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1.
大量观测事实表明 ,赋存于地壳深部的流体 (水、气、油 )作为弹性介质 ,对深层地壳应力的分布、变化、转移过程及地震孕育、发生等有着较为灵敏的反映。地震的形成与区域构造应力活动强度密切相关 ,这种大范围的区域应力作用会形成多个应力集中点 ,在众多应力集中点上可产生地下流体前兆异常变化。在对新疆地下流体数十年的监测中 ,发现强震前出现大量与地震有关的由区域构造应力活动引起的前兆异常 ,异常范围广且种类繁多 ,它们在成因、特征上与震源应力活动的前兆异常明显不同 ;这种地下水位地震前兆异常场 ,不能完全孤立地与单个地震事件相对应 ,应充分考虑到它与一组或系列地震有关 ,而这些地震往往与块体挤压、断裂活动等区域性的应力活动有关。因此 ,正确区分并掌握其不同的特性 ,对地震预报具有一定的意义 相似文献
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区分"源兆"与"场兆",系地震预测探索中的重要课题。根据云南4组6级以上地震的地下流体前兆异常资料,系统分析了强震源兆的流体前兆异常特征。结果表明,在6级多强震的源兆区,即震中距100 km范围内,异常项目计有水位、水温、水氡、水汞及气汞;以中期、短期异常为主,临震异常很少;源兆异常台站和台项的比例均高于场兆。这些流体源兆特征的认识,可为利用流体异常判断地震危险区提供一定依据。 相似文献
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利用“专家系统”的思想对每一地震前兆异常事件进行了综合评估，以每一异常的最可能发震时间计算发震概率，利用各类地震前兆异常群体信息熵研究了系统熵值与地震场，源兆的关系，分析了１９７６年唐山７．８级地震前各类地震前兆异常的时空分布特征，然后以唐山为中心在空间上划分三个区，近区，中间区和远区，分别计算了三个区各类地震前兆异常信息熵的时间演化值，分析了震前这种信息熵的场，源兆特征，震中近区的信息熵值要比中 相似文献
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山西大同—阳高6．1级地震形变异常的再研究 总被引：3，自引：1，他引：3
在对山西大同－阳高1989年6．1地震的震例总结中，共收集了23项形变异常，经过对资料的整理研究，又发现了13项。经过进一步总结形变异常的演化特征及物理机制，表明形变异常在震前具有多样性，震源区出现了闭锁现象。中期趋势异常主要受区域应力场的控制，短临异常反映了震源应力场的变化，异常的空间分布是震源应力场和区域应力场相互作用的结果。 相似文献
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IntroductionOn11f50,January10of1998,anMs=6.2earthquakeoccurredattheconjunctionareaofZhangbeiandShangyiCounties,HebeiProvince.TheeaFthquakewasoneofthreemajorstrongearthquakesatthenorthernpartofNorthChinaaftertheMS=7.8earthquakeofTangshan,HebeiProvinceinJuly,1976.Thestrongearthquake,whichoccurredwithintheearthquakeriskareaofconjunctionregionofnorthernBeding-Shanxi,Hebeiandinner-Mongoliathatwasdeterminedastheannuallykeymonitoringareaformanyyears,wasfairlywellforecastedbythemiddle-longandm… 相似文献
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德令哈6．6级地震前青海省前兆异常特征分析 总被引：1，自引：1，他引：0
对德令哈6．6级地震前后前兆异常用常规分析方法和部分“十五”项目的阶段性成果进行分析研究,总结了此次地震前出现的前兆异常形态及特征,探讨了此次地震与昆仑山口西8．1级地震的关系。认为,在8．1级地震的影响下,外围区域应力场调整,地壳介质变化,是此次地震前地下流体出现异常较多、分布广泛的内在原因。 相似文献
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2009年新疆柯坪块体3次5级地震前异常分析 总被引：1，自引：0，他引：1
研究2009年柯坪块体3次5级地震前的地震活动和前兆观测结果表明:3次5级地震前,柯坪块体存在5级地震平静的长期异常,4级地震多次平静、增强交替活动的中期异常,小震集中活动的短期异常;地震发生的短临阶段,震中附近的阿合奇地震台地倾斜、乌什地震台水管倾斜仪及地磁、地电和巴楚地应力存在不同程度的短临异常。参考汶川地震,有关专家对地震预报和震前异常的新思考和新认识,结合3次5级地震的类型和错断方式,分析震前小震活动和前兆异常,并对震前地震活动和前兆异常进行了综合分析和探讨。 相似文献
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华北北部地区3次强震前地下流体异常场及其形成与演化机理 总被引：14，自引：4，他引：10
通过系统地收集与整理１９８９年１０月１９日大同－阳高Ｍｓ６．１、１９９６年５月３日包头西Ｍｓ６．４与１９９８年１月１０日张北－尚义Ｍｓ６．２地震前地下流体异常资料,对比与综合分析了异常的形态特征、空间展布特征、时间变化特征与时空演化特征,进而提出华北北部地区地下流体中短期异常场的形成与演化机理。研究结果表明,中期异常场是区域构造活动的强化产生了地下流体的短期异常场,震源体发展到临震阶段时在震中区生 相似文献
10.
