Evidence of earthquakes triggered by the tidal force of the sun and the moon——On the temporal characteristics of the earthquakes in Xingtai,Hejian and Tangshan     

黎凯武 《地震学报(英文版)》1998,(5)

ＩｎｔｒｏｄｕｃｔｉｏｎＵｎｔｉｌｎｏｗ,ｍａｎｙｏｂｓｅｒｖａｔｉｏｎｓａｎｄｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｉｎａｃｅｒｔａｉｎａｒｅａｓａｎｄｄｕｒｉｎｇａｃｅｒｔａｉｎｐｅｒｉｏｄｍａｊｏｒｅａｒｔｈｑｕａｋｅｓｆｒｅｑｕｅｎｔｌｙｏｃｕｒｅｄ...  相似文献   

台风脉动对地震触发作用的初探   总被引：1，自引：0，他引：1  

雷建设  陈有发 《山西地震》1998,(2):26-29

以１９４９年—１９８０年在西北太平洋形成的台风和发生在中国大陆及台湾省的地震为基础资料,通过简单分析、机理讨论和震例论证,发现存在一次台风可触发多次地震和一次地震可由多次台风触发的现象。  相似文献   

Hastening of occurrences of earthquakes due to dynamic triggering: The observation at Matsushiro, central Japan     

Takaki Iwata  Ichiro Nakanishi 《Journal of Seismology》2004,8(2):165-177

Dynamic stress/strain changes associated with the passage of seismic waves perturb the state of stress of a fault.We hypothesize that this perturbation increases the instability of the fault and that it hastens the occurrence of an earthquake that would otherwise occur somewhat later.To test this hypothesis, we investigate a time interval defined as a time difference between the occurrence of a dynamic strain change and the origin time of the first subsequent earthquake.If the occurrence of an earthquake is hastened by the strain change, the time interval would be shortened, compared with a case of a random occurrence.Here we used two datasets: 1) origin times of earthquakes at Matsushiro, Nagano Prefecture, central Japan, with magnitudes of 1.6 or greater, between November 1984 and December 1994; and 2) strainmeter records of remote earthquakes at the Matsushiro Seismological Observatory over the same period.We applied a statistical test to the distribution of the observed time intervals between dynamic strain changes due to remote earthquakes and the first earthquakes at Matsushiro subsequent to the strain changes, in order to compare it to the distribution of expected time intervals generated by a random (Monte Carlo) simulation.Because of limitations of the statistical test, we could not establish the quantitative relationship between the degree of hastening and the amplitude of the strain changes, but we found a statistically significant decrease of the observed time intervals.We also investigated the number of the earthquakes before and after the strain changes, and found that dynamic triggering has little significant impact on the occurrences of earthquakes at Matsushiro.Therefore, we conclude that dynamic triggering at Matsushiro is weaker than those reported in previous studies and that the time interval might be an important parameter for a statistical study of weak dynamic triggering.  相似文献   

The attenuation of tidal and subtidal oscillations in the Patos Lagoon estuary     

E. H. L. Fernandes  I. Mariño-Tapia  K. R. Dyer  O. O. Möller 《Ocean Dynamics》2004,54(3-4):348-359

The single, long and narrow channel that usually connects choked coastal lagoons to the ocean can serve as a natural hydraulic low-pass filter that reduces or eliminates tidal and subtidal effects inside the lagoon. This study proposes an alternative method of estimating the attenuation of the tidal and subtidal oscillations throughout the Patos Lagoon estuary. The attenuation is estimated for conditions of contrasting river runoff and weather (summer and winter). A high-pass/low-pass filter (fast fourier transformation technique – FFT) is applied to time series of sea-surface elevation (SSE) measured at the mouth of the Patos Lagoon. The resulting high-frequency (tidal) and low-frequency (subtidal) signals are used in independent simulations to force the TELEMAC-2D model. Attenuation of the tidal and subtidal signals throughout the estuary is estimated by applying cross-spectral analysis between the model-generated SSE time series at different locations throughout the estuary and the filtered SSE time series measured at the mouth. Results from the proposed method suggest that: (1) the low-frequency (subtidal) oscillations are less attenuated and propagate further than the high-frequency (tidal) oscillations in the Patos Lagoon estuary; (2) the filtering capability of the Patos Lagoon estuary is expected to follow a seasonal pattern, although further investigations on an interannual time scale are recommended in order to confirm this hypothesis; (3) the influence of the oceanic boundary processes on the SSE dynamics of the lagoon is restricted to the lower estuary. Further inland, the local forcing generated by the wind and freshwater input is likely to be the main forcing effect controlling the dynamics of the system. The proposed method proved to be an efficient and alternative way of estimating the attenuation of energy in the tidal and subtidal bands throughout the access channel of a choked coastal lagoon located in an area of reduced tidal influence.Responsible Editor: Iris Grabemann  相似文献   

