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“九五”地震前兆数字化台站改造后，数字化的地磁观测仪器在全国各地磁台站推广应用已有两年多时间，两年来，数字化观测仪器和模拟记录仪器在武汉台一直进行并行观测工作，其观测资料稳定可靠。本文通过GM-3磁通门磁力仪与其它仪器进行数字和模拟观测资料的时均值、日均值、月均值、年均值对比分析。分析结果表明数字观测资料优于模拟观测资料，数字观测仪器完全可以取代模拟观测仪器。 相似文献
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The methods used for a building seismic hazard evaluation are presented with the associated results. The goals of the study are (1) to check the soil nature and the existence or not of a possible site effect around the installation and (2) to characterize the dynamic behavior of the building using ambient vibration records.
The results of the soil study with the Nakamura method are very difficult to interpret because they are not stable in space and time. The spectral ratios method has been used with regional earthquake records. The results of the application of this method allowed us to conclude that the installation was free of site effect.
The ambient vibration measurements on the building brought the conclusion to determine the first and second modes of the structure. These results have been used to calibrate numerical model. The modal shapes in plan (high roof) and in elevation (main column) have been evaluated. The damping of the building has been computed using ambient vibration records. 相似文献
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Recently, complex network approaches to time series analysis have been developed and successfully applied to geophysical records.
In this paper, the visibility graph approach is re-considered, which has been found useful as an alternative tool for describing
the fractal properties of a time series. The interpretation of various graph-theoretical measures in the context of visibility
graphs, their mutual interdependence, and their sensitivity in the presence of missing values and uncertainties (posing typical
challenges in geophysical time series analysis) are thoroughly discussed. The obtained results are illustrated for some exemplary
records from different fields of geosciences. 相似文献
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Ninety-two strong-motion earthquake records from the California region, U.S.A., have been statistically studied using principal component analysis in terms of twelve important standardized strong-motion characteristics. The first two principal components account for about 57 per cent of the total variance. Based on these two components the earthquake records are classified into nine groups in a two-dimensional principal component plane. Also a unidimensional engineering rating scale is proposed. The procedure can be used as an objective approach for classifying and rating future earthquakes. 相似文献
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近年来,由于新兴的混合采集观测系统在很大程度上提高了采集效率,因此得到了很多学者和石油公司的青睐.但在实际应用中,这种特殊观测系统的采集质量却受到很多因素的影响.一方面,该观测系统采集到的炮记录会受到相邻炮记录的干扰;另一方面,复杂的采集环境使得地震记录中包含部分空道;另外,采集过程中的场地环境干扰会不可避免地带入随机噪音,它们都会影响采集质量.虽然已有一些学者对这些因素做了相关研究,但都是单独分析,未能综合考虑各种干扰因素.本文基于稀疏约束反演的基本原理,将混合炮数据的分离、缺失道集的插值以及对随机噪音的压制问题整合在一起,通过一步处理同时减小如上三方面因素的不利影响,在改善信噪比的同时极大地提高了地震资料的处理效率.文章利用模拟数据和实际数据对这种新方法进行了验证,均得到了比较满意的效果. 相似文献
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Ocean Dynamics - The records of HW and LW in the most upper part of the Scheldt Estuary since 1971 have been analysed together with the daily river discharge. The tidal range, the hydraulic head... 相似文献
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2020年10月22日11时03分37秒四川省绵阳市北川县发生MS4.7地震,四川强震动台网与预警烈度速报台网在震区建成较密集的台站,获取了532组三分量加速度记录,有助于开展区域地震动衰减和地震动特征研究.本文对强震记录进行常规处理后计算出强震动记录的相关参数,利用克里金插值方法得到地震动峰值加速度PGA和峰值速度PGV的空间分布图,长轴呈北西—南东方向.分析强震动记录PGA、PGV随距离的衰减规律,与常用衰减关系预测值进行对比,此次地震PGA的衰减特性与俞言祥和汪素云(2006)提出的中国西部地区水平向基岩加速度衰减关系有较好的一致性.北川MS4.7地震获得的密集强震动记录为建立区域衰减关系,以及开展基于经验格林函数方法(EGFM)再现大震强地震动场展布等研究提供了重要的数据支撑. 相似文献
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长江流域降水变化及其趋势演变 总被引：1，自引：0，他引：1
本文对中国长江流域降水趋势进行了分析.指出对月降水量而言,20世纪后50年不同区域出现1不胃的降水趋势变化特征.趋势插补法研究表明中国降水时空分布趋势十分明显.对长江流域长期降水资料分析研究指出夏季月份降水时间更集中,而对年降水而言在一些站则表现出明显的周期变化. 相似文献
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火山区台站观测的地震波分析与应用 总被引：1，自引：0，他引：1
以长白山天池台记录的地震Ｐ、Ｓ波及腾冲台记录的地脉动资料为基础，分析研究了火山区台站观测的地震波在微震监测与分析、火山地震类型判别、火山区介质非均匀性与各向异性分析以及地震预报与火山喷发监测在预报中的应用． 相似文献
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Yu. M. Mikhailov G. A. Mikhailova O. V. Kapustina G. I. Druzhin S. E. Smirnov 《Geomagnetism and Aeronomy》2006,46(6):796-808
