构造地质学计算机辅助教学课件SGCAI

构造地质学计算机辅助教学课件（ＳＧＣＡＩ）利用数据库，图形动画及多媒体等技术，对地质学基础课程的计算机辅助教学研究作了初步探索，课件分为学生学习，教师管理，附属功能和执行四大模块，具有学习选择，图片说明，动画演示，练习测验，辅导答题等十个功能，课件设计新颖，技术全面，使用方便，使用该课件能充分调动学生学习的主观能动性，使学生成为真正的学习主体，有助于提高教学质量。     

Comparison of Aircraft and Ground-Based FluxMeasurements during OASIS95

Aircraft and ground-based measurements made during the1995 Australian OASIS field campaign are compared. The aircraft data were recorded during low-level flightsat 6 m above ground level and grid flights at altitudes of between 15 and 65 m, allin unstable atmospheric conditions. The low-level flights revealed an inadequate temperaturesensor response time, a correction for which was determined from subsequent work ina wind tunnel. Aircraft and ground-based measurements of mean wind speed, wind directionand air temperature agree to within 0.2 m s^-1, 4° and 0.9 °C respectively.Comparisons between aircraft and ground-based observations of the standarddeviations of vertical velocity, horizontal wind speed, air temperature and specifichumidity have slopes of 0.96, 0.97, 0.92 and 0.99 respectively but the observed scatter isroughly twice the random error expected due to the averaging length of the aircraft data andthe averaging period of the ground-based data. For the low-level flights, the ground-basedand aircraft measurements of sensible and latent heat flux show mean differences of 27 and-25 W m^-2 respectively, which reduce to 11 and -4 W m^-2 respectivelywhen analysis of aircraft data is limited to areas immediately adjacent to the fluxtowers. For the flights at 15 to 65 m above ground level, the mean differences between theground-based and aircraft measurements of sensible and latent heat flux are -22 and-1 W m^-2 respectively and these change to -1 and -7 W m^-2 respectively oncethe effect of surface heterogeneity is included. Aircraft and ground-based measurementsof net radiation agree to within 6% at one ground-based site but differ by 20% at a second.Aircraft measurements of friction velocity at 6 m above the ground agree well withground-based data, but those from flights between 15 and 65 m above ground level do not.This is because at these heights the aircraft measurements provide the local shear stress,not the surface shear stress. Overall, the level of agreement allows confidence in the aircraftdata provided due care is taken of instrument response times and differences in thesurfaces sampled by aircraft and ground-based systems.     

Recent Progress and Future Prospects in Solar Physics, and Their Relevance for Planet Earth

Understanding our star, the Sun, is of fundamental interest for life on Earth. In this paper, the status of knowledge in solar physics of roughly two decades ago is summarised, and the most recent developments in this very active field are shown, many of them achieved by means of space based missions. The Sun–Earth connection is described and, finally, an outlook on future solar research is given.     

Historical measurements of the Earth's magnetic field compared with remanence directions from lava flows in Italy over the last four centuries

Direct measurements of the Earth's magnetic field in Italy since 1640 a.d. have been used to check the remanence directions derived from historically dated volcanic rocks of Etna and Vesuvius. Direct measurements consist of the records of L’Aquila and Pola geomagnetic observatories, the repeat stations of the Italian Magnetic Network and the data base of the Historical Italian Geomagnetic Data Catalogue. All have been relocated to the same reference site (Viterbo — lat. 42.45°N, long. 12.03°E) in order to draw a reference secular variation (SV) curve. The direction of the Earth's field at Viterbo has also been calculated from the historical records (2000-1600) of ref. [Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of geomagnetic secular variation from historical records. Phil. Trans. R. Soc. London, Ser. A 358, 957-990] database. The remanence directions from Etna show a general agreement with the trend of the SV curve, although their inclination is usually lower than that from the direct measurement. The directions from Vesuvius are more scattered. Large discrepancies occur at both volcanoes and in some cases have been ascribed in the literature to poor geographic information, making it difficult to identify the flows actually emplaced during the eruptions reported in the chronicles. Closer examination shows that the great majority of the best-defined remanence directions (semi-angle of confidence α₉₅ < 2.5°) deviate significantly from the geomagnetic direction measured at the time of the emplacement, the angle between the two directions being larger than the α₉₅ value. The value of 2.5-3.0° can thus be regarded as a conservative evaluation of the error when dealing with dating Etna and Vesuvius lava flows older than 17th century, even when the accuracy attained in remanence measurements is higher. In default of a SV curve for Italy derived from archaeological artefacts, a further error in dating is introduced when reference is made to SV curves of other countries, even if well-established, as these are from regions too far from Italy (>600 km) to confidently relocate magnetic directions.     

