1994年河北省及华北地区震情

１９９４年河北省及华北地区震情１河北省地震活动概况１．且据我省地震台网测定，１９９４年１月１日至１９９４年１２月３１日共发生大小地震１１７８次，最大地震为１９９４年１０月４日唐山ＭＬ３．８级地震。其中ＭＬ＜２．０级地震９５７次，２．０～２．９级地震２...     

1994年震情述评

１９９４年震情述评丁鉴海，刘杰（中国北京１０００３６国家地震局分析预报中心）１１９９４年我国地震活动实况１９９４年我国共发生人Ｍｓ≥５．０级地震４８次（大陆及近海地区２９次，台湾地区１９次），其中Ｍｓ≥６．０级地震９次（大陆及近海地区４次，台湾地区５...     

1994年7—9月的全球地震动态

１９９４年第三季度，全球地震活动仍维持中等水平，西南太平洋的瓦努阿图群岛发生７．４级地震。美国加州北部海域发生７．０级地震。日本海西部发生大深震，可以同日本海沟地震配合，对华北地震趋势作出估计，继台湾东部沿海两次７级地震之后，中国台湾海峡发生一次强震。     

1994年7─9月的全球地震动态

１９９４年第三季度，全球地震活动仍维持中等水平，西南太平洋的瓦努阿图群岛发生７．４级地震。美国加州北部海域发生７．０级地震。日本海西北部发生大深震，可以同日本海沟地震配合，对华北地震趋势作出估计。继台湾东部沿海两次７级地震之后，中国台湾海峡发生一次强震。     

1998年河北省及华北地区地震概况

１１９９８年河北省及京津地区地震活动实况１．１据河北省地震台网测定,１９９８年１月１日至１２月３１日河北省及京津地区共发生地震１７０８次,ＭＬ＜２．０级地震１１９１次,ＭＬ２．０～２．９级地震３６３次,ＭＬ３．０～３．９级地震１２２次,ＭＬ４．０～４...     

1994年8月华北M＿L≥3．0地震动态

１９９４年８月华北Ｍ＿Ｌ≥３．０地震动态１９９４年８月份在华北（３３．０°─４２．０°Ｎ，１１１１．０°─１２５．０°Ｅ）范围内共发生Ｍ＿Ｌ≥３．０地震３次（见下表），无４级以上地震发生。本月华北地震活动水平偏低，三次地震全部发生在华北南部。山西和顺...     

1995—1996年云南孟连西,武定,丽江三次强震前的地震活动背景性异常

分析了１９９５￣１９９６年发生的云南孟连西７．５级、武定以北６．５级和丽江以北７．０级三次强震前云南及邻近地区出现的地震活动背景性异常,包括地震空区、条带、小震群活动、地震窗口、诱发地震、强震原地复发以及迁移等特征。对地震活动期的分析表明,１９８８年澜沧－耿马地震后云南地区处于强震活动高潮期,１９９３年区内发生５．０￣６．３级地震７次,达到发生７级以上强震的预报指标。这些地震活动背景异常为这３次强     

青海共和7.0级地震与龙羊峡水库关系探讨

龙羊峡水库建立于青海省和共盆地内，大坝围堰拦洪期间，于１９８１年１１月２３日在坝址附近发生最大震级Ｍｓ２．３的小震活动当时坝前壅水高度国３９ｍ。１９８６年１１月大坝截流蓄水后约３年半，于１９９０年４月２６日在距库尾约４０ｋｍ处发生Ｍｓ７．０级地震，其后至１９９４年１０月发生Ｍｓ≥５级地震多次，且有震中逐渐靠近水库的趋势，共和７．０级地震引起了地震界是水库地震研究者的广泛关主，我们根据已发表的有关资     

