我国高碘卤水分布规律及其形成(续1)——世界高碘卤水的分布回顾

根据国内外大量实际资料,从碘的分布情况及其所处的地质条件,结合石油和天然气形成过程、油气藏类型及其分布特点,探讨高碘卤水分布的规律及其形成条件,在此基础上指出了我国的找碘方向。     

Error inflation in Probabilistic Seismic Hazard Analysis

Based on a consistent interpretation of earthquake occurrence as a stochastic process I demonstrate that the mathematical model of Probabilistic Seismic Hazard Analysis (PSHA) as it is in use today is inaccurate and leads to systematic errors in the calculation process. These mathematical errors may be regarded as an important contributor to the unrealistic results obtained by traditional PSHA for low probabilities of exceedance in recent projects.     

Ground subsidence,Quaternary faults and vulnerability of utilities and transportation networks in Thessaly,Greece

Ground fissures and subsidence have caused extensive damage in structures and the utility networks (roads, railroad line, Larisa NATO airport, telecommunication network) in the plain of Thessaly, central Greece, in the last 20 years. The fact that these fissures are parallel to Quaternary faults controlling the structural evolution of the Thessaly basin, marked by intense recent seismic activity, led some scientists to regard them as manifestation of tectonic creep, even premonitory phenomena of major future seismic events. A careful study of the geometric characteristics and of the kinematics of these ground fissures, however, revealed that they only reflect shear failure of the ground due to compaction of loose sediments following significant decline of the groundwater level due to over-pumping; i.e. a geotechnical and not a tectonic process. Furthermore, theoretical considerations and modeling predict surface fissuring along zones of anomalous basement, normal-fault controlled topography. This explains the correlation between ground fissures and active Quaternary normal faults.     

Ground reinforced embankments for rockfall protection: design and evaluation of full scale tests

Infrastructures such as roads and railways as well as urbanised areas, in mountainside regions, can frequently be endangered by rockfalls and, therefore, need to be protected against the impact of rolling blocks. Among the various protection works that can be used, ground reinforced embankments can be considered a feasible technique. A set of full-scale tests on embankments made of ground reinforced by geogrids are presented and discussed. The experiments were performed in a specifically designed and constructed test facility, where concrete blocks up to 9,000 kg in weight were thrown onto a geogrid reinforced embankment at a speed of about 30 m/s. Several embankments made of different geogrid types, different soils and construction layouts were tested at different impact energy levels, permitting a quantitative assessment of the resistance impact of these structures. The experimental results were compared with those obtained from a dynamic finite element method numerical model, and a good agreement was obtained.     

Crustal deformation in the Central Ionian Islands (Greece): Results from DGPS and DInSAR analyses (1995–2006)

Ground deformation studies based on Differential GPS (DGPS) and Differential Interferometric SAR (DInSAR) analyses have been conducted in the seismically active area of the Central Ionian Islands. Local GPS networks were installed in Cephallonia (2001) and Zakynthos (2005). The Cephallonian network has been remeasured five times and Zakynthos' once as of July 2006. The studies have yielded detailed information regarding both local and regional deformations that are occurring in the area.For Lefkas Island, DInSAR analysis (March to September 2003) revealed 56 mm of uplift in the central and western parts and is attributed to the August 2003 earthquake (M_w = 6.3) that occurred offshore to the west. Synthetic DInSAR modelling of the magnitude and extent of deformation is consistent with the seismologically deduced parameters for the ruptured segment along the Lefkas Transform Fault. Subsidence (< 28 mm) along the northern part of the island is attributed to local conditions unrelated to the earthquake. For Zakynthos Island, large-magnitude earthquakes that occurred offshore to the south in October 2005 and April 2006 most likely contributed to the observed deformation as deduced from DGPS measurements for an encompassing period (August 2005 to July 2006). The largest amount of horizontal deformation occurred in the south, where its western part moved in a W–NW direction, while the eastern part moved towards the NE, with magnitudes ranging from 15 to 26 mm. The southern part of the island uplifted a maximum of 65 mm whereas the north subsided from 12 to 28 mm.For Cephallonia Island, DInSAR analysis (1995 to 1998) indicated ground deformation up to 28 mm located in small sections of the island. Further interferometric analysis for the period 2003 to 2004, encompassing the occurrence of the Lefkas earthquake in August 2003, indicated 28 mm of uplift in the northern part, while during the next two years (2004 to 2005), further uplift of at least 56 mm had taken place at the western and northern part of the island.DGPS measurements for the period 2001 to 2006 revealed a clockwise rotation of the island with respect to a centrally located station on Aenos Mt. The horizontal component of deformation generally ranged from 6 to 34 mm, with the largest values at the western and northern parts of the island. Considering the vertical deformation, two periods are distinguished. The first one (2001 to 2003) is consistent with anticipated motions associated with the main geological and tectonic features of the island. The second one (2003 to 2006) has been tentatively attributed to dilatancy in which relatively small uplift (20–40 mm) occurred along the southern and southeastern parts of the island, while larger magnitudes (> 50 mm) happened at the western part (Paliki Peninsula). These large magnitudes of uplift over an extended area (> 50 km), in conjunction with an accelerated Benioff strain determined from the analysis of the seismicity in the broader region, are consistent with dilatancy. This effect commenced some time after 2003 and is probably centered in the area between Zakynthos and Cephallonia. If this interpretation is correct, it may foreshadow the occurrence of a very strong earthquake(s) sometime during 2007 to 2008 in the above designated region.     