Ground deformation of Nisyros Volcano (Greece) for the period 1995–2002: Results from DInSAR and DGPS observations

Differential GPS (DGPS) and Differential Interferometric Synthetic Aperture Radar (DInSAR) analyses were applied to the Kos-Yali-Nisyros Volcanic Field (SE Hellenic Volcanic Arc) to quantify the ground deformation of Nisyros Volcano. After intense seismic activity in 1996, a GPS network was installed in June 1997 and re-occupied annually up to 2002. A general uplift ranging from 14 to 140 mm was determined at all stations of the network. The corresponding horizontal displacements ranged from 13 to 53 mm. The displacement vectors indicate that the island is undergoing extension towards the East, West and South. A two-source “Mogi” model combined with assumed motion along the Mandraki Fault was constructed to fit the observed deformation. The best-fit model assumes sources at a depth of 5500 m NW of the centre of the island and at 6500 m offshore ESE of Yali Island. DInSAR analysis using four pairs of images taken between May 1995 and September 2000 suggests that deformation was occurring during 1995 before the start of the seismic crisis. An amplitude of at least 56 mm along the slant range appeared for the period 1996 through 1999. This deformation is consistent with the two-source model invoked in DGPS modelling. Surface evidence of ground deformation is expressed in the contemporaneous reactivation of the Mandraki Fault. In addition, a 600 m long N-S trending irregular rupture in the caldera floor was formed between 2001 and 2002. This rupture is interpreted as the release of surface stress in the consolidated epiclastic and hydrothermal sediments of the caldera floor.     

Directional dependence of P- and S-wave propagation and polarization in foliated rocks from the Kola superdeep well: Evidence from laboratory measurements and calculations based on TOF neutron diffraction

We have measured P- and S-wave velocities on two amphibolite and two gneiss samples from the Kola superdeep borehole as a function of pressure (up to 600 MPa) and temperature (up to 600 °C). The velocity measurements include compressional (Vp) and shear wave velocities (Vs1, Vs2) propagating in three orthogonal directions which were in general not parallel to inherent rock symmetry axes or planes. The measurements are accompanied by 3D-velocities calculations based on lattice preferred orientation (LPO) obtained by TOF (Time Of Flight) neutron diffraction analysis which allows the investigation of bulk volumes up to several cubic centimetres due to the high penetration depth of neutrons. The LPO-based numerical velocity calculations give important information on the different contribution of the various rock-forming minerals to bulk elastic anisotropy and on the relations of seismic anisotropy, shear wave splitting, and shear wave polarization to the structural reference frame (foliation and lineation). Comparison with measured velocities obtained for the three propagation directions that were not in accordance with the structural frame of the rocks (foliation and lineation) demonstrate that for shear waves propagating through anisotropic rocks the vibration directions are as important as the propagation directions. The study demonstrates that proper measurement of shear wave splitting by means of two orthogonal polarized sending and receiving shear wave transducers is only possible when their propagation and polarization directions are parallel and normal to foliation and lineation, respectively.     

临震前地壳变形不动点现象与机制研究

在综合分析国内外地形变前兆研究现状的基础上,结合汶川8.0级地震前GPS、应变、重力等研究结果,提出临震前震源区域可能出现变形不动点现象。地壳变形过程中的不动点现象是临震前区域应力场进入临界状态的重要标志,是地震潜在危险区域划定的重要依据。借助不动点理论,给出汶川地震前变形不动点集合的演化,结合大区域地震活动空区与远场显著形变异常分布,探讨变形不动点现象发生的动力学背景,验证了汶川地震前地壳变形的不动点现象是大区域应力场有序运动的结果。     

某双向混凝土立交桥顶推法施工控制测量

文中所选立交桥为双向三车道桥梁,单幅为3跨105 m的箱型连续梁,重量3 400 t,横跨铁路线。对于跨铁路的桥梁建设,顶推法施工可最大限度地减少对交通的影响。桥梁重量大,所须牵引力约280 t,施工过程中对桥墩及其他建筑物产生的变形较大,施工前模拟施工状态,设计控制测量监控的基本方案,利用控制测量方法,对施工状态实时监测,预测变形及偏位、纠偏,使施工状态最大限度地接近理想状态。顶推到位后,轴向偏位满足1 cm的限差,桥墩变形基本满足施工规范的要求,最终顺利完成顶推过程。