板内与板间地震活动时空分布的多重分形特征研究

利用多重分形分析方法，考察了中国大陆和台湾地区以及新西兰的地震活动广义应变释放时间和空间分布的多重分形特征. 结果表明，地震活动时空分布的多重分形特征与不同地球动力学环境关系密切. 强震活动时间分布在板间地区具有比板内地区更明显的丛集性， 对中小地震这种丛集性差异较小；强震活动空间分布在板内地区具有比板间地区更强的丛集性，但对中小地震则相反.      

板内大震原地准周期复发间隔的概率分布

以中国大陆大震原地复发资料为基础,采用比较合理的方法确定了板内大震在其活跃期内原地准确周期复发的概率密度函数,所得结果表明,板内大震在重复行为上具有板间特征地震相类似的分布特征,两者的差异在于,板内大震复发间隔的变分系数ＣＯＶ为０．２６,而板间特征地震的该值为０．２１５,即板内大震的重复间隔相对稍显离散。     

东亚及西太平洋地区的地震系列

东亚及西太平洋地区的强震与中强震系列可以分类为板间地震系列与板内地震系列。本文研究了它们各自的特征、公式及其相互关系。如果把本区作为一个自动调节与相对平衡系统来考虑，可以较满意地说明上述结果。如果此看法能成立，使用地震系列准确地预测强震将有广阔的前景，并为地震预测提供一个现实的、可行的、较准确的预测方法。     

Sources of Tsunami and Tsunamigenic Earthquakes in Subduction Zones

—We classified tsunamigenic earthquakes in subduction zones into three types earth quakes at the plate interface (typical interplate events), earthquakes at the outer rise, within the subducting slab or overlying crust (intraplate events), and "tsunami earthquakes" that generate considerably larger tsunamis than expected from seismic waves. The depth range of a typical interplate earthquake source is 10–40km, controlled by temperature and other geological parameters. The slip distribution varies both with depth and along-strike. Recent examples show very different temporal change of slip distribution in the Aleutians and the Japan trench. The tsunamigenic coseismic slip of the 1957 Aleutian earthquake was concentrated on an asperity located in the western half of an aftershock zone 1200km long. This asperity ruptured again in the 1986 Andreanof Islands and 1996 Delarof Islands earthquakes. By contrast, the source of the 1994 Sanriku-oki earthquake corresponds to the low slip region of the previous interplate event, the 1968 Tokachi-oki earthquake. Tsunamis from intraplate earthquakes within the subducting slab can be at least as large as those from interplate earthquakes; tsunami hazard assessments must include such events. Similarity in macroseismic data from two southern Kuril earthquakes illustrates difficulty in distinguishing interplate and slab events on the basis of historical data such as felt reports and tsunami heights. Most moment release of tsunami earthquakes occurs in a narrow region near the trench, and the concentrated slip is responsible for the large tsunami. Numerical modeling of the 1996 Peru earthquake confirms this model, which has been proposed for other tsunami earthquakes, including 1896 Sanriku, 1946 Aleutian and 1992 Nicaragua.     

濮阳小震集中区地震丛集特征分析

利用濮阳小震集中区1970年1月—2019年12月地震目录,基于最邻近事件距离算法计算地震丛集率,分析该区地震丛集特征。结果发现:(1)在中强地震前,濮阳小震集中区地震丛集率存在高值现象,而后出现不同程度的低值,与强震前地震活动从增强到平静的过程相吻合,对地震危险区判定有一定指示意义;(2) 1997年以来,4级以上地震主要分布在聊城—兰考断裂西侧,且小震出现相对“稀疏”异常,应给予关注。     

Multifractal Approach to Time Clustering of Earthquakes. Application to Mt. Vesuvio Seismicity

—The clustering structure of the Vesuvian earthquakes occurring is investigated by means of statistical tools: the inter-event time distribution, the running mean and the multifractal analysis. The first cannot clearly distinguish between a Poissonian process and a clustered one due to the difficulties of clearly distinguishing between an exponential distribution and a power law one. The running mean test reveals the clustering of the earthquakes, but looses information about the structure of the distribution at global scales. The multifractal approach can enlighten the clustering at small scales, while the global behaviour remains Poissonian. Subsequently the clustering of the events is interpreted in terms of diffusive processes of the stress in the earth crust.     

