滇川地下水异常时空转移特征研究

分析研究川滇及邻区地下水异常在中期— 短期— 临震孕震阶段认为, 异常时空转移是地震短临跟踪的一种有效方法。根据中期— 短期— 临震异常井孔数量少— 增多— 减少( 密集) 等变化, 判定地震孕育所处阶段。并用有无区域性异常时空转移等特征预测强震和非强震;用异常时空转移的方向大致估计可能的发震地区;用短临孕震阶段时空转移的明显程度预测发震时间。     

山西忻州奇村水汞观测干扰因素浅析

为进一步明确山西忻州奇村水汞观测过程中存在的干扰因素,分别对硫酸单一试剂、综合试剂、空气湿度、同一个水样多次观测等项进行了试验。试验表明,现用硫酸及其他试剂的汞污染均不明显,对水汞观测构不成于扰;观测室内空气高湿度对水汞观测有一定干扰,且湿度越大,干扰越强,高湿度导致测值大幅突跳;通常所测的水汞含量实为在鼓泡延续时间及空气流量固定不变特定情况下的相对含量,两者的改变会对测值的可比性产生人为干扰。     

用GPS 资料分析渭河盆地及邻近地区地壳运动特征

利用中国地壳运动观测网络工程1999 ~ 2002 年渭河盆地及邻近地区GPS 观测资料, 以及陕西省地震局2001 ~ 2002 年的GPS 观测资料, 研究了渭河盆地及邻近地区地壳运动速度场。结果表明, 渭河盆地及邻区的运动速率有明显的WE 向条带状变化特征, 鄂尔多斯块体南缘呈整体不连续性逆时针旋转运动, 相对鄂尔多斯块体内部的榆林测点, 平均速率约为5.7mm/ a;渭河盆地中部的彬县— 西安— 蓝田一线两侧存在一个左旋剪切带( 东侧) 和右旋剪切带, 左旋剪切带的北部区域与铜川— 泾阳— 临潼— 渭南小震频发区恰好对应;鄂尔多斯块体东南缘临汾盆地东侧, GPS 观测点资料表现出应力集中的迹象, 该区与临汾-韩城地震带也有较好的对应关系。     

水汞观测干扰分析

以试验方法改变日常水汞观测中涉及的化学试剂用量,来分析水汞观测的干扰因素,实验数据表明:硫酸试剂是影响水汞观测结果稳定性的主要因素之一,试剂量与观测结果(汞含量)成正相关关系;而高锰酸钾、氯化亚锡试剂对观测结果几乎没有影响.     

丽江7.0级地震短临异常特征及震源硬化模型

重点讨论了丽江地震短临预报中识别继承性异常、继承性新异常及新异常的形态特征。同时讨论了判断丽江地震进入短临阶段的判据,如中期趋势异常的结束,巨变异常及异常同步转折等特征。最后,在讨论短临异常时空演化的基础上,结合震中区小震活动的异常平静,短临阶段定点前兆由外向震中迁移,异常外围幅度大、数量多等事实,作者提出了新的震源孕青模型——震源硬化模型。按此模型预测,震源区（余震展布区或地表宏观裂缝展布区）在中短期阶段应出现中小地震的异常平静,元或很少有定点前兆异常显示,但当强震孕育发展到破裂成核时——不可逆失稳阶段,某些地震震源区可能会出现明显的宏观破裂,即地表可见喷沙冒水或前震活动。     

水汞观测资料对比分析

通过聊古一井井水中汞量的测定及对比观测试验,找到了影响数据内在质量的干扰因素,提出了浓硫酸、蒸馏水是干扰因素的主要来源,进行空白样的测定是排除干扰,提高观测资料内在质量的重要方法.     

山西忻州奇村水化站水汞观测干扰动态识别方法初探

通过对山西忻州奇村水化站水汞观测水样与空白样测值曲线所含信息的研究,论述了两者产生同步现象的原因及其动态特征,进而提出排除水汞干扰、识别水汞异常的方法。     

通渭温泉水汞映震能力的初步分析

介绍了通渭温泉观测点的基本情况，分析了水汞测量中的干扰因素，对水汞异常与地震的对应关系作了探讨。     

地下水汞观测中干扰因素的实验研究

本文通过对水中汞量测定过程中，可能出现的干扰因素进行了有关试验和讨论，提出了使用的浓硫酸试剂是干扰因素的主要来源，进行水样的空白测定的消除综合干扰，提高观测质量的重要措施。     