The tropical Pacific experienced a sustained warm sea surface condition that started in 2014 and a very strong El Nio event in 2015. One striking feature of this event was the horseshoe-like pattern of positive subsurface thermal anomalies that was sustained in the western-central equatorial Pacific throughout 2014–2015. Observational data and an intermediate ocean model are used to describe the sea surface temperature(SST) evolution during 2014–2015. Emphasis is placed on the processes involved in the 2015 El Nio event and their relationships with SST anomalies, including remote effects associated with the propagation and reflection of oceanic equatorial waves(as indicated in sea level(SL) signals) at the boundaries and local effects of the positive subsurface thermal anomalies. It is demonstrated that the positive subsurface thermal anomaly pattern that was sustained throughout 2014–2015 played an important role in maintaining warm SST anomalies in the equatorial Pacific. Further analyses of the SST budget revealed the dominant processes contributing to SST anomalies during 2014–2015. These analyses provide an improved understanding of the extent to which processes associated with the 2015 El Nio event are consistent with current El Nio and Southern Oscillation theories. 相似文献
11.
北部湾6.1,6.2级地震的前兆异常 总被引：1，自引：0，他引：1
通过对北部湾６．１，６．１级地震前的震兆分析，认为地震是在区域地震活动出现中期异常背景的情况下发生的，前兆观测的趋势异常较为突出，但短临异常极少，地震活动性和前兆观测手段的趋势异常变化具有稳定性和准同步性，反映了震前区域应力场的变化。 相似文献
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１９８８至１９９０年，青海地区发生了４次震级大于６．０的强震。利用ＧＤＳＮ宽频带波形资料，通过波形模拟，结合地质构造的背景资料对这几次地震进行了震源破裂和发震构造背景的研究。使用台站的准震源时间函数和准时间差的分析方法，对震源和复杂性进行了讨论。 相似文献
13.
