gutenberg–Richter <Emphasis Type="Italic">b</Emphasis>-value Based on Highly Accurate Seismic Observations at the Garm Prognostic Site,Tajikistan

The time variations in the Gutenberg–Richter b-value are minutely studied based on the data of highly accurate seismological observations at the Garm prognostic site, Tajikistan, where a stationary network of seismic stations of the Complex Seismological Expedition (CSE) of Schmidt Institute of Physics of the Earth (IPE) of the USSR (Russian) Academy of Sciences was in operation from 1955 to 1992. A total of 93035 local earthquakes ranging from 0.0 to 6.3 in the Ml magnitudes are considered. The spatiotemporal fluctuations in the minimal magnitude of completeness of the earthquakes, Mc, are analyzed. The study considers a 25-year interval of the observations at the center of the observation system within which Mc = 0.9. It is shown that in most cases, the b-value and log₁₀E^2/3 experience characteristic time variations before the earthquakes with magnitudes higher than the minimal magnitude of the predicted earthquake (MPE). The 6-year anomaly in the parameters’ b-value, log₁₀E^2/3, and log₁₀N associated with the single strongest earthquake with M = 6.3 that occurred in the observation region on October 26, 1984 is revealed. The inversely proportional relationship is established between the time variations in the b-value and the time variations in the velocities of seismic waves Vp and Vp/Vs. It is shown that the exponent p in the power function which links the time variations of the b-value and log₁₀E^2/3 is higher in the zones of crustal compression than in the zones of extension. It is simultaneously confirmed that the average b-value in the zones of compression is lower than in the zones of extension. It is established that in the case of earthquakes with M ≥ 2.6, the time series of seismic activity log₁₀N_i and the time series of the b-value are highly cross correlated with a coefficient of r ≈ 0.75, whereas in the case of earthquakes with M ≥ 0.9, the coefficient of cross correlation between these time series is close to zero (r ≈ 0.06). The law of variations in the slope of the lines approximating the relationship between the log₁₀N_i time series in the different magnitude ranges (M ≥ Mc_i) and b-value time series is obtained. It is hypothesized that the seismic activity of the earthquakes with high magnitudes can be estimated provided that the parameters of the time series of the b-value and time series of the number of earthquakes logN(ΔM_i) in the range of low magnitudes are known. It is concluded that using the parameter log₁₀N for prognostic estimates of the strong earthquakes only makes sense for earthquakes having moderate and large magnitudes. It is inferred that the time variations in the b-value are predominantly contributed by the time variations of the earthquakes with relatively large magnitudes.     

The French seismic CATalogue (FCAT-17)

In regions that undergo low deformation rates, as is the case for metropolitan France (i.e. the part of France in Europe), the use of historical seismicity, in addition to instrumental data, is necessary when dealing with seismic hazard assessment. This paper presents the strategy adopted to develop a parametric earthquake catalogue using moment magnitude M_w, as the reference magnitude scale to cover both instrumental and historical periods for metropolitan France. Work performed within the framework of the SiHex (SIsmicité de l’HEXagone) (Cara et al. Bull Soc Géol Fr 186:3–19, 2015. doi: 10.2113/qssqfbull.186.1.3) and SIGMA (SeIsmic Ground Motion Assessment; EDF-CEA-AREVA-ENEL) projects, respectively on instrumental and historical earthquakes, have been combined to produce the French seismic CATalogue, version 2017 (FCAT-17). The SiHex catalogue is composed of ~40,000 natural earthquakes, for which the hypocentral location and M_w magnitude are given. In the frame of the SIGMA research program, an integrated study has been realized on historical seismicity from intensity prediction equations (IPE) calibration in M_w detailed in Baumont et al. (submitted) companion paper to their application to earthquakes of the SISFRANCE macroseismic database (BRGM, EDF, IRSN), through a dedicated strategy developed by Traversa et al. (Bull Earthq Eng, 2017. doi: 10.1007/s10518-017-0178-7) companion paper, to compute their M_w magnitude and depth. Macroseismic data and epicentral location and intensity used both in IPE calibration and inversion process, are those of SISFRANCE without any revision. The inversion process allows the main macroseismic field specificities reported by SISFRANCE to be taken into account with an exploration tree approach. It also allows capturing the epistemic uncertainties associated with macroseismic data and to IPEs selection. For events that exhibit a poorly constrained macroseismic field (mainly old, cross border or off-shore earthquakes), joint inversion of M_w and depth is not possible, and depth needs to be fixed to calculate M_w. Regional a priori depths have been defined for this purpose based on analysis of earthquakes with a well constrained macroseismic field where joint inversion of M_w and depth is possible. As a result, 27% of SISFRANCE earthquake seismological parameters have been jointly inverted and for the other 73% M_w has been calculated assuming a priori depths. The FCAT-17 catalogue is composed of the SIGMA historical parametric catalogue (magnitude range between 3.5 up to 7.0), covering from AD463 to 1965, and of the SiHex instrumental one, extending from 1965 to 2009. Historical part of the catalogue results from an automatic inversion of SISFRANCE data. A quality index is estimated for each historical earthquake according to the way the events are processed. All magnitudes are given in M_w which makes this catalogue directly usable as an input for probabilistic or deterministic seismic hazard studies. Uncertainties on magnitudes and depths are provided for historical earthquakes following calculation scheme presented in Traversa et al. (2017). Uncertainties on magnitudes for instrumental events are from Cara et al. (J Seismol 21:551–565, 2017. doi: 10.1007/s10950-016-9617-1).