地下流体观测环境的评估指标干扰度

地震地下流体观测中的环境干扰问题变得越来越严重, 影响了地震监测预报的效能。 如何评估这种干扰, 更加有效地保护台站的观测环境, 是当前我国地震地下流体观测研究中的重大课题。 经过一年多的研究, 提出了评估地下流体观测环境的技术指标干扰度, 并进一步规定了水位、 水温、 水氡与水汞观测环境的允许干扰度。 干扰度是指各类干扰引起的异常变化幅度与正常时段最大变化幅度的相对百分比值。 允许干扰度的规定, 是依据各类观测得到的地震前兆异常量的大小, 一般采用异常量百分比的最小值。     

复杂地区油气地球物理勘探技术集成

随着我国油气勘探程度的不断提高,勘探难度不断加大.全国油气资源战略选区调查与评价项目历经六年,通过对深水海域、西部复杂山地、西藏高原、南方碳酸盐岩、火山岩覆盖区等几类典型地球物理勘探久攻不克的复杂地区开展地震、重磁电、综合地球物理勘探联合攻关,以及天然地震层析成像攻关实验,取得了长足进步,直接带动获得了一批有价值的油气...     

长江流域近50年降水变化及其对干流洪水的影响

根据我国长江流域气象观测站近42年的资料,分析了整个流域年和季节平均面雨量、暴雨日数和暴雨量的变化特征,以及降水对流域径流和洪水的影响.长江流域年和夏季平均面雨量存在明显的年际和年代变化特征,也表现出比较显著的趋势变化特点.大部分测站年平均面雨量呈增加趋势,夏季和冬季平均面雨量的增加趋势尤其明显;秋季平均面雨量呈显著下降趋势.同时,年和夏季暴雨日数和暴雨量也在较大范围内呈显著增加趋势.长江流域的降水对干流平均流量具有重要影响.1973年、1983年和1998年的洪水主要是由明显高于平均的流域面雨量引起的;长江下游平均流量变化趋势也同流域年平均面雨量、夏季平均面雨量变化趋势基本一致,特别是70年代末以来,下游平均流量和流域面雨量的上升趋势更加明显,并同时在1998年达到最高值.长江流域大的丰水年一般对应El Nino年或El Nino次年,表明E1 Nino对长江较大洪水可能具有一定影响.     

Bioassessment Techniques for Monitoring of Eutrophication and Nutrient Limitation in Coastal Ecosystems

Bioassesment by the use of the macroalga, Ulva lactuca L., was carried out in the Limfjord, Denmark, to assess the significance of nitrogen and phosphorus as limiting factors for primary production during 1985, 1993, 1994 and 1995 and for the detection of changes in eutrophication levels.

Minimum and critical tissue concentrations for nitrogen and phosphorus in macroalgae were identified. The concentrations of nitrogen were generally below the critical concentration level in June–October in 1985, 1993, and 1995 but in 1994 nitrogen was only limiting for primary production in short periods. Only in early spring in 1985 and 1993 were the tissue concentrations of phosphorus below the critical concentration level, whereas in 1994 up to 3–4 months showed phosphorus limited growth, indicating that significant changes in limitation patterns can occur between different years.

It was concluded that the use of biomonitoring techniques is well suited as a bioassessment method for direct detection and for providing a time-integrated measure of nutrient availability in coastal waters, and thus for assessing ecosystem health with regard to eutrophication. It is recommended that biomonitors and the concept of critical tissue concentrations should be used in environmental management and incorporated in future monitoring programmes.     

Non-stationary future return levels for extreme rainfall over Extremadura (southwestern Iberian Peninsula)

Based on a previous study for temperature, a new method for the calculation of non-stationary return levels for extreme rainfall is described and applied to Extremadura, a region of southwestern Spain, using the peaks-over-threshold approach. Both all-days and rainy-days-only datasets were considered and the 20-year return levels expected in 2020 were estimated taking different trends into account: first, for all days, considering a time-dependent threshold and the trend in the scale parameter of the generalized Pareto distribution; and second, for rainy days only, considering how the mean, variance, and number of rainy days evolve. Generally, the changes in mean, variance and number of rainy days can explain the observed trends in extremes, and their extrapolation gives more robust estimations. The results point to a decrease of future return levels in 2020 for spring and winter, but an increase for autumn.     

Emergency planning and mitigation at Vesuvius: A new evidence-based approach

Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.     

