蚌埠台电磁波异常

1.观测系统概况蚌埠电磁波台始建于1984年10月,1986年正式观测,目前已有近五年的连续资料。该台地理坐标为东经117°18′,北纬30°54′,台基为花岗岩。记录器为DJ—1型地震记录仪。传感器有半埋地框天线一道(8m×15m),地下部分1.5m,垂直埋设,法向东西,约30匝     

SEDIMENT PROBLEMS AT DUJIANGYAN PROJECT

1. THE GEOGRAPHICAL ENVIRONMENT AND HISTORICAL PERSPECTIVE OF THEPROJECTIn the western part of Sichuan Basin, between the Longmen Mountain in the west and theLongquan Mountain in the southeast, lies an alluvial plain of 6500 kmZ formed by the Minjiang Riversystem known as the Chengdu Plain. With its mild climate (average annual temperature 16' 4 C ),fertile soils, rich water resources, and the densely interconnected system of Minjiang and TuojiangRivers, Chengdu …     

SEDIMENT MANAGEMENT AT HYDROPOWER RESSERVOIRS

ICONDUCTINGASEDIMENTATIONSURVEYTOCONFIRMISSUESIn1996,ElectricPowerResearchinstitilteandtheFERCjointlyconductedasedimentationsurveyofprimarilyNFHPreservoirsintheUnitedstates.Theprimarypurposesofthesurveyweref(l)toascertainthescopeandseriousnessofsedimentationproblemsinthereservoirs,(2)toexplorethefeasibilityofapplyingmoderntechnologiestomitigatesedimentationproblems,(3)todeterminetheneedsfortechnicalguidelines,(4)toassistFERCstaffinthelicensingofhydroelectricprojectswith…     

地震危险性估计的一种尝试

本文根据三角网统一平差和跨断层测量资料，利用位错理论的反演方法，计算了唐山和北京，怀来地区几条主要断层滑动速率和滑动方向，其结果与我们用有限元方法计算的断层应力场配套。并获得三点结果：（１）断层滑动速率大，则断层上庆力高，反之亦然；（２）断层滑动方向与断层应力场方向配套；（３）当跨断层短线大度年变化持续出现线笥关系时，断层浅部与深部滑动一致，而且断层浅部滑速率大，此却表示有发生地震的危险性。     

SYNTHETIC SEISMOGRAMS AT NON-VERTICAL INCIDENCE*

Synthetic seismograms are usually computed for reflections from vertical incidence of P waves for a horizontally layered medium. In actual practice the angle of incidence departs from the vertical, as receivers are usually located at some distance from the source. At angles other than the vertical, the conversion of P- to S-wave energy and changes in the reflection coefficient affect the shape of the synthetic seismograms. The effect of non-vertical incidence on synthetic seismograms is examined in this paper. Seismograms at non-vertical incidence have been computed using the plane-wave approach of Haskell (1953) for a layered medium. The use of plane waves is an approximation to the actual case of spherical wavefronts from a surface source. Using plane-wave theory, the expected wave forms as a function of angle of incidence were computed numerically for several simple models. The results indicate that the synthetic seismograms do not change significantly for angles of incidence between o and 25 degrees. For larger angles the changes in the wave forms may be severe. The effect is more pronounced for high-velocity layers than for low-velocity layers.     

泉州重力潮汐观测的分析

为了研究海潮与固体潮的相互作用,对近海的泉州台用三台重力仪（二台LaGoste-G型、一台GS型）为期四个半月的观测资料进行了初步分析,探讨了仪器的性能及误差来源。由分析得出: 1.由LaCoste-G型584和589重力仪观测得到的结果是一致的,三台仪器对于主要潮波O₁和M₂波的观测结果也相符较好,其互差不超过8‰。利用Schwiderski图和我国等潮图作海潮改正后的潮汐因子接近理论模型值。但由于泉州为近海台,大的余差可能反映了局部地区海潮的影响。 2.LaCoste-G型重力仪的误差主要来自灵敏度的变化,应在基本台上作定期标定。 3.GS-207重力仪的观测结果受气压的影响较大,特别是K₁和S₂波,经初步分析得出约7微伽/毫巴。     

