琼中地震台连续重力变化特征

收集了2009年以来琼中地震台（以下简称琼中台）连续重力观测数据,经对原始数据进行突跳、台阶和删除错误数据等处理,计算分析了琼中台重力潮汐变化数据特征、M₂波潮汐因子变化特征和典型事件的观测数据频谱特征。结果表明,琼中台连续重力观测数据除包含了固体潮、零漂等长周期信号外,也记录到了地震和台风等高频信号。对于记录到的7.0级以上强震,地震信号的频率主要分布于0.3 Hz以内;台风引起的扰动信号则主要分布于0.1—0.4 Hz频带内。同时,2009年以来,琼中台连续重力原始数据及其M₂波潮汐因子无明显前兆异常。      

新疆3次6级强震前的短期前兆异常

分析了新疆3次6级强震前的短期前兆异常动态演化图像特征。这3次地震前兆异常的共性是地震前半年都出现了不同程度的短期前兆异常变化,且在震前2个月,短期异常均超过8项。但是3次6级强震发生前前半年的短期前兆异常变化不一致,有向震中迁移的,有包围震中的,还有前兆异常逐渐减少的。这些前兆异常现象同通常认为的越临近地震前兆异常数目越多是不一致的。     

滇西南地区M≥5级地震活动特征及预报方案

通过对滇西南地区Ｍ≥５级地震前地震、前兆和环境因子变化特征的分析,发现滇西南中强震前小震频度增加、出现窗口信号地震,前兆异常数量多,气压涨落突出等特征,并以此为依据建立了滇西南地区Ｍ≥５级地震的预报方案。     

澜沧地震前昆明弥渡重力场变化特征

本文用澜沧—耿马地震前后昆明台和弥渡台的重力固体潮观测资料对震前昆明、弥渡的重力场进行了潮汐变化和非潮汐变化的分析研究。研究表明澜沧—耿马地震前昆明、弥渡的重力场变化有如下特征:1.重力值变化和重力值差分值变化不明显。2.重力潮汐因子有较明显的负异常变化。3.重力潮汐因子变化的异常时间和1976年5月29日龙陵7.3、7.4级地震异常时间半年多接近;异常的最大变幅处于同一量级,但澜沧地震前昆明台的最大变幅4.7%比龙陵地震前的最大变幅3.4%稍大。4.重力潮汐因子变化有较明显的中期异常,短期异常也有一定反映,但临震异常不明显。     

基于一种新智能优化算法与谱相关方法对重力固体潮的分析

根据月球与太阳相对于地球位置的关系,建立一个三维正交分解模型来揭示重力固体潮中包含的谐波成分。在此基础上,提出一种基于单形邻域与多角色进化策略智能优化算法的独立分量分析方法,用以提高算法效率和全局寻优能力;并结合谱相关方法,对重力固体潮观测数据进行处理和分析,观察其频域和时域的变化。最后引入理论信号和理论计算值作为参考背景,以凸显其异常变化特征。研究表明,利用该方法可以有效地反映出重力固体潮潮汐的日波、半日波、长周期波等特征。同时,发现重力固体潮潮汐的异常变化中隐含有地震前兆信息,通过对云南地区观测数据的分析,在排除测量误差和环境影响外,发现在地震前2~5个月内,重力固体潮的长周期波均呈现出规律性的异常变化。这反映出地震的前兆异常信息,可能对地震时间和地点的预测提供依据。     

2000年9月12日兴海6.6级地震短期预报的总结及反思

通过分析2000年9月12日兴海6.6级地震的震前异常,认为震前异常演化具有明显的阶段性特征,即存在前兆场出现-地震活动场的变化-前兆场的转折变化-地震活动场和前兆场继承性同时变化-宏观(含动物异常)和微观的巨变异常-发生强震的过程。     

24小时拟合检验方法的应用

地震前兆观测中有许多方法都能观测出固体潮汐的变化,如重力、倾斜、应变、地下水位等。固体潮汐的观测资料除用于地球结构、地球物理性能等的研究之外,主要用于地震预报、是地震前兆观测中能够预知其正常背景的手段。知道了正常变化范围,就能区分出异常变化。从中再找出地震前兆的异常变化。 固体潮观测的各手段进行地震预报时,普遍应用潮波的观测振幅与理论振幅的比值的变化和漂移     

滇西地区强震与地形变异常的前兆特征

以形变(倾斜、应变)观测资料,采用经过实效检验分析后有效率较高的形变前兆参量及异常判别方法,以近年来发生在滇西地区的6级以上地震：武定地震、丽江地震、宁蒗地震以及姚安地震的震例,用滇西及川滇交界地区形变观测网的资料进行综合分析,重点对该地区强震前兆异常的时空演化及特征进行分析研究,对其在强震前中短阶段的前兆异常变化的基本特征进行了探讨。     