传染型余震序列模型震后早期参数特征及其地震学意义

研究中国大陆地区中强地震序列震后早期阶段（震后15天）ETAS模型参数的平均统计特征,据此讨论不同统计条件下的序列衰减及余震激发问题.宏观而言,模型参数b、p、α数值分布较为离散,不同统计条件下模型参数平均值的差异显著性不十分突出.详细对比不同统计条件下模型参数平均值的微小差异,b值随主震震级增大而增大,但b值随不同区域、不同主震断层类型或不同序列类型的变化不明显.p、α具有一定的区域特征,西南、西北p值略低于新疆及华北,表明西南、西北序列衰减相对较慢而新疆、华北序列衰减相对较快,华北α较低而西北α相对最高,意味着尽管华北序列衰减相对较快,但其激发高阶余震的能力却相对强,西北尽管序列衰减较慢,但序列结构单一,激发高阶余震的能力弱.p与主震断层类型关系不明显,即主震破裂性质不是决定序列衰减快慢的主要因素;α与主震断层类型有一定关系,走滑-近走滑型破裂所导致序列的α值最小、斜滑型次之、倾滑-近倾滑型最大,表明走滑-近走滑型序列激发高阶余震的能力最强、逆冲型最弱、斜滑型居中.p、α随主震震级增大而减小,意味着主震震级越高则序列衰减越慢、激发高阶余震的能力越强.不同类型序列p、α有一定差异,主余型序列p最小、孤立型p最大,表明相对而言主余型序列衰减最慢、孤立型序列衰减最快、多震型序列衰减速率居中.孤立型序列与主余型序列α大体一致、大于多震型序列的α值,即多震型序列激发高阶余震的能力相对最强,孤立型及主余型序列则相对较弱.     

我国地震预报研究近十年的发展与展望

简要回顾了我国地震预报的发展过程，并着重对最近10年（尤其是90年代以来）的地震预报研究进展作了较系统的阐述．主要分为：（1）大地震震源区地壳细结构和介质物性的探测研究；（2）地震和前兆数字化观测技术的研制；（3）地震短临预报方法及其判据、指标的研究；（4）地震序列类型和震后趋势早期应用判断方法及其指标的研究；（5）华北北部地震短临预报方法、前兆综合解释模型与短临预报综合判别系统的研究；（6）地震预报新技术、新方法的探索；（7）地震中长期预报研究及我国近期（10年左右尺度）地震重点监视防御区的确定；（8）板内地震孕育发生的物理模型及前兆场物理解释的探索研究．最后还对我国地震预报的未来发展进行了展望．     

首都减灾圈的思考与建议

首都减灾圈,系首都减轻自然灾害预测防治圈。1991年12月20—21日在北京召开了《首都圈自然灾害及其减灾对策研讨会》。本文根据这次会议所提供的材料,在从整体上实现减灾的思想指导下,就首都减灾圈的“成灾背景”、“首都减灾圈的组成”、“首都减灾圈的灾害预测与防治状况”、“首都减灾圈的灾害关联性分析”、“首都减灾圈的减灾实效预估”和“首都减灾圈的减灾对策与实施”等六个带有共同性的问题,进行了讨论。供制定首都圈减灾方案时参考。     

Concentrations and transport of trace metals in the St. Lawrence River

Samples of raw water were collected in the St. Lawrence River during six sampling trips from August 1990 to April 1992. Water samples were analyzed for both dissolved and particulate phases for five trace metals. Partition coefficients (Kd) and metal fluxes were calculated in order to determine metal transport. A mass balance equation was used for the determination of the major metal sources to the St. Lawrence River and an estimation of metal loadings to the estuary was made. Average dissolved metal concentrations were found to be Cd 10 ng/L, Co 74 ng/L, Cu 64 ng/L, Fe 69 µg/L and Mn 700 ng/L. Particulate concentrations were (in µg/g) 1.68 for Cd, 31 for Co, 73 for Cu, 25 mg/g for Fe and 1.69 mg/g for Mn. Co, Fe and Mn were transported essentially in the particulate phase while Cd and Cu were predominantly found in the dissolved phase at 56% and 48% of the total metal concentration respectively. Log Kd values varied from 5.1 (for Cu) to 6.8 (for Mn). In the dissolved phase the major sources were found to be the Great Lakes and the Ottawa River whereas in the particulate phase Québec tributaries appear to be the most important. Industrial inputs are quite important in both the dissolved and the particulate phases for Cd, whereas other sources are very variable, especially for the dissolved phase.     

桥梁抗震设计规范的现状与发展趋势

本文对世界主要桥梁结构抗震设计规范的现状进行了较为详细的对比,指出我国现行《公路工程抗震设计规范》中存在的一些缺点。本文还对目前国际上桥梁结构抗震设计规范的发展动向进行了总结,提出了修订我国新《城市桥梁抗震设计规范》的一些意见。