长白山天池火山区的谐频事件

通过对长白山天池火山地区2002、2003和2005年夏季3期流动地震观测资料的频谱分析,发现火山口附近存在一种在频率域中形态比较特殊的地震事件,其频谱由1组等间隔的谱峰构成,峰值振幅随频率缓慢变化,形态与时间域中的谐波信号相似,我们把这种地震事件称为谐频事件。在3个夏季的流动观测中,共发现38个谐频事件,且这些事件大多与震群活动有关。分析表明,谐频地震频谱中的谐波现象与震源有关,可能是岩石破裂过程中,在特殊激发条件下,裂缝壁和裂缝内部岩浆或热液的压力扰动相互作用产生的。我们认为近年来长白山天池地震活动的突然增加和谐频事件的出现与深部岩浆的侵入活动有关     

EROSION PROCESSES AT THE HILLSLOPE SCALE

The results are presented of an intensive monitoring programme to determine eroded volumes due to observed rainfall events on a hillslope surface. The surface investigated has been reproduced through a digital elevation model and analysed in terms of drainage network, contributing area and slope by performing planimetric and altimetric analysis. Erosion maps were derived from a comparison of consecutive digital elevation models relative to time. These maps reveal the spatial and temporal evolution of the erosion process at the hillslope scale. The erosion was uniform across the surface, supporting the assumption of randomness in the erosion process commonly used in surface drainage development models. The observed value of erosion has been estimated at approximately 0.11 m/m² per year, with almost 500 mm of total annual rainfall.     

武昌同步卫星信号振幅闪烁功率谱

本文利用自制的微机数据采集与分析系统,处理了1985年12月至1986年6月在武昌接收日本ETS-Ⅱ卫星信标136MHz信号所观测到的振幅闪烁。共分析了133例闪烁功率谱得出,谱指数随闪烁指数S_4的增加有增大的趋势,平均谱指数值为3.1;大多数的对数功率谱曲线都在低频部分平坦或以略小于1的斜率上升,而在高频部分以-2.5～-4.0的斜率迅速下降;有1 3例功率谱在高频部分发生“折断”现象,即负幂律谱有两个谱指数,发生折断的频率f_b约为0.07Hz,相应的电离层不规则结构的空间尺度约为280m。     

地球磁层顶的无碰撞Kelvin-Helmholtz不稳定性（Ⅰ）

本文用无碰撞等离子体的CGL近似,讨论了地球磁层顶的Kelvin-Helmholtz（K-H）不稳定性问题。同可压缩MHD近似一样,CGL等离子体也存在下、上两个临界速度v_c和v_u。不稳定性仅当v_c<₀ cosα<_u时才能激发,v₀为磁鞘等离子体流速,α为v₀和切向波矢k_t间的夹角。在向阳面低纬区,时间增长率ε和空间增长率κ与可压缩MHD的相应值相近。当v₀ cosα≥v_u时,不稳定表面波转化为稳定的体波。各向异性对K-H不稳定性有显著影响。在近日点低纬处,若磁鞘各向异性参数S₂接近水龙带不稳定性的阈值,很小的v₀便能激发不稳定表面波。S₂低于极小值S₂^min时,不稳定性不可能产生。所谓Overstability现象是不存在的。     

磁层亚暴期间高纬地区三维电流体系

确定亚暴期间高纬地区的三维电流体系是磁层和电离层物理的基本问题之一,本文简述了近年来发展的根据地面地磁活动的记录及演三维电流体系的两种较新的方法:KRM（Kamide-Richmond-Matsushita）方法和K（Kisabeth）方法.在KRM方法和许多其它类似的计算中,都假定磁力线是垂直于电离层沿地球径向的直线.本文介绍了一种递推方法,可计算场向电流沿弯曲的偶极子场线流动的情况。同时,还介绍了高纬三维电流体系对亚暴期间中低纬度地磁扰动的贡献。最后介绍了在计算电流体系时所需的电离层电导率模式。     

佐署地震台供电电源改造

从佐署地震台的供电问题和负载用电特点出发,说明采用可靠性较高的GL-3BR型直流电源替换原来的在线式UPS不间断电源电源的可行性和替换方法,以保障地震台观测系统连续可靠运行。     