1996年全球地震活动综述

１９９６年全球地震活动已从１９９５年的峰值开始下降。全年共发生６级以上地震１１４次，有４次大地震，震级至少为７．７级左右。最近４年来，全球地震逐渐加强，至１９９５年为一峰值，１９９６年的Ａ（ｂ）值回落，与１９９４年相近。１９９６年，西北太平洋地震带地震相对加强，亚欧带地震则相对减弱，但中国大陆地震活动较１９９５年有所增强。     

大同—阳高6.1级地震活动背景

本文从较大时空范围研究了１９８９年大同－阳高６．１级地震的地震活动性背景，认为大同－阳高地震不是一次孤立的地震事件，是大同盆地历史６级以上地震活动的继续和必然。在时间进程中它们受华北地震区和山西地震带强震活动周期的制约，空间上与北三省交汇区中强地震成丛活动密切相关。大同－阳高６．１级、５．８级地震以及此期间的侯马４．９级、析州５．１级地震是山西地震带中强地震即将活跃的一个迹象，也是华北区域应力场增     

1989年大同—阳高地震前后的地震危险性分析及概率预测

通过对山西境内地震序列的分析计算，得出一个适合山西地区地震活动的概率模型。并以此模型对１９８９年前后的地震活动进行了计算，给出１９８９年以来山西地震频繁活动的理论依据，对今后的地震活动进行了预测。     

山西大同-阳高地震活动背景

通过对大同盆地历史地震活动及大同盆地历史地震活动与华北地震区、山西地震带强震活动的关系的研究，得出山西大同-阳高1989年6．1级地震活动是这一地区历史地震的延续，是华北北部中强地震活动的重要组成部分，具有广义前震的重要意义，其后对应发生的河北张北6．2级地震。标志着华北地震区的地震活动期已进入尾声。     

Magma intrusion as a driving mechanism for the seismic clustering following the 9 May 1989 earthquake swarms at the Canary Islands

On 9 May 1989 a M _L = 5.2 earthquake struck a region between the islands of Tenerife and Gran Canaria. We investigated the time-spatial evolution of seismic patterns affecting the Canary Islands region during 1989–1995, using a quantitative spatial fractal analysis method. This method allows quantitative investigation of subtle trends in seismicity distribution through time. The fractal analysis indicates that epicenters clustered around a large zone during the May 1989 sequence affected narrow zones during 1991–1993, but then larger zones during 1993–1995 with an overall trend to shallower focal depths. The spatial localisation of seismic data and its time evolution appear to be related to magmatic rather than tectonic activity. Spatial clustering properties of seismicity are consistent with a major intrusive episode in 1989, followed by a period of quiescence and renewed deep intrusive activity from 1993 onwards. This interpretation suggests an increasing probability of future volcanic hazard in the region investigated.     

Wavelet-based multifractal analysis of earthquakes temporal distribution in Mammoth Mountain volcano,Mono County,Eastern California

This paper presents a wavelet-based multifractal approach to characterize the statistical properties of temporal distribution of the 1982–2012 seismic activity in Mammoth Mountain volcano. The fractal analysis of time-occurrence series of seismicity has been carried out in relation to seismic swarm in association with magmatic intrusion happening beneath the volcano on 4 May 1989. We used the wavelet transform modulus maxima based multifractal formalism to get the multifractal characteristics of seismicity before, during, and after the unrest. The results revealed that the earthquake sequences across the study area show time-scaling features. It is clearly perceived that the multifractal characteristics are not constant in different periods and there are differences among the seismicity sequences. The attributes of singularity spectrum have been utilized to determine the complexity of seismicity for each period. Findings show that the temporal distribution of earthquakes for swarm period was simpler with respect to pre- and post-swarm periods.     