西北地区6级以上强震的断层气体前兆异常特征研究

本文在对西北地区６级以上地震进行深入研究的基础上，通过５级左右地震相对比的方式，对６级以上强震的断层气体前兆的时、空、强异常变化；阶段性变化；异常时间与震中距的对应；异常相对集中和短临信息等五个方面的特征进行了总结，该研究未来强震前兆的识别和分析有一定的实用价值。     

值得探讨的“长趋势异常”

本文根据兰州地震研究所王长岭等同志的文章中提到的在1976年松潘7.2级地震前松潘川主寺水氡和1981年道孚6.9级地震前姑咱水氡均有几年的趋势性升高异常的情况,进行了初步研究,又对四川省水氡、地磁、地电、地倾斜、磁偏角、重力和短水准测量等7种前兆手段从1970—1980年的年平均值资料进行分析后,发现前兆资料的多手段、多台点、大范围和长时间出现的上升(或下降)变化与强震的形成和发生似乎无明显关系,而在长期上升(或下降)背景上出现的变化,作为畸变,才可能与强震有关。文中还对引起前兆资料的长期规律变化的原因,作了初步的探讨。     

CHARACTERISTICS OF MULTI-SCALE GRAVITY FIELD VARIATION AND SEISMOGENIC MECHANISM ANALYSIS IN THE SOUTHEASTERN TIBETAN PLATEAU

As the most basic geophysical field, the earth gravity field has achieved wide attention, and its spatial anomaly characteristics and dynamic variation can provide important scientific basis for studying the internal structure and dynamics of the Earth. Based on the mobile gravity observation data of the southeastern Tibetan plateau from 2013 to 2016, the dynamic variation tendency and anomaly characteristics of the regional gravity field in different temporal resolutions are obtained before and after the Ludian and Jinggu earthquakes in the study area respectively. The method of wavelet multi-scale decomposition is used to analyze the relationships of gravity field variation with the earth movement, material density change, and strong earthquake preparation. The deep material variation, dynamic process and the mechanism of earthquake inoculation in the southeastern Tibetan plateau are further discussed. Results indicate that the gravity field variation in the source region before the Ludian and Jinggu earthquake respectively is characterized by obvious positive and negative anomalous transition zone and gradient zone that are consistent with the direction of fault tectonics, suggesting the strong crustal movement and mass migration during the earthquake incubation period. The result of wavelet multi-scale decomposition of the gravity field during the period from September 2013 to April 2014 shows that the gravity field variation at different depth and space scale in the crust and upper mantle of the southeastern Tibetan plateau is significantly correlated with seismic distribution and the location of active fault zone. This indicates that the earthquake inoculation in the study area is closely related to the fault movement and the distribution of material density in the crust and upper mantle, which may be affected by the complex deep dynamic process of the material migration in the crust and mantle. The characteristic that strong earthquakes always occur near positive and negative anomaly transition zones and gradient zones of gravity field change is preliminarily explained, based on the dynamic process of material migration in the crust and upper mantle of the southeastern Tibetan plateau. The research results of this paper have some reference value to the study on the earth movement and seismogenic mechanism.     

地震前地表重力场变化的一种可能解释——应力-损伤耦合效应

文中运用损伤力学研究方法 ,提出孕震过程中引起地壳破坏的应力 -损伤耦合效应。利用应变等效性假设 ,推导了地壳体的应力 -损伤耦合效应与地表重力变化之间的理论关系。根据岩石力学实验的不同加载途径 ,模拟了 1976年唐山 7 8级地震和 2 0 0 1年昆仑山口西 8 1级地震重力演化的不同特征 ,结果与实际情况符合较好 ,表明应力 -损伤耦合效应可以作为地震前地壳重力变化的一种物理解释     

STUDY ON DYNAMIC CHANGE OF GRAVITY FIELD IN XIANSHUIHE FAULT ZONE AND THEIR RELATION TO THE OCCURRENCE OF MS ≥ 5.0 EARTHQUAKES

