共查询到20条相似文献，搜索用时 46 毫秒
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萧山-球川断裂是浙江地区1条大规模的北东向断裂，在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法，对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚，对地貌的控制作用较为明显，对山前的第四系发育有明显影响。通过对断裂露头剖面的分析，认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽，结合ESR年龄测定，判定该断裂在第四纪早、中期有过活动，但未断错上覆中更新统上部地层，其最新活动时代为早、中更新世。 相似文献
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Mostafa Baniasadi Mohammad Reza Zare' Mehrjordi Hossein Mehrabi Boshrabadi Hamid Reza Mirzaei Khalilabad Abbas Rezaei Estakhrooye 《Ground water》2020,58(4):560-570
In recent decades, increased extraction of groundwater for human and agriculture consumption has led to a substantial drop in groundwater level in large areas of across the world. Declining groundwater levels is a serious problem in itself and has multiple economic, social, cultural, political, security-related, and environmental externalities. The negative economic-environmental externalities of overextraction of groundwater in the Orzouiyeh plain in the Kerman Province, Iran, were evaluated using methods such as replacement cost, production function, market prices, shadow price, and the value of the input marginal product. After evaluating externalities, the Positive Mathematical Programming method was used to evaluate different water policies to reduce the consumption of groundwater. The total economic losses due to the externalities were calculated to equal 2.8 U.S. million dollars. The damages caused by environmental externalities were calculated to equal 436.1 U.S. million dollars. The results related to the positive planning model show that the best policy among different options, such as deficit irrigation policy or combined policies, involves implementation of pressurized irrigation systems. 相似文献
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Yu. O. Kuzmin 《Izvestiya Physics of the Solid Earth》2013,49(5):626-642
The results of analyzing the long (20–50 years) time series of geodetic observations carried out in the regions with enhanced seismotectonic activity (Kopet Dag, Kamchatka, and California) are presented. It is established that recent vertical and horizontal displacements in the fault zones estimated by instrumental geodetic observations with increased spatiotemporal resolution indicate that the deformations in the fault zones paradoxically deviate from the movements inherited from the previous geological epochs. The paradoxes of high and low deformation rates in recent geodynamics lie in the reliably established empirical fact that extremely high local deformation rates (up to 10?5 per annum and higher) exist in the fault zones in the setting of weak regional deformations, whose annual rates are by two to three orders of magnitude lower. Very low annual average rates of relative horizontal deformations, which only measure 3–5 amplitudes of tidal deformations of the solid Earth, are revealed in the seismically active regions of Kopet Dag and Kamchatka as well as in the San Andreas Fault Zone in northern California. The fault-block dilemma arising in the interpretation of the observations of recent fault geodynamics is formulated. Either the role of active element, which forms the present anomalous deformations, is played by a block, while a fault plays the role of the passive element, or the fault zone itself is a source of anomalous movements, while the blocks are passive elements (hosting medium). It is shown that paradoxes of low and high deformation rates vanish if we assume that the recent anomalous geodynamics is formed by parametric excitation of the deformation processes in the fault zones in the conditions of quasi-static loading. 相似文献
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Summary It has been proved that the formulae for determining the horizontal co-ordinates of the centre of gravity, derived by Gamburtsev in 1938 and adopted in many textbooks of gravimetry and other works, are not accurate. A method of estimating the co-ordinates of the centre of gravity of a disturbing body has been elaborated under the assumption that just the values of the vertical gradient of the disturbing gravitational potential in the xOy-plane are known. 相似文献