Simultaneous records of the diurnal variations in the quasistatic electric field in the near-Earth atmosphere, fluxes of discrete electromagnetic pulses in the VLF band, source azimuths, narrowband filter output emission intensity at frequencies of 4.65 and 5.3 kHz, and time forms and spectra of VLF pulses have been analyzed. The anomalous behavior of these parameters in October 2002 and August 2004 with different time delay was accompanied by earthquakes near the southeastern coast of Kamchatka at distances of 250–400 km from the registration points. Based on the results of a fine frequency-time analysis of the broadband records of VLF signals, it has been indicated for the first time that discrete electromagnetic pulses observed in anomalous fluxes before earthquakes were signals of local thunderstorm processes. 相似文献
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本文提供了1984年5月21日前后,南黄海M6．2及M6．1双主震及其前震、余震、邻震系列的“震源超极低频（0．3-3Hz）电磁辐射前兆”系列记录图（共11次地震的前兆）,并着重指出前兆记录中与地震三要素的预报直接相关的各种信息参数及其规律。 相似文献
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Himalayan region is one of the most active seismic regions in the world and many researchers have highlighted the possibility of great seismic event in the near future due to seismic gap. Seismic hazard analysis and microzonation of highly populated places in the region are mandatory in a regional scale. Region specific Ground Motion Predictive Equation (GMPE) is an important input in the seismic hazard analysis for macro- and micro-zonation studies. Few GMPEs developed in India are based on the recorded data and are applicable for a particular range of magnitudes and distances. This paper focuses on the development of a new GMPE for the Himalayan region considering both the recorded and simulated earthquakes of moment magnitude 5.3–8.7. The Finite Fault simulation model has been used for the ground motion simulation considering region specific seismotectonic parameters from the past earthquakes and source models. Simulated acceleration time histories and response spectra are compared with available records. In the absence of a large number of recorded data, simulations have been performed at unavailable locations by adopting Apparent Stations concept. Earthquakes recorded up to 2007 have been used for the development of new GMPE and earthquakes records after 2007 are used to validate new GMPE. Proposed GMPE matched very well with recorded data and also with other highly ranked GMPEs developed elsewhere and applicable for the region. Comparison of response spectra also have shown good agreement with recorded earthquake data. Quantitative analysis of residuals for the proposed GMPE and region specific GMPEs to predict Nepal–India 2011 earthquake of Mw of 5.7 records values shows that the proposed GMPE predicts Peak ground acceleration and spectral acceleration for entire distance and period range with lower percent residual when compared to exiting region specific GMPEs. 相似文献
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山东省胶东半岛两次疑难历史地震的考证 总被引：2，自引：1，他引：1
山东省的胶东半岛历史悠久,是我国文化发展较早的地区之一。根据有关史料的记载,该区曾发生过１０４６年,４９５年虞丘山两次历史地震。但在确定地震参数时,由于历史原因,对史料中记载的“虞丘山”的位置说法不一,因而,对这两次地震的震中位置和震级存在不同的意见。 相似文献
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This study considers a 35‐year record of streamwater nitrate concentration in a small agricultural catchment in south west England (Slapton Wood). The study revisits earlier work to assess whether upward trends have been maintained and how the controls upon streamwater concentration have been altered. The study has shown that (1) the catchment has reached a new position of equilibrium and increases in nitrate concentration have lessened; (2) the occurrence of severe drought in the record means that records of less than a decade are misleading and only long‐term records can illustrate changes of state; (3) the change of state observed in the catchment is illustrated in the switching of long‐term memory effects from a negative to a positive annual memory and (4) several significant long‐term impulsivity relationships with rainfall that become insignificant over the course of the study period. The study shows the importance of long‐term records in understanding changes in state in catchments and understanding the time constants of a range of driving processes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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A. B. Bhattacharya 《Annales Geophysicae》1994,12(2-3):232-239