Field technique of permeability tests in highly fissured limestone strata     

Adnan Al-Salihi  Abdulah Asaad 《Hydrogeology Journal》2002,10(5):566-575

A design of a dewatering system is necessary for site improvement prior to the construction of some structures. The design of an efficient dewatering system requires estimating the value of the in-situ coefficient of permeability. The available relationships for estimating the permeability coefficient were developed based on limited field measurements and conditions, and their predictions vary by several orders of magnitudes. Therefore, it was necessary to conduct field measurements of permeability and determine the relationship that best fits these measurements prior to the design of a dewatering system for specific geological and site conditions. This paper presents field measurements of permeability in complex chaotic and diagenetic limestone strata. It also offers comparative analysis of several relationships available in the literature for predicting the in-situ coefficient of permeability. The analysis is conducted for both steady and nonsteady conditions. The results show that the coefficient of permeability value is dependent on the water table level, which is affected by the tidal condition. The US Navy equation is shown to give the best correlation with field measurements. Electronic Publication  相似文献   

江苏省沿海沙洲及潮汐水道演变遥感分析   总被引：3，自引：2，他引：3  

吴曙亮  蔡则健 《国土资源遥感》2002,13(3):29-32,40

简述了不同历史阶段江苏省沿海沙洲的分布及演变情况。通过对20世纪70、80、90年代3期卫星图像的解译和对比,着重对近20a来江苏省沿海沙洲及潮汐水道的分布、变化特点和发展趋势进行了分析研究。  相似文献   

Investigation of tidal effects in lunar laser ranging     

J. Müller  V. Tesmer 《Journal of Geodesy》2002,76(4):232-237

 The analysis of lunar laser ranging (LLR) data enables the determination of many parameters of the Earth–Moon system, such as lunar gravity coefficients, reflector and station coordinates which contribute to the realisation of the International Terrestrial Reference Frame 2000 (ITRF 2000), Earth orientation parameters [EOPs, which contribute to the global EOP solutions at the International Earth Rotation Service (IERS)] or quantities which parameterise relativistic effects in the solar system. The big advantage of LLR is the long time span of lunar observations (1970–2000). The accuracy of the normal points nowadays is about 1 cm.  The capability of LLR to determine tidal parameters is investigated. In principle, it could be assumed that LLR would contribute greatly to the investigation of tidal effects, because the Moon is the most important tide-generating body. In this respect some special topics such as treatment of the permanent tide and the effect of atmospheric loading are addressed and results for the tidal parameters h ₂ and l ₂ as well as values for the eight main tides are given. Received: 14 August 2000 / Accepted: 15 October 2001  相似文献   

地震应力触发研究   总被引：39，自引：8，他引：39       下载免费PDF全文

万永革  吴忠良  周公威  黄静  秦立新 《地震学报》2002,24(5):533-551

介绍地震应力触发基本理论．从地震静态和动态应力触发、粘弹性模型在地震应力触发中的应用、火山喷发或爆炸与地震触发及地震触发的其它解释等几个方面，综述近年来地震应力触发的研究进展，并对地震应力触发研究近期的发展进行展望．   相似文献   

甘肃省东部地区的潮汐测量结果及其地球动力学意义   总被引：3，自引：2，他引：3  

唐九安  常千军 《地震》1995,(3):252-259

文中介绍甘肃省东部地区1985年以来在重力、倾斜、水平应变和水位等固体潮方面的测量概况,给出了各台(项)全系列观测资料作整体调和分析计算的潮汐参数,分析了液态地核共振效应对重力、水平线应变和水位固体潮周日波潮汐因子的影响以及地壳构造横向不均匀性对倾斜固体潮潮汐因子的影响。结果表明,兰州重力仪、石英水平伸缩仪和甘06井等水位井的结果清楚地显示出液核共振效应对K_1波振幅的缩小作用和对ψ_1波振幅的放大作用,且重力和伸缩仪NS向结果所揭示的地球模型更接近莫洛金斯基的地球型Ⅱ;倾斜固体潮潮汐因子的实测结果明显地受地壳构造横向不均匀性影响,其中水管倾斜仪受影响的程度又明显地大于水平摆倾斜仪,兰州和宕昌两地南北向的非均匀性明显大于东西向,而宕昌地区的非均匀性又明显大于兰州地区。  相似文献   

云南及邻区Ms≥6.0级地震的重力异常指标体系研究     

刘仲全 《地震研究》1995,18(4):378-387

本文对云南省昆明台和弥渡台多年的重力观测资料进行了潮汐变化和非潮汐变化的系统研究，总结了异常特征，给出了云南及邻区的Ｍｓ≥６．０级地震重力异常指标体系和震级与重力异常幅度、时间及震中距的统计公式。结果表明，潮汐变化中的重力潮汐因子变化对地震的反映较好，其对应率较高。  相似文献