中国强震的丛集性特征及其意义

本文提出了利用地震平均重现周期判别地震丛集和确定地震丛集等级的方法。进而研究了中国M_s≥7.0地震的丛集事件分布特征,得到丛集事件等级一频次分布式和时间分布式。在此基础上,本文对中国大陆强震丛集事件作了背景预测。结果认为:中国大陆自1988年11月起,在未来15年内,发生强震丛集事件的概率为83.3％,其最大可能的等级为D_T=Ⅲ级。     

山西洪洞、临汾历史大震区现今地震的重新定位

利用临汾地区无线传输地震台网资料，对1303年洪洞（M＝8）、1695年临汾（M＝73／4）两次特大地震所在区域1987年－1999年发生的1670次中、小地震进行了重新定位。结果表明，重新定位后震源深度的测定情况比原有结果有很大改善，定位精度明显提高。两次历史大震所在区域中现今地震的密集区，与两次大震各自的高烈度区长轴方向、形状和大小相吻合，反映了历史大震震源断层对现今小震活动的约束作用。小震震源深度的分布情况表明，两次历史大震的震源断层可能都比较浅。重新定位结果为利用现今小震的群体特征研究历史大震的震源断层提供了良好的基础资料。     

An overview on the seismicity of Cuba

The seismicity of Cuba is briefly presented together with a few fundamental neotectonic elements of the adjacent Caribbean region. The Cuban seismicity catalogue has been extended back to 1528 and it shows that the largest earthquakes occurred in 1766 and 1852 (I = IX MSK). Two types of seismicity (intraplate and interplate) can be distinguished in Cuba. Western and Eastern Seismotectonic Units correspond to intraplate type and the Southeastern Seismotectonic Unit to interplate type. Western Cuba is characterized by a low frequency of earthquake occurrence. Distribution of epicenters is not regular and the most important events mainly concentrate along two regional active fault system (Nortecubana and Surcubana). Due to the lack of seismic stations in this region, the characterization of seismicity is frequently done on the grounds of historical data available from 1693. The main seismogenic source for Cuba is the Bartlett-Cayman fault system, but inland there are other active structures. Some issues about historical and present day Cuban seismological research are also showed.     

云南地区地震活动的有序迁移图像

重点追踪了云南地区中强震的动态图像 ,发现在云南地区强震活跃期前 1～ 4a出现中强震的有序迁移 ,有序迁移的中强震预示了活跃期强震时空分布的总体格局 ,80 %的强震发生在这些中强震 15 0km范围内。有序迁移结束后 2d至 11个月发生活跃期的首次强震 ,其中 75 %在 3个月内。文中介绍了强震的等间距迁移、强震活跃期后期中强震的有序迁移 ,巨震前后大震的有序迁移和中等地震的定向迁移与部分震例 ,但地震活动有序迁移图像的机理尚待研究     

中南美洲地区地震序列的特征

共搜集到１９６０￣１９９０年中、南美洲地区１０个地震序列。其中１个是板内地震序列。这个板内地震序列表现出的特征是：震中分布区域的长轴较短,长短轴之比低;余震震源机制和主震震源机制相比变化大。其余９个是俯冲带上的板缘地震序列,它们的共同特征是：震中分布区域的长轴较长;震源深度下限超过地壳,可以达到７０ｋｍ以下（第１０号序列例外）;主震的震源机制受俯站带的走向、倾向和倾角的控制。但是这些震序列又分为两     

