Site amplification at Avcılar, Istanbul     

M. Ergin  S. zalaybey  M. Aktar  M.N. Yalin 《Tectonophysics》2004,391(1-4):335

Avcılar is the suburb of Istanbul that was most heavily damaged during the August 17, 1999 M_w 7.4 Izmit earthquake. Strong ground motion caused fatalities and damage in Avcılar despite being 90 km from the epicenter. We deployed five portable seismograph stations equipped with Reftek 24-bit recorders and L4C-3D seismometers for 2 months, in order to understand why the local site response was different from elsewhere in Istanbul. A reference station was placed on a hard rock site, and the remaining four stations were placed on other geological units, in areas that had experienced varying levels of damage. We calculated frequency-dependent ground amplification curves by taking the ratios of the spectra at soft and hard rock sites. We obtained similar site response curves for most earthquakes at each site in the frequency range of 0.3–1.6 Hz, and observed no significant site amplification beyond 2.0 Hz at any site. The overall characteristics of the recorded S-waveforms and our modeling of the calculated site amplification curves are consistent with amplification as a result of trapping of seismic energy within a 100–150 m thick, low-velocity subsurface layer. We also review the applicability of microtremor measurements to estimate local site effects at Avcılar. For these data, we used ratios of spectra of horizontal to vertical components to obtain each site response. These results are compared with standard spectral ratios. These microtremor measurements provide consistent estimates of the amplification at most sites at the higher end of the frequency band, namely above 1 Hz. The results from both methods indeed agree well in this part of the frequency band. However, the microtremor method fails to detect amplification at lower frequencies, namely <1.0 Hz.  相似文献   

V6-A电磁系统山区水源勘测中的应用     

张杰 《地下水》2005,27(6):487-488,496

本文介绍V6-A电磁系统的设备原理、特点,控源音频大地电磁法,野外数据采集的方法;结合实例说明了V6-A电磁系统在山区找水中的应用效果.  相似文献   

基于DEM的地层界线V字型法则实现     

李伟忠  温彦平 《地质与勘探》2005,41(5):58-61

地质人员经常依照V字型法则连接地层出露界线,但因其随意性和局限性容易出现误差和错误.基于GIS的机助地质填图系统中,基于等高线求取界线由于等高线的不连续性有着明显的局限性.为此,在DEM形成的三维空间中通过求解DEM与空间平面交线的方法来获取地质界线,可以有效地提高精度.文章分析探讨了基于不规则三角形网的地层界线求取思路,并通过实际例子对V字型法则给以实现,结果证明该方法执行速度较快、精度高.  相似文献   

Field meeting: Coastal Suffolk Crag weekend, 23-25 April 2004     

R.G. Dixon 《Proceedings of the Geologists' Association. Geologists' Association》2005,116(2):149-160

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Comparisons, processing and interpretation of the surveyed data by GMS-06 and other magnetotelluric sounding systems     

于鹏吴健生  王家林张新兵 《地震学报(英文版)》2006,19(5):596-600

In recent years, the data collecting and processing of magnetotelluric sounding （MT） have progressed greatly. How to improve the quality of field surveyed data and obtain the high quality parameters such as apparent resistivity and phase is the most important link during the overall flow. It is closely related to the signal-to-noise ratio of magnetic sensors, the resolution of data collecting units and relevant processing methods as well. Produced by Germany Metronix Measurement Instruments and Electronics Ltd., the new type multi-channel geophysical measurement system GMS-06 was already adopted and used by domeslic units such as Institute of Geology and Geophysics of Chinese Academy of Sciences and Tongji University. Based on the brief introduction of GMS-06, this paper will give the comparisons and analyses of the synchronous surveyed MT data by GMS-06, MMS-03 MT system which was also produced by Metronix and V5-2000 MT system produced by Canada Phoenix Geophysics Ltd.. Then the preliminary processing and interpretation results of the long period MT data observed by GMS-06 in the area of Shanghai and Zhejiang are also discussed in the paper.  相似文献   

Determination of the Trace Refractory Elements V, Nb and Ta in Environmental Samples by ICP-MS After Separation and Preconcentration with Nanometre-Sized Alumina Microcolumns Following Chemical Modification by Gallic Acid     

Xuli Pu  Chaozhang Huang  Bin Hu  Zucheng Jiang 《Geostandards and Geoanalytical Research》2006,30(2):97-105