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Microzonation of the city of Basel 总被引：1，自引：0，他引：1
During the past centuries, the city of Basel has suffered damage caused by earthquakes. One extraordinary event described in historical documents is the strong earthquake which occurred in 1356. The 1356 event, one of the strongest earthquakes in northwest-Europe, was obviously much stronger than the low-magnitude earthquakes observed in the area during this century. Even though the present seismicity in the Basel area is low, strong earthquakes have to be expected due to the city's geographical location close to the northern boundary of the African-European convergence zone, at the southern end of the Rhinegraben. A crucial step towards preparedness for future events and mitigation of earthquake risk involves a microzonation study of the city. The study is carried out in three steps: (1) a detailed mapping of the geology and geotechnical properties of the area, (2) measurement, interpretation and modelling of ambient noise data, and (3) numerical modelling of expected ground motions during earthquakes. A qualitative microzonation of the centre of Basel is presented, and it is discussed by comparing it to the historically reported damage of the 1356 earthquake. 相似文献
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本文在理论上研究了对齐误差对测试地震计自噪声的影响。指出对齐误差影响到2台仪器记录间的计算互功率谱密度, 进而影响到被测仪器记录间相干函数计算, 最终影响到被测仪器的自噪声计算。发现当存在对齐误差时, 在信噪比较高频段计算得到的自噪声水平比仪器的实际自噪声水平要高, 在一般的实际测试中可能高20 dB以上。为了消除对齐误差对自噪声测试的影响, 提出通过投影逆变换把观测记录变换到标准坐标系下, 再用变换后的观测记录来计算地震计自噪声。给出了基于以上思路和传感参数对比测试方法的地震计自噪声计算处理流程, 合成数据、 实际测试数据的处理检验计算结果表明, 本文方法可以有效克服地震计自噪声测试中对齐误差的影响。 相似文献
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P.A. Read K.J. Anderson J.E. Matthews P.G. Watson M.C. Halliday G.M. Shiells 《Marine pollution bulletin》1983,14(1):12-16
A long-term benthic study has been undertaken in the Firth of Forth to assess the environmental impact of a new sewage treatment scheme for the city of Edinburgh. The Sewage Scheme reduces the suspended solids content of the liquid effluent by approximately 60% and achieves a lowering of the concentration of materials in solution through more efficient dilution and dispersion. Marked changes in the intertidal benthic flora and fauna have been recorded along the Edinburgh coastal zone. These changes have been apparent as the decline and disappearance of populations of certain pollution indicator species and the appearance and establishment of several species previously unrecorded along the more polluted parts of the Edinburgh shoreline. Study of the sublittoral benthos has shown no deleterious effect arising from the new effluent outfall, although there does appear to be some enhancement of the fauna in the area. 相似文献
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研究了华东地区１５个地震序列的振幅比、初动方向和初动半周期资料。得到：大震（主余型序列中的主震或震群型序列中最大地震）前后的Ｐ波初动方向，除人们熟知的由优势分布转化为紊乱外，还有可能呈优势分布，优势方向改变的特征。余震序列的Ｐ波初动方向和振幅比特征可能有助于预测强余震。初动半周期特征可能用于区别的前震和余震。 相似文献
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Xuan Tinh Nguyen Minh Thanh Tran Hitoshi Tanaka Trung Viet Nguyen Yuta Mitobe Cong Dien Duong 《国际泥沙研究》2021,36(1):1-16