A STUDY ON THE ALGORITHM FOR EXTRACTING EARTHQUAKE THERMAL INFRARED ANOMALIES BASED ON THE YEARLY TREND OF LST 
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下载免费PDF全文 SONG Dong-mei ZANG Lin SHAN Xin-jian YUAN Yuan CUI Jian-yong SHAO Hong-mei SHEN Chen SHI Hong-tao 《地震地质》2016,38(3):680-695
There are thermal infrared anomalies(TIA)before earthquake, and TIA has become one of the important parameters for assessing regional earthquake risk. However, not all of the surface infrared anomalies are related to tectonic activities or earthquakes. How to eliminate the influence of non-structural factors and extract the weak signals from strong disturbances is the key and difficult point for tectonic activities studies based on the thermal infrared remote sensing techniques. Land surface temperature(LST)background field is the basis for thermal infrared anomalies extraction. However, the established background fields in previous researches cannot eliminate the influence of climate changes, so the accuracy of thermal anomaly extraction is limited. Now an improved method is proposed. Combined with the periodic character of LST time series, harmonic analysis is lead into the process of LST background field establishment. Specifically, the yearly trend of LST is fitted based on Fourier Approximation method. As a new background field, the yearly trend is dynamic, includes the local and the yearly information. Then, based on the rule of "kσ", the earthquake anomalies, calculated by RST with the yearly trend of LST, can be extracted. At last, the effectiveness of the algorithm can be tested by the quantitative analysis of anomalies with anomaly area statistics, anomaly intensity statistics and distance index statistics. The Wenchuan earthquake was discussed again based on the proposed algorithm with MODIS land temperature products in 2008. The results show that, there were obvious pre-earthquake thermal anomalies along the Longmen Mountains faults with a longer time; but there were no anomalies when the earthquake happened; and the post-earthquake thermal anomalies occurred with much smaller amplitudes and scopes. Compared with the results derived from the traditional RST which is based on the spatial average of LST values, the TIA extracted by the new RST, which is based on the yearly trend of LST, is more fit with the active faults, and the process of the anomalies occurring and removing can be described in more detail. Therefore, as the background field to extract earthquake anomalies, the yearly trend of LST is more reliable. 相似文献
14.
Internal structure of Ustica volcanic complex (Italy) based on a 3D inversion of magnetic data 总被引：1，自引：0，他引：1
A ground magnetic study of Ustica Island was performed to provide new insights into subsurface tectonic and volcanic structures.
The total-intensity anomaly field, obtained after a data-reduction procedure, shows the presence of a W–E-striking magnetic
anomaly in the middle of the island and another two intense anomalies, which seem to continue offshore, in the southwestern
and the northeastern sides, respectively. The detected anomalies were analyzed by a quadratic programming (QP) algorithm to
obtain a 3D subsurface magnetization distribution. The volcano magnetization model reveals the presence of intensely magnetized
volumes, interpreted as the feeding systems of the main eruptive centers of the island, which roughly follow the trend of
the main regional structural lineaments. These findings highlight how regional tectonics has strongly affected the structural
and magmatic evolution of the Ustica volcanic complex producing preferential ways for magma ascent. 相似文献
15.
Ultra low frequeney electromagnetic wave anomaly and its spectrum characteristics before earthquakes
ＵｌｔｒａｌｏｗｆｒｅｑｕｅｎｅｙｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｗａｖｅａｎｏｍａｌｙａｎｄｉｔｓｓｐｅｃｔｒｕｍｃｈａｒａｃｔｅｒｉｓｔｉｃｓｂｅｆｏｒｅｅａｒｔｈｑｕａｋｅｓＪｉａｎ－ＧｕｏＨＡＯ；Ｙｕｎ－ＦｕＺＨＡＮＧ；Ｈｕａｉ－ＷｅｎＰＡＮ；... 相似文献
16.
基于全球EGM2008自由空气重力异常模型,本文计算了蒙古及周边地区的布格重力异常和AiryHeiskanen均衡重力异常.在此基础上,本文采用Crust 1.0地壳模型为参考,通过重力正演方法,对蒙古及周边地区不同深度地壳密度结构模型的重力异常进行了计算,并对得到的正演布格重力异常与实际重力异常进行了对比和分析.研究结果表明:蒙古西部杭爱山地区与阿尔泰山地区的构造变形差异性明显,现今均衡重力异常中杭爱山周边没有明显的均衡异常高值区,而阿尔泰山地区西南方向存在均衡重力异常高值分布,分析与新构造运动密切相关;Crust 1.0模型给出的壳幔横向密度不均匀体分布对于计算Moho面起伏引起的重力异常作用明显;Crust 1.0给出的地壳内界面变形可以反映深大活动断裂的深部构造变形.研究结果对于认识蒙古东西部构造特征差异,以及现今西部活动断裂的地球物理场特征具有参考意义,也可以为进一步应用Crust 1.0模型为参考开展三维密度结构反演提供一定帮助. 相似文献
17.