Nanometre-sized alumina was chemically modified with gallic acid (GA) and used as a solid phase adsorption material for the determination of trace amounts of V, Nb and Ta in natural water, soil and stream sediment samples by inductively coupled plasma-mass spectrometry. The effects of pH, sample flow rate and volume, elution solution and interfering ions on the recovery of the analytes were investigated. The results showed that V, Nb and Ta could be adsorbed at pH 4.0 and recovered with 1 ml of 2.0 mol l^-1 HCl. Under optimised conditions, the adsorption capacity of GA-modified nanometre-sized Al₂O₃ was found to be 7.0, 8.9, 13.3 mg g^-1 for V, Nb and Ta, respectively. The limits of detection were as low as 0.25, 0.24 and 0.66 ng l^-1 for V, Nb and Ta, respectively with a concentration factor of fifty. The recovery of V, Nb and Ta for spiked water samples was between 85.7 and 116%. The developed method has also been applied to the determination of trace V, Nb and Ta in soil and stream sediment certified materials, and the determined values were in a good agreement with the certified values.  相似文献   

Echoes from an irradiated disc in GRO J1655–40     

Hynes  O''Brien  Keith Horne  Chen  & Haswell 《Monthly notices of the Royal Astronomical Society》1998,299(4):L37-L41

Oscillations observed in the light curve of Nova V1974 Cygni 1992 since the summer of 1994 have been interpreted as permanent superhumps. From simple calculations based on the tidal disc instability model of Osaki, and assuming that the accretion disc is the dominant optical source in the binary system, we predict that the nova will evolve to become an SU UMa system as its brightness declines from its present value by another 2–3 mag. Linear extrapolation of its current rate of fading (in magnitude units) puts the time of this phase transition within the next 2–4 yr. Alternatively, the brightness decline will stop before the nova reaches that level, and the system will continue to show permanent superhumps in its light curve. It will then be similar to two other old novae, V603 Aql and CP Pup, which still display the permanent superhump phenomenon 80 and 56 yr, respectively, after their eruptions. We suggest that non-magnetic novae with short orbital periods could be progenitors of permanent superhump systems.  相似文献   

农业技术转移决策支持系统(DSSAT)新进展   总被引：10，自引：0，他引：10  

罗群英  林而达 《气象》1996,22(12):10-13

农业技术转移决策支持系统ＤＳＳＡＴ Ｖ３是现阶段比较成熟的作物生产管理计算机决策支持系统，和其前代版本ＤＳＳＡＴＶ２．１相比，它具有更大的灵活性和更完善的功能。作者以近年来对ＤＳＳＡＴ的研究和实践为基础，从ＤＳＳＡＴ Ｖ３外壳和作物模型两方面来阐述其新特点以及应用前景。  相似文献   

旋转针锥光下一光轴出露时快速测定2V的图解     

高凡 《矿物学报》1988,(2)

为了简化旋转针锥光下一光轴出露时测定2V的赤平投影法的绘图手续,设计了本图解,只要测取θ,R,R′与φ四值,就能更快地求得2V值。  相似文献   

Porphyrin geochemistry of Atlantic Jurassic-Cretaceous black shales     

Earl W. Baker  J. William Louda   《Organic Geochemistry》1986,10(4-6)

Late Jurassic-early Cretaceous black shales and an overlying sequence of Albian-Campanian zeolitic claystones from the Falkland Plateau (DSDP/IPOD Leg 71, Site 511) were analyzed for tetrapyrrole pigment type and abundance. The “black shale” sequence was found to be rich in DPEP-series dominated free-base, nickel (Ni) and, to a lesser extent, vanadyl (V = 0) porphyrins. A low level of organic maturity (i.e. precatagenesis) is indicated for these strata as nickel chelation by free-base porphyrins is only 50–75% complete, proceeding down-hole to 627 meters sub-bottom. Electronic and mass spectral data reveal that the proposed benzo-DPEP (BD) and tetrahydrobenzo-DPEP (THBD) series are present in the free-base and Ni species, as well as the more usual occurrence in V = 0 porphyrin arrays. Highly reducing conditions are suggested by an abundance of the PAH perylene, substantial amounts of the THBD/BD series and a redox equilibrium between free-base DPEP and 7,8-dihydro-DPEP series, which exist in a 7:1 molar ratio. The Albian-Campanian claystone strata were found to be tetrapyrrolepoor, and those pigments present were typed as Cu/Ni highly dealkylated (C₂₆ max.) etioporphyrins, thought to be derived via redeposition and oxidation of terrestrial organic matter (OM). Results from the present study are correlated to our past analyses of Jurassic-Cretaceous sediments from Atlantic margins in an effort to relate tetrapyrrole quality and quantity to basin evolution and OM sources in the proto-Atlantic.  相似文献