Radar observations of nor’wester (premonsoon thunderstorm) as experienced over the Gangetic West Bengal and the integrated field intensity of atmospherics (IFIA) at 10, 20 and 30 kHz recorded over the tropical station at Calcutta have been analysed. The records of IFIA reveal that, during nor’wester, the enhancement in the signal level occurs in three different stages: (i) gradual rise of atmospherics (GRA), (ii) first sudden enhancement of atmospherics (SEA1) and (iii) second sudden enhancement of atmospherics (SEA2. Their respective occurrences have been found to be prevalent in pre-noon, latenoon and afternoon hours of a day. Of the three stages, GRA and SEA1 have been found to occur before the onset of thunderstorm, while SEA2 may even occur after its onset. A comparative study reveals that the precipitation during premonsoon thunderstorms is associated with the second sudden enhancement, while it is associated with the steady recovery of IFIA during the monsoon and postmonsoon thunderstorms. The characteristics of the first nor’wester of every year have been critically examined with an additional consideration of simultaneous radiosonde records. A probable explanation has been made in terms of the distribution of the effective sources at such times around the observing site. 相似文献
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Andriy Gnyp 《Acta Geophysica》2009,57(2):330-345
Based on the results of application of correlation analysis to records of the 2005 Mukacheve group of recurrent events and
their subsequent relocation relative to the reference event of 7 July 2005, a conclusion has been drawn that all the events
had most likely occurred on the same rup-ture plane. Station terms have been estimated for seismic stations of the Transcarpathians,
accounting for variation of seismic velocities beneath their locations as compared to the travel time tables used in the study.
In methodical aspect, potentials and usefulness of correlation analysis of seismic records for a more detailed study of seismic
processes, tectonics and geodynamics of the Carpathian region have been demonstrated. 相似文献
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The inelastic seismic response behaviour for a range of simplified single-degree-of-freedom models has been analysed using 180 random phase angle synthetic accelerograms with different frequency contents and different durations and 105 real accelerograms collected from different regions worldwide. Results from the analyses have identified that the frequency content of the excitation can greatly influence the ductility demand ratio due to inelastic amplification effects. Consequently, results derived from intraplate earthquake records (typically of higher frequency content) were generally different to those from interplate records. However, the commonly used El Centro accelerogram has significantly lower ductility demand in the low period range than the average of records with similar elastic response spectral shape. Apart from this, there was little evidence to suggest any inherent differences in the inelastic response behaviour of buildings from intraplate and interplate earthquakes which possessed similar frequency content. Thus, the average ductility demand ratios from future earthquakes in an area can be predicted by interpolation of the results presented in this paper assuming the elastic response spectrum has been defined. Ductility demand ratios derived from the synthetic accelerograms and the real accelerograms with similar frequency content have been shown to be consistent. However, results from synthetic records derived for the idealised code design spectra (such as the Uniform Building Code and the Australian Standard AS1170.4) indicate a significantly higher ductility demand in the long period range. 相似文献
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Water Resources - Bottom sediment records in Lake Oron accumulated in the recent two decades have been analyzed. Chironomid and palynological studies of 10-cm core samples of bottom sediments have... 相似文献