Ultra low frequency electromagnetic wave anomaly and its spectrum characteristics before earthquakes 总被引：1，自引：0，他引：1
Jian-Guo Hao Yun-Fu Zhang Huai-Wen Pan De-Rui Li Tian-Ming Tang Xiao-Qin Liu 《地震学报(英文版)》1995,8(1):101-109
Many observations and researches show that abundant and intense ultra low frequency (ULF) electromagnetic anomalies appeare
before local earthquakes. In order to understand this phenomenon systematically, the transmission property and the formation
of the seismic-electric dipole are discussed in this paper. The results show that the vertical component of the ULF electric
anomaly before earthquake has the properties of better penetration, less disturbance and high signal-to-noise ratio. The signal
can be easily extracted and received. The anomaly should be an important way to seek for reliable short-term and imminent
earthquake precursors. After the spectrum analysis of the (ULF) electric field anomalies, we found that the periods of the
anomaly related to local earthquakes are from a few minutes to a dozens minutes. There is a relation between the spectrum
of the anomaly and the epicentral distance. The ULF electric field anomalies strongly rely on the orientation of the seismogenic
zone. The percolation electric field anomaly and its spectrum amplitude do not have obvious relation with the size of local
earthquakes.
Contribution No. 94A0097, Institute of Geophysics, SSB, China.
The English version is improved by Prof. Guo-Hua FAN, Institute of Geophysics, State Seismological Bureau. 相似文献
18.
HUI ZHANG 《地震学报(英文版)》2000,13(2):195-202
Using finite element technique of the plane-strain problem in solid-liquid two-phase medium, we studied the characteristics of "field precursors" and "focus precursors" of subsurface fluid and their spatial-temporal evolution in case of dip-slip earthquake. The results show that: ① the change of ground fluid is slow and the anomaly is not prominent in the early period which is of elastic accumulation and non-linear; ②dilatancy emerges and anomaly focus mainly in the source region in the moderate period which is hardening and of local dilatancy. In the period the focus precursors emerge earlier than the field precursors; ③anomalies spread continuously in the source area and new regions with big anomaly emerge out of the source region in the middle-short period which is of large-scale dilatancy. 相似文献
19.
中国地震地下流体观测经过数字化改造以后, 观测资料的采样频率显著提高。 流体观测资料中的高频数据含有丰富构造信息, 为我们捕捉地震孕育及发生过程中的前兆异常信息提供了有利条件。 但是, 高频信息的出现激发了对数据分析方法改变的需求, 如何研发与数字化高频观测资料相匹配的数据处理和异常识别方法, 从高频观测数据中挖掘潜在的前兆异常信息, 成为目前地震地下研究者首要需解决的关键问题。 应用概率密度分布法对2014年鲁甸6.5级地震前南北地震带174组水位、 水温分钟值高频观测数据进行分析, 结果显示: 鲁甸6.5级地震前共有10个水位测点和7个水温测点出现高频信息异常, 异常多集中在滇西南构造带的滇中次级块体两侧, 且随着时间推移, 有向震中区逼近的变化特征。 通过对震源区及附近地区地壳结构、 构造应力作用及更大范围的区域动力演化特征进行分析, 发现异常信息的空间分布特征与川滇地区地壳运动场具有很好的一致性, 说明概率密度分布可有效反映出区域构造应力作用, 同时也验证了利用概率密度分布在流体观测数据的高频信息异常提取方面具有一定可靠性。 相似文献
20.
新疆阿尔泰6.1级地震前的地倾斜异常特征 总被引：1，自引：0，他引：1
分析了1996年3月13日新疆阿尔泰地区6．1级地震前富蕴、阿尔泰两台的地倾斜资料。结果表明资料异常具有阶段性特征。建台时间较早的富蕴台可获得趋势性异常，其时间比我国东部相应震级的略短。在短期阶段，两台的资料异常虽然出现时间有先有后，异常形式存在明显差异，但在共同形变场作用下相互关联，协同发展。根据形变场的性质及资料异常的方向性，对预估危险地点会有所帮助。资料变化停滞或异常恢复，是地震短期内就要发生的标志，可作为预报发震时间的判据。 相似文献