辽宁岫岩5.4级地震临震预测

简要介绍了1999年11月29日辽宁岫岩Ms5.4地震成功预报的震前主要预测依据及基本思路。通过对震前辽宁地区地震中短期危险性的分析，确定辽南地区是未来主震的危险地区。根据地震活动的区域特性及岫岩偏岭震群活动的规律，判定岫岩震群的前震性质。利用地震活动性参数计算结果和震前在震中及邻近地区出现前兆短临异常的统计分析，进一步论述了震前预测地震三要素的基本依据。     

Discussion on the Relation Between the Probabilistic Distribution of Magnitude in a Seismic Province and That in an Area with Potential Seismic Source

According to the joint probabilistic distribution model of magnitude and space,the author discusses the relationship between the probabilistic distribution of magnitude in a seismic province and that in an area with potential seismic sources.The results show that if the magnitude probabilistic distribution follows the truncated exponential form in a seismic province,there must be some potential source in which the magnitude probabilistic distribution does not conform to that form.The result is consistent with the concept of "characteristic earthquake" derived from the study of actual records of seismicity and the study of geology.The author suggests that the relationship between the probabilistic distribution of magnitude in a seismic province and that in a seismic potential area must be considered in the study of the analysis of seismicity,seismic zonation and engineering seismology,for the purpose of the evaluation of the probabilistic distribution of magnitude correctly in every area with potential s     

华南地区弥散地震活动的评价方法与结果

根据华南地区现今地球动力学环境、新构造特征、发震构造模型、第四纪构造活动、地球物理场等方面的差异,通过具体的实例,有针对性地论述了弥散地震区划分的方法,系统地阐述了华南地区弥散地震的评价依据.对于弥散地震区内与已知发震构造无关的最大历史地震,给出了两种情况下确定弥散地震的方法,探讨了总体地震和构造活动水平与弥散地震的关系.华南地区弥散地震活动的评价结果与地球动力学环境特征密切相关,地震构造背景的一致性是进行弥散地震类比的基础.本文除了论述弥散地震活动评价方法之外,还初步给出了华南地震区弥散地震区划分方案和弥散地震评价结果.     

Machine learning-based automatic construction of earthquake catalog for reservoir areas in multiple river basins of Guizhou province,China

Large reservoirs have the risk of reservoir induced seismicity. Accurately detecting and locating microseismic events are crucial when studying reservoir earthquakes. Automatic earthquake monitoring in reservoir areas is one of the effective measures for earthquake disaster prevention and mitigation. In this study, we first applied the automatic location workflow (named LOC-FLOW) to process 14-day continuous waveform data from several reservoir areas in different river basins of Guizhou province. Compared with the manual seismic catalog, the recall rate of seismic event detection using the workflow was 83.9%. Of the detected earthquakes, 88.9% had an onset time difference below 1 s, 81.8% has a deviation in epicenter location within 5 km, and 77.8% had a focal depth difference of less than 5 km, indicating that the workflow has good generalization capacity in reservoir areas. We further applied the workflow to retrospectively process continuous waveform data recorded from 2020 to the first half of 2021 in reservoir areas in multiple river basins of western Guizhou province and identified five times the number of seismic events obtained through manual processing. Compared with manual processing of seismic catalog, the completeness magnitude had decreased from 1.3 to 0.8, and a b-value of 1.25 was calculated for seismicity in western Guizhou province, consistent with the b-values obtained for the reservoir area in previous studies. Our results show that seismicity levels were relatively low around large reservoirs that were impounded over 15 years ago, and there is no significant correlation between the seismicity in these areas and reservoir impoundment. Seismicity patterns were notably different around two large reservoirs that were only impounded about 12 years ago, which may be explained by differences in reservoir storage capacity, the geologic and tectonic settings, hydrogeological characteristics, and active fault the reservoir areas. Prominent seismicity persisted around two large reservoirs that have been impounded for less than 10 years. These events were clustered and had relatively shallow focal depths. The impoundment of the Jiayan Reservoir had not officially begun during this study period, but earthquake location results suggested a high seismicity level in this reservoir area. Therefore, any seismicity in this reservoir area after the official impoundment deserves special attention.     

福建省龙海—漳浦沿海第四纪地壳运动特征与地震

本文论述了福建龙海—漳浦沿海地区的第四纪地层及沉积结构、构造地貌、第四纪地壳运动特征及其与地震活动的关系。