Xianshuihe Fault, a main strong earthquake activity belt in southwest China, begins from Ganzi in the northwest, passes through Luhuo, Daofu, and Kangding, and then extents along the Dadu River valley. The fault is divided into two parts at Shimian, one part turns to south and converses to Anninghe Fault extending further to south, the other part, continuing to extend to southeast, cutting through Xiaoxiangling and then changing to Daliangshan Faults in the north of the Yuexi Basin, has the length of about 400km. Since 1700AD, there have happened 22 earthquakes larger than magnitude 6.0 and 8 earthquakes larger than magnitude 7.0. In this paper, we systematically collated and computed the gravity repetition measurement data along the Xianshuihe fault zone since 1988, and by referring to the anomaly index of gravity field of the predecessor achievements, analyzed the spatial-temporal variation of the regional gravity field and the relation to the occurrence of ≥ M_S5.0 earthquakes. The mechanism of the regional gravity changes is further studied, and also the implication of strong earthquake risk because of the dynamic variation of gravity field in the near future is discussed.The results show that:1)The mobile gravity observation has the ability to detect crustal activity and M_S ≥ 5.0 earthquake events. 2)There is definite correspondence between interannual gravitational field change and the 8 earthquakes among the 13 M_S ≥ 5.0 earthquakes occurring in the surveying area since 1988, which can be determined according to the change of interannual gravitational field. Three M ≥ 6.0 earthquakes occurred 3~4 years after the abnormal image was developed, 4 earthquakes that occurred in the region of no data available were not determined. 3)A significant feature of the spatial-temporal variation of the regional gravity is a north-south run-through image before 2004, and characterized by the alternatively positive or negative variation in different year, the earthquakes of M_S ≥ 5.0 occurring in this period were not distributed along the fault. Gravity variation magnitude indicates that there were two similar crustal material movement waves before 2004, corresponding to the course of earthquake space-time distribution from strong to weak in the study area. After 2010, the variation image shows that the local positive and negative zones are concurrent within a year, different from the image before 2004, and earthquakes of M_S ≥ 5.0 basically occurred on the fault. It is believed that the variation of gravity field since 1988 and the seismic distribution fit with the geodynamic mode of strong and weak stages of the northeast motion of Indian plate. According to the conclusion we can try to optimize gravity anomaly index. After the Kangding earthquake in 2014, the north segment of Moxi Fault was still subject to negative high value changes till 2017 and then the gravity variation was further developed to a four quadrant distribution image. Based on the analysis of this paper and the previous variation trend of gravity field, we believe that the north segment of Moxi Fault has the background of medium-long term, strong or large earthquake risk.     

冀鲁豫交界地区重力场变化与区内小震关系探讨

冀鲁豫交界地区历史上曾发生过多次中强地震,是一直受关注的地震危险区。利用该区1995—2010年共20期的流动重力观测资料,在统一起算基准、消除系统误差的基础上进行拟稳平差,计算重力场累积变化量;通过对重力场变化的分析,研究测区内重力场动态变化与测区内发生的一系列4级左右地震的关系。研究结果认为:冀鲁豫地区发生M_L4.0以上地震前后震区的重力场变化具有明显的"震前持续上升-震后反向恢复"的特征。     

郫县重力异常与四川近年地震关系的震例分析

本文介绍了容量限制分配方法的概念、交通量与车速的特点、容量限制分配方法的具体应用步骤和分配次数对分配结果的影响等。     

中国大陆西部重力场变化与强震危险性关系

本文基于中国大陆西部流动重力测量获得的区域重力场变化数据, 尝试对其进行多种位场变换, 在一定空间尺度约束下定义了6种区域重力场变化指标量. 在此基础上, 以中国大陆2002年、 2005年和2008年等3期数据为研究对象, 计算并统计了中国大陆西部M_S≥6.0地震震中位置处震前重力场变化及各种导出参数值, 尝试初步构建以地震预报为目的的地震重力学科指标体系参数. 研究结果表明, 震前区域重力场变化与地震发生位置没有显著的统计关系, 但是重力场变化的垂直梯度和解析信号模量具有一定的地震预报意义, 适合作为地震前兆异常使用.      

鲜水河断裂带重力场随时间的变化及其与地震之间的联系

处理鲜水河断裂带上１９８７年至１９９５年间的八期高精度重力复测资料，并利用计算机辅助图形分析程序将所有相邻两期的重力变化速度值转换为速率等值线图，通过对资料的逐一分析及与地震对应关系的比较，我们看到，鲜水河断裂的重力变化与其我及的地震之间有一定的联系。存在震前重力发生较大异常变化，震后重力立即发生反向直至恢复的变化，并且震前的重力异常变化量     

华北地区重力场变化特征研究

通过对1992~2008年间各期观测资料进行全时空扫描,分析华北地区网区重力场的演化特征,总结震前异常的形态、持续时间和变化幅度,指出重力场空间变化易于发生地震的部位,并对一些问题进行讨论。结果显示:华北地区重力场总体变化不具明确规律性;大量测点存在明显的背景性趋势性异常变化;重力场变化与网区及周边地区中强地震的活动联系密切,较明显的重力场异常反应多发生在震前2年左右时间,且常伴有大面积高值异常区出现。重力变化"0"线、高梯度带、异常中心(含极值)附近是重力场空间变化易于发震的部位。     

陕西地区流动重力历史资料清理分析

介绍流动重力历史资料清理流程、方法及获得的规范化成果,对1998年泾阳MS 4．8、2009年高陵MS 4．4地震前后的重力场变化进行分析,得到结论：①泾阳地震前后重力场变化满足“震前重力持续增强-震后反向恢复”的特征;②泾阳地震的发生可能与附近断裂活动有关,同时受华北块体应力场的作用;③高陵地震前后重力变化与泾阳地震前后重力变化具有一定的相似性,且位于渭河断裂附近,两个地震均受到渭河断裂活动的影响。