山西中强地震前波速比异常研究   总被引：1，自引：0，他引：1  

光春云  王赵丽 《地震》1994,(2):54-63

本文分析了大同－阳高６．１级（１９８９），５．８级（１９９１），忻州５．、１级（１９９１），侯马５．１级（１９８９）以及太原，运城１９８９－１９９１年几个４．０级左右地震前后的２０２次小震资料。结果表明：这些主震前都存在明显的地震波速异常变化，纵横波速比Ｖｐ／Ｖｓ表面为下降－回升的异常形态，负异常持续时间与震级大小相关；主震在岁异常结束后发生，滞后时间随区域地震震源深度增大而延长。同时，主震前还存  相似文献   

比值R分析及其在宁夏中强地震预报中的应用     

张东平 《地震》1994,(3):85-90

本文提出比值Ｒ分析计算方法，用其求解时间序列数据矩平差和标准差结构的分形，目的的于判定地震预报指标，作为实例，宁夏区和同心区的地震频度，最大震级，以及同心地办水氡观测数据的比值Ｒ随时间的分形变化进行了初步分析，证明本方法能为我国提供可信的震情信息。  相似文献   

Interaction among fractures and stress field computation of fracture systems   总被引：2，自引：0，他引：2  

张之立 《地震学报(英文版)》1994,7(1):43-54

ＩｎｔｅｒａｃｔｉｏｎａｍｏｎｇｆｒａｃｔｕｒｅｓａｎｄｓｔｒｅｓｓｆｉｅｌｄｃｏｍｐｕｔａｔｉｏｎｏｆｆｒａｃｔｕｒｅｓｙｓｔｅｍｓＺｈｉ－ＬｉＺＨＡＮＧ（张之立）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢ...  相似文献   

加卸载响应比理论在中强地震（7〉M≥6）预测中的应用   总被引：6，自引：2，他引：6  

陈学忠  尹祥础 《中国地震》1995,11(1):33-37

本文运用加卸载响应比理论对中强地震前的加卸载响应比的变化进行了研究。结果表明，中强地震前加卸载响应比明显上升，表现为三种不同的形态，持续时间为半年到两年。  相似文献   

区域震相强度比—岩石层热状态的有效指示     

高世玉  张廉强 《中国地震》1995,11(3):204-211

本文根据白家疃台６０年代以来的短周期地震记录图，分析了区域震相的强度比。研究表明：Ｓｎ／Ｌｇ波的强度比波传播路径上岩石层热结构、热状态及强地震活动等均有相关性，并就这种相关性对于强地震成因及其预测研究的直接意义进行了讨论。  相似文献   

主应变比异常理论在青海祁连地震预报中的应用     

李步云  陈志泰 《高原地震》1995,(1)

本文利用主应变比异常理论分析了祁连建站以来地应变观测资料，认为肃南──祁连断裂段上及附近发生的地震是由于构造应力场的变化，在引张应力状态下，正断层或走滑断层易于活动而导致的。  相似文献   

Seismic velocity-ratio in the crust and uppermost mantle in southeast Wellington province,New Zealand     

J. R. Kayal 《Pure and Applied Geophysics》1982,120(4):809-819

The regional variation of the seismic velocity-ratio () over a 200 km long traverse has been studied by means of microearthquake surveys. The Wadati-plot method is used with a minimum of four P and S arrivals for each of 49 earthquakes. The area as a whole is found to be characterized by a value of 1.74–1.76 for earthquakes of depth 12–40 km, except in a 50 km long section near Wellington, where is low at 1.60. This low has been attributed to the fault zones in the region. A small change of is observed between the upper crust (5 km) and lower crust (12 km), but there is no change of between the lower crust and uppermost mantle.  相似文献   

Total precipitable water in the atmosphere over India     

S. Rangarajan  A. Mani 《Journal of Earth System Science》1982,91(3):189-207

Electromagnetic radiation, in its passage through the atmosphere, is attenuated by absorption and scattering by atmospheric gases, dust and aerosols. The most important absorber is water vapour and the most significant parameter in atmospheric absorption studies is the total precipitable water in the atmosphere. The present paper summarises the results of a study made to compute the total precipitable water in the atmosphere over India using radiosonde and other data, as part of a programme for the computation of direct, global and diffuse solar radiation at the ground from the solar constant. Using values of air temperature and dew point from the ground up to 250 mb at 19 radiosonde stations and surface water vapour mixing ratio values at 105 surface observatories in India, precipitable water amounts have been computed for 124 stations, for each month and for the whole year. The paper describes the techniques used to extend the total precipitable water amounts derived from radiosonde data at 19 stations to 124 stations covering the major climatic zones in the country and presents the results in the form of 12 maps showing the spatial and temporal distribution of total precipitable water over India  相似文献   

Long-term erosion on granitic roadcuts based on exposed tree roots     

Walter F. Megahan  Kathleen A. Seyedbagheri  Patrick C. Dodson 《地球表面变化过程与地形》1983,8(1):19-28

Exposed roots were used to estimate soil and bedrock erosion on the cut slopes of a 45-year-old road constructed in granitic soils of the Idaho Batholith. The original roadcut surface was defined by projecting a straight line from the toe of the cut past the end of the exposed root to the intersection of a straight line projected along the surface of the hillslope. A cross-sectioning technique was then used to determine erosion to the present roadcut surface. A total of 41 exposed root sites were used to estimate erosion on a 1350 m-long section of road. Average erosion was 1·0 and 1·1 cm/year for soil and bedrock respectively. Buttressing by tree roots caused lower erosion rates for soil as compared to bedrock. Both soil and bedrock erosion rates showed statistically significant correlations with the gradients of the original cut slope. The bedrock erosion data provide a reasonable estimate of the disintegration rate of exposed granitic bedrock exhibiting the weathering and fracturing properties common to this area. The road is located in a study watershed where long-term sediment yield data are available. Sediment data from adjacent study watersheds with no roads were compared to sediment data from the roaded watershed to estimate the long-term increase in sediment yield caused by the road. The increase amounts to about 2·4 m³/year. This figure, compared to the average annual on-site road erosion, provides an erosion to sediment delivery ratio of less than 10 per cent. Based on study results, road construction and maintenance practices are suggested for helping reduce roadcut erosion.  相似文献   

Lamb's problem with the lattice model Mka3D     

C. Mariotti 《Geophysical Journal International》2007,171(2):857-864

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