汶川8.0级地震后中国大陆强震活动状态研究

本文从不同空间、 时间尺度对2008年四川汶川8.0级地震的影响意义进行了初步讨论, 并以此分析了其后我国大陆的强震活动状态。研究结果表明, 1800年以来中国大陆西部及邻区的大三角地区8级地震活动呈现为100年左右丛集性时间过程, 具有地震平静、 地震丛集、 地震丛集发生前的过渡和丛集发生后的调整等时间特征; 2001年11月14日昆仑山口西8.1级地震和2008年5月12日四川汶川8.0级地震的发生表明, 目前该地区可能处于8级地震丛集发生前的过渡时段。20世纪以来, 中国大陆7级强震的时间活动过程明显受大三角地区8级地震时间进程的影响, 在8级地震活动的1900—1955年时段内, 7级地震幕式活动划分不显著, 而在8级地震平静的1956—2000年时段内, 7级地震幕式活动划分清晰; 以2008年汶川8.0级地震为标志, 受大三角地区8级左右巨大地震活跃控制, 中国大陆可能将进入一组新的幕式活动不清晰的、 类似于1900—1955年的强震活跃时段。     

最大熵原理在地震时间间隔和震级分布中的应用

基于最大熵原理,得到地震时间间隔和地震震级的概率分布函数。根据时间间隔分布,得到地震发震概率,当概率上升达到警界值时,可对云南5级以上中强地震做出预测。6个月以内中短期预测对应率为91％;3个月以内,短临期预测对应率为73％。根据震级分布,得到用最大熵原理求出的地震理论发生次数,理论发震次数与实际较为接近。用最大熵原理求出了云南不同地区不同震级档次5级以上中强地震的复发周期。分析认为,云南7级以上大震危险性在逐步逼近,西部危险性高于东部。     

Paleotectonic structures and their influence on recent seismo-tectonics in the south Kuril subduction zone

Abstract Bathymetric data from south of Hokkaido obtained during a cruise of R/V Hakuho-Maru are summarized, and their correlation with earthquake occurrence is discussed. There are structural lineations on the seaward slope of the Kuril Trench, oblique to the Kuril Trench axis and parallel to the magnetic lineations in the Pacific plate. The structural lineations comprise horst-grabens generated by normal faulting. This suggests that Cretaceous tectonic structures originating at the spreading centre affect present seismotectonics around the trench axis. The structural-magnetic relation is compared to the case of the Japan Trench. North-east of the surveyed area, there are two major fracture zones (Nosappu Fracture Zone and Iturup Fracture Zone) that divide the oceanic plate into three segments. If the fracture zones (FZ) and the zone of paleo-mechanical weakness, represented by magnetic lineations, can control the direction of normal faults at a trench, the extent of the resulting topographic roughness on the seaward slope of the trench would be different across an FZ because of the differences in ages. By studying recent large earthquakes occurring in the south Kuril region, it is shown that several main-aftershock distributions for large earthquakes in this region are bounded by the Nosappu FZ and the Iturup FZ. Two models (Barrier model and Rebound model) are presented to interpret earthquake occurrence near the south Kuril Islands. The Barrier model explains seismic boundaries seen in several examples for earthquake occurrence in the south Kuril regions. The fracture zone forming the boundary of two segments with different magnetic lineations is also the boundary of two different normal fault systems on their ocean bottom, and the difference in sea-bottom roughness between two normal fault systems should affect the seismic coupling at a plate interface. Due to the difference of seismic coupling, earthquake occurrence is controlled by an FZ and then the FZ acts as a seismic boundary (Barrier model). Existing normal faults created by plate bending of subducting oceanic plate should rebound after its subduction (Rebound model). This rebound of normal faults may cause intraplate earthquakes with a high-angle reverse-fault mechanism such as the 1994 Shikotan Earthquake. The energy released by an intraplate earthquake generated by normal-fault rebounding is not directly related to that of interplate earthquakes such as low-angle thrust earthquakes. It is a reason why large earthquakes occurred in the same region during a relatively short period.     