Hydrogeological conditions and quality of ground waters in northern Banat,Pannonian basin

Geological relationships, hydrogeology and chemical composition of ground water in northern Banat were studied through the period 2000–2004 using the available background data from published and unpublished sources. Northern Banat is the extreme northeastern part of the Republic of Serbia and a geotectonic part of the vast Pannonian depression. The source of domestic and industrial water supply is only groundwater from artesian and subartesian aquifers of Lower Pleistocene (Q₁¹) and Upper Pleistocene (Pl₃²) sand deposits. The ground water, “peculiar” in chemical composition, is the only source of drinking water in the arid area. A notable variation in the chemical composition of artesian waters within the same geotectonic unit (Pannonian basin), abstracted for municipal water supplies of Kikinda, Novi Knezevac and Djala, has attracted attention of these authors. Our paper attempts to interpret the variation in the chemical composition of ground water and the cause of the variation by the interaction of ground water and rocks forming the aquifers on the case example of the water supply sources for the three mentioned towns. With respect to the depth and lithology of the aquifers, we interpret the varied chemical compositions of waters in the mentioned sources as a consequence of natural factors (geological environment), geological relationships and hydrogeological conditions.     

雷达差分干涉测量及其在地表沉降中的应用与展望

阐述了雷达差分干涉测量(D-InSAR)的基本原理,概括了国内外目前应用比较广泛的D-InSAR模型,针对长时间序列的城市地表沉降监测,应用较多的是基于相干点目标选择,相关的技术包括PSI、SBAS、CRT、CTA。通过多景数据的套合达到消除大气误差相位的目的。进一步总结了相关D-InSAR技术在地表沉降方面的应用进展。相关研究表明,D-InSAR技术能够应用于城市地表沉降监测,并且能够达到较高精度,逐步形成了完善的理论体系和技术处理流程。而且随着技术的发展,监测的时间尺度也在不断扩大、进一步拓展D-InSAR的试验区域。多种数据的结合和补充、方法的有效结合以及与传统的GPS、水准仪测量方法的结合是今后进一步关注的焦点和研究重点。     

井-含水层系统对地下水微动态信息响应能力差异的分析

利用山西地区6口观测井的水位资料,对水震波、前驱波记录次数进行了统计,并对各观测井的潮汐因子、气压效率进行了计算,分析了井-含水层系统对水震波、固体潮、气压、前驱波微动态信息的响应能力,利用井-含水层的特征参数以及含水层的岩性解释了不同观测井对微动态信息响应能力差异的原因。     

Dynamic Response of Footing and Machine with Spring Mounting Base

The effect of the spring mounting cushion inserted in between a machine base and its concrete footing has been examined experimentally by conducting a number of block vibrations tests. The machine was subjected to steady state vertical harmonic loading. Experiments were performed with two different stiffness values of the spring mounting cushion. The employment of the spring mounting cushion, with the stiffness much smaller than that of soil strata, offers a drastic reduction in the resonant displacement amplitudes of the footing. It also results in a significant decrease in the resonant frequency of the foundation. The resonant displacement amplitudes of both the footing and the machine were found to become lower with the smaller stiffness value of the springs. The resonant frequency for the machine base, in all the experiments, was found to be invariably the same as that of the footing.     

Magnetic and ground probing radar measurements for soil pollution mapping in the industrial area of Val Basento (Basilicata Region, Southern Italy): a case study

The joint application of electromagnetic techniques for near-surface exploration is a useful tool for soil pollution monitoring and can also contribute towards describing the spatial distribution of pollutants. The results of a geophysical field survey that was carried out for characterizing the heavy metal and waste disposal soil pollution phenomena in the industrial area of Val Basento (Basilicata region, Southern Italy) are presented here. First, topsoil magnetic susceptibility measurements have been carried out for defining the spatial distribution of superficial pollution phenomena in the investigated area. Second, detailed and integrated measurements based on a high-resolution magnetic mapping and ground probing radar (GPR) profiling have been applied to investigate the subsurface in two industrial areas located in more polluted sites that were identified during the first phase. Our monitoring strategy discloses the way to rapidly define the zone characterized by high pollution levels deriving from chemical industries and traffic emissions and to obtain the way information about the presence of local buried sources of contamination.