唐山大震后邢台、海城老震区的同步"颤扰"现象

1.前言1976年7月28日唐山7.8级地震后,从对观测资料的分析中作者发现了一种特殊现象:在邢台地区的红山地震台记录到唐山大震区的强余震后10小时之内,邢台地区发生的小震的初动方向与唐山强余震有很好的一致性。为了检验其可靠性,作者同时也将石硼峪地震台记录的唐山强余震与海城地区发生的小震作同样的分析对比,发现该台在同样的时段内记录的海     

MELTWATER FLUXES AT AN ARCTIC FOREST-TUNDRA SITE

Models of surface energy balance and snow metamorphism are utilized to predict the energy and meltwater fluxes at an Arctic site in the forest–tundra transition zone of north-western Canada. The surface energy balance during the melt period is modelled using an hourly bulk aerodynamic approach. Once a snowcover becomes patchy, advection from the bare patches to the snow-covered areas results in a large spatial variation in basin snowmelt. In order to illustrate the importance of small-scale, horizontal advection, a simple parameterization scheme using sensible heat fluxes from snow free areas was tested. This scheme estimates the maximum horizontal advection of sensible heat from the bare patches to the snow-covered areas. Calculated melt was routed through the measured snowcover in each landscape type using a variable flow path, meltwater percolation model. This allowed the determination of the spatial variability in the timing and magnitude of meltwater release for runoff. Model results indicate that the initial release of meltwater first occurred on the shallow upland tundra sites, but meltwater release did not occur until nearly two weeks later on the deep drift snowcovers. During these early periods of melt, not all meltwater is available for runoff. Instead, there is a period when some snowpacks are only partially contributing to runoff, and the spatial variation of runoff contribution corresponds to landscape type. Comparisons of melt with and without advection suggests that advection is an important process controlling the timing of basin snowmelt.     

一种利用单台强震记录计算任意场地三分量地面运动的方法

本文利用近场理论格林函数反褶积的方法计算土层的地震反应.解答中包含了产生地面运动的各种反射、透射和转换波震相,也计入了土层与基底介质的相互作用.将计算的土层响应与已获得的近场加速度记录褶积,可算出不同土层场地上垂直向和水平向三分量的地面运动.文中利用1982年卢龙地震的近场加速度记录,检验了方法的可行性.     

一种利用单台强震记录计算任意场地三分量地面运动的方法

本文利用近场理论格林函数反褶积的方法计算土层的地震反应.解答中包含了产生地面运动的各种反射、透射和转换波震相,也计入了土层与基底介质的相互作用.将计算的土层响应与已获得的近场加速度记录褶积,可算出不同土层场地上垂直向和水平向三分量的地面运动.文中利用1982年卢龙地震的近场加速度记录,检验了方法的可行性.     

NATURAL POLARIZATION STUDIES AT BALCOVA GEOTHERMAL FIELD*

Contrasting resistivity, temperature, pressure, porosity and fluid migrations are the main causes of ion accumulations along the discontinuities which create coupling-induced natural current flow which is observed as the Natural Polarization Potential (NPP) on the surface. Natural Polarization Electric Field (NPE) variations were recorded along 13 profiles about 2.5 km each in a north-south direction. Interpretation of the coincident anomalies of the NPP and the NPE field resulted in determination of the polarization angle, polarization focal depth and the azimuths of the polarized interfaces. Considerable agreement between faults delineated by previous geological and geophysical investigations and polarization discontinuities was observed. The polarization plane was observed to be horizontal in high temperature areas but steepened gradually in relatively colder regions in the northern coastal area. From the polarization depth distribution two depression zones were observed, separated by an uplifted section elongated in a north-south direction. The basin at the eastern side had an estimated polarization depth of 1.1 km and was limited by the Agamemnon-2 and -1 faults, while the western basin had an estimated depth of 1.3 km and extended in the east-west direction not previously reported. The eastern basin extends on the north side around the town of Inciralti, the western basin appeared to be elongated towards the town of Cesme.     

嘉山台自然电位研究

本文使用嘉山地电台自１９７４年建台以来近２０年的自然电位日均值，研究了该台自然电位与附近３００ＫＭ范围内ＭＬ≥４．５地震的关系，根据１９７９年的实验数据分析初步推测，该东台西向自然电位在七十年代与中强震较好的对应关系可能是由于西测量电极埋在对地震孕育敏感的部位所致。震前由于局域应力场的变化引起地下水流动和渗流的变化，影响到西测量电极周围的水文物理条件或化学条件的变化，从而造成东西方向自然电位大幅度