云南地区中强地震震源破裂图像

利用等震线和余震序列资料,主要研究了云南地区１５１次中、强震的震源破裂方向资料,给出云南地区中强地震震源破裂的空间展布图像。结果表明,该区的５～６级地震破裂相对较散乱,没有明显的优势方向。而７级以上地震破裂具有明显的方向性,以北北西－北西向为主,占６３％;其次是近南北向,占２１％它们形成了３条具相当规模的震源破裂带。     

新西兰地区地震活动时空分布的多重分形特征研究

利用多重分形维数谱估计的Hill方法，讨论了新西兰地震活动区地震活动的震源分布、震中分布以及时间间隔分布的多重分形特征．结果表明，该地区浅源地震的震中分布和震源分布在给定不同的起始震级的条件下均具有明显的丛集特征；对于中、深源地震这种特征不甚明显．而地震活动时间间隔分布则无论对于浅源和中、深源地震均呈单重分形的性质，但具有分形性质的尺度范围有较大的差别．这些结果表明，浅源地震与中、深源地震的活动特征显著不同．      

甘肃省若干地段强震地面运动特征

以甘肃、陕西等地历年来获得的强震记录,主要是汶川大震的强震记录,研究了甘肃省强震地面运动的特征以及不同场地的地震反应。注意到本地地震动具有大陆板内地震的特点,与强震记录最多的美国西部地震动有较大的差别。甘肃的场地类型大致可以分为四个区域:河西走廊、黄土地区、陇南山区和甘南高原区,强震地面运动特征各自具有其自身的特点,又和地震动的特性有密切的关系。认为有必要对汶川大震的强震记录作全面而系统的研究,进而应用到我国的地震安全性评价中去。     

Fractal analysis of earthquake swarms of Vogtland/NW-Bohemia intraplate seismicity

The special type of intraplate microseismicity with swarm-like occurrence of earthquakes within the Vogtland/NW-Bohemian Region is analysed to reveal the nature and the origin of the seismogenic regime. The long-term data set of continuous seismic monitoring since 1962, including more than 26000 events within a range of about 5 units of local magnitude, provides an unique database for statistical investigations. Most earthquakes occur in narrow hypocentral volumes (clusters) within the lower part of the upper crust, but also single event occurrence outside of spatial clusters is observed. Temporal distribution of events is concentrated in clusters (swarms), which last some days until few month in dependence of intensity. Since 1962 three strong swarms occurred (1962, 1985/86, 2000), including two seismic cycles. Spatial clusters are distributed along a fault system of regional extension (Leipzig-Regensburger Störung), which is supposed to act as the joint tectonic fracture zone for the whole seismogenic region. Seismicity is analysed by fractal analysis, suggesting a unifractal behaviour of seismicity and uniform character of seismotectonic regime for the whole region. A tendency of decreasing fractal dimension values is observed for temporal distribution of earthquakes, indicating an increasing degree of temporal clustering from swarm to swarm. Following the idea of earthquake triggering by magma intrusions and related fluid and gas release into the tectonically pre-stressed parts of the crust, a steady increased intensity of intrusion and/or fluid and gas release might account for that observation. Additionally, seismic parameters for Vogtland/NW-Bohemia intraplate seismicity are compared with an adequate data set of mining-induced seismicity in a nearby mine of Lubin/Poland and with synthetic data sets to evaluate parameter estimation. Due to different seismogenic regime of tectonic and induced seismicity, significant differences between b-values and temporal dimension values are observed. Most significant for intraplate seismicity are relatively low fractal dimension values for temporal distribution. That observation reflects the strong degree of temporal earthquake clustering, which might explain the episodic character of earthquake swarms and support the idea of push-like triggering of earthquake avalanches by intruding magma.     

汶川Mw7.9和集集Mw7.6地震前应力场转换现象及其可能的前兆意义

2008年四川汶川Mw7.9地震和1999年台湾集集Mw7.6地震均为挤压推覆构造环境下发生的板内逆断层型地震.通过对比分析2次地震前的CMT解、震源区附近的中小地震震源机制解及其反演的应力场可知,集集地震主震震源机制解与用台湾内陆中西部的CMT解反演得到的逆断层类型构造应力场吻合,而在主震前震源区附近中小地震震源机制...     

试论小区地震活动的时间规律

为了探讨小区域内地震活动的时间规律。本文在中国大陆选择了11个地点分析其从远古至公元1990年间的破坏性地震（M≥4 3／4）的活动性。因而发现小区的地震活动规律主要表现于以大震为代表的地震活动分期上，破坏性地震的频率、集中程度与阶段性变化上，以及与所在地震区地震活动期的关系上，不同小区的地震活动特征有共性，有类型区别，更有各自的特殊性。