The current study presents the effects of seasonal variations in the depth-of-closure(Dc)on shoreline evolution using a numerical,one-line shoreline model.Beach erosion of the southern beach of the Nha Trang Coast,which is located in south central of Vietnam,is selected as the study area.This study area is immensely influenced by the tropical monsoon climate that has a clear pattern of large waves in the northeast monsoon season and calm waves in the non-monsoon season.The analysis of the long-term measured shoreline variations from a video-camera system has found a strong correlation of these variations to the monsoon-dominated wave characteristics in the Nha Trang Bay.Therefore,a new approach for determining the depth-of-closure with consideration of the seasonal wave climate changes is purposed in the current study.By implementing this new approach into a numerical,one-line shoreline model,it is found that the seasonal variations of Dc appear to better describe the periodical shoreline evolution due to the monsoon-dominated wave characteristics for the Nha Trang Coast.Such important findings are considered to commonly apply for monsoon-dominated coastal regions in general.These findings are useful information not only for scientific readers but also for the coastal authorities and managers in order to make better countermeasure plans against this kind of erosion mechanism in the future. 相似文献
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The possibilities of the remote estimation of the distribution character of the rock natural remanent magnetization in the zones of geomagnetic field reversal are considered. The Faraday effect—rotation of the signal polarization plane in the magnetic field—is used for this purpose in the process of radar impulse sounding of the magnetic field. 相似文献
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An electric furnace with oxygen-fugacity control was constructed. Oxygen partial pressure inside the furnace is controlled by flowing H2 and CO2 gas mixtures in different ratios. The system is set up inside a three-layer permalloy shield and a solenoid coil to produce an axial magnetic field. Oxygen fugacities are directly measured by an yttriadoped zirconia probe. The difference between the predicted and measured values of fugacities was small at 1,200°C, but a substantial discrepancy was observed at 780°C. Thermoremanent magnetization (TRM) was produced in various gas mixtures by heating the samples of recent basaltic lavas of Oshima (Japan) and Hawaii to 600 or 800°C for 1 h and cooling in a 0.4-Oe field. In general, the TRM is larger when produced in an oxidizing atmosphere and smaller in a reducing atmosphere. Alternating field demagnetization shows that the coercivity is also increased (decreased) when the TRM is acquired in oxidizing (reducing) conditions. However, these properties depend also on the previous heat treatments of the samples. 相似文献
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目的：探讨韧带样纤维瘤的影像学表现。方法：结合文献分析4例经术后病理证实的韧带样纤维瘤的病理、临床及影像学表现。结果：本组4例发病部位分别为腹腔、腹壁、胸壁及腋窝和股骨下段。典型的韧带样纤维瘤表现为较均质的单发病灶,CT平扫比相邻软组织密度稍高或相等,在MRI上可因肿瘤内成分不同而引起T2WI信号的变化。增强后有轻度、... 相似文献
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地震工程试验联网最新进展 总被引：5，自引：2，他引：5
郭迅 《地震工程与工程振动》2006,26(4):37-41
地震工程试验联网(NEES)是新世纪地震工程学科最重要的事件。由美国国家自然科学基金会牵头,全美15家主要的地震工程研究单位共同实施一项旨在调动全部优势资源进行复杂结构体系的地震响应协同试验研究计划。该计划从1999年开始,将于2014年全部完成,目前多数成员单位进入设备安装调试阶段,有些单位利用新装备实现了某些利用传统手段无法完成的试验任务。建议工程力学研究所燕郊的结构实验室直接按照加入NEES的标准进行硬件配置和软件开发,使硬件的数量和技术指标满足NEES要求;使软件与硬件配套,实现与NEES联网,可远程快速通讯,实时监控,实时数值模拟计算,实现显式、隐式和显隐混合算法伪动力试验以及具有位移控制、力控制、位移和力混合控制功能。 相似文献
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本文提出我国北方含水量高的低洼地段公路工程中路基填方铺设方法,重点研究了材料配合比不确定、工程地质条件复杂、充填施工质量不易控制等问题,进行二灰土击实与压缩性能的试验研究,得出了石灰、粉煤灰和土3种充填材料的配合比,并针对工程特点,提出了确保施工质量的措施。室内试验及现场施工均取得了较满意的结果,该研究为公路路基填方提供了可借鉴的经验。 相似文献
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目的:分析淋巴结结核的CT和MRI表现特点，并与病理学对照，探讨两种检查方法的应用价值。方法:回顾性分析2010年1月至2014年12月间34例经手术、穿刺病理或临床证实为淋巴结结核患者的CT或MRI影像学资料，分别从生长方式（融合/非融合）、边缘（光滑/欠光滑）、境界（清晰/欠清晰）、密度及信号、增强后强化方式（均匀/不均匀/环形规则/环形不规则）这5个方面对所受累淋巴结进行分析。结果:34例患者中共累及223枚淋巴结，其中颈部淋巴结67.7%，纵隔内淋巴结27.7%，肺门淋巴1.8%，肺内淋巴结0.5%，腹腔淋巴结0.5%，腹膜后淋巴结1.8%。所有受累淋巴结中，8.5%呈融合性生长，83.9%形态规则，79.4%边缘光滑。CT上发现的171枚病变淋巴结以等密度较多（53.8%）、低密度次之（43.3%），MRI上发现的66枚病变淋巴结中98.5%为等T1长T2信号。所有CT及MRI观察到的病变淋巴结中，除57%的病灶密度或信号均匀外，仅伴钙化的为12.6%，仅伴部分坏死的26.9%，另外有3.6%同时伴钙化及坏死；增强扫描的204个病变淋巴结中，1%钙化显著、未见明显强化，38.7%均匀强化，伴坏死者内见不强化的低密度区，11.3%呈环形规则强化（均位于颈部），8.3%环形不规则强化（纵隔内82.4%），5.9%可见病变淋巴结内有分隔样强化（均位于颈部）。结论:CT与MRI对于淋巴结结核具有重要诊断价值，两者均能清晰显示病变部位、形态以及边缘情况，MRI对于病变边缘及周围情况显示较CT更明确，尤其是增强后，对于包膜及邻近组织受累情况的显示也更加敏感。 相似文献