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关于地震前兆的判据问题

地震前兆是地震预报的基础,这个基础是由一些个案构成的.应该把地震前兆研究放在地震预报研究之前.对地震前兆的识别需要判据.不能把权威学者的只言片语或者流行的假说当作判别地震前兆的最终凭据,而且目前不具备进行地震前兆统计的基本条件.综合人们以往的认识,识别地震前兆异常有3个自然判据:1)有正常背景;2)非干扰影响;3)与地震相关.其中,与地震相关是核心.可靠的地震前兆判定需要精确的观测资料.对地震前兆判据的研究对制定地震研究规划和观测规范都有指导作用.     

地震前兆仪器实时数据动态与异常报警

利用后台多线程与事件触发技术,实现对地震前兆仪器实时数据的动态展示;通过对实时数据进行长短窗比值与4倍均方差、时均值、日均值等计算,实现实时数据的异常报警功能,并将该功能模块封装成独立控件供用户使用。该控件可实现对全国所有支持实时采集的前兆仪器进行实时数据采集与动态曲线绘制,可实现对各仪器测项实时曲线的浏览观测,具有自动连接、断网重连、网络状态显示、数据异常报警等功能,同时起到仪器监控的目的。     

对流层模型评估及其在GNSS精密单点定位中的应用

以水汽辐射计（WVR）精确测定的天顶方向延迟值作为参考,评估Saastamoinen、GPT2、EGNOS、UNB3M四种常用对流层模型在上海地区的改正精度;并将WVR观测值及以上4种对流层模型计算的对流层延迟值作为真值应用到GNSS精密单点定位（PPP）中,评估其对定位精度的影响。比较发现,GPT2模型的对流层改正精度比其余3种要好,其天顶干延迟（ZHD）的偏差均值与中误差分别为-0.11 cm、±0.75 cm,天顶湿延迟（ZWD）的平均偏差与中误差分别为-2.34 cm、±7.67 cm;和传统的PPP结果相比,采用WVR对流层观测值的定位精度提高了16%。     

Historical aspects of soil erosion in the Mejerda catchment,Tunisia

Abstract

Agricultural use and related water erosion may lead to significant changes in the sedimentological and hydrological characteristics of watersheds, and therefore negative consequences for rural development. This research aimed to put present-day soil erosion of the important Mejerda catchment into a historical context. The catchment of Wadi Mejerda in northern Tunisia has experienced soil erosion due to weather and human impacts for thousands of years. We used historical texts and results from archaeological research that go back to 1000 BC, as well as data collected during the last century. Soil erosion from different types of agricultural landscape management was analysed together with information on the soils' production potential, the hydrographic network and flood frequency. The results showed that water erosion has increased the hydrographic network by 65 km and increased the deltaic plain by as much as 15 km²/century. However, soil productivity has decreased significantly. Moreover, due to in channel sedimentation and river choking, the number of flooding occurrences has multiplied over the last century. Finally, it is shown that water erosion follows a specific cycle of degradation throughout the watershed. These findings should be considered for better water and soil management in the context of semi-arid areas.

Editor Z.W. Kundzewicz

Citation Jebari, S., Berndtsson, R., Lebdi, F., and Bahri, A., 2012. Historical aspects of soil erosion in the Mejerda catchment. Hydrological Sciences Journal, 57 (5), 901–912.     

岷县漳县6.6级地震前区域地壳运动变形背景与断层形变异常特征

利用甘肃岷县漳县6.6级地震区所在的青藏块体东北缘地区的区域水准、GPS、流动重力和跨断层短测线等地形变监测资料,结合地质构造、动力环境和已往的研究结果,分析了不同类型资料反映的震前区域性地壳变形背景、断层形变异常特征和可能的机理.结果认为：（1）岷县漳县6.6级地震前西秦岭、六盘山等构造区不同程度地存在着GPS水平挤压闭锁高应变积累、垂直隆升异常高梯度带和重力升、降差异剧烈变化等中长期背景;（2）震前到震时发震断裂附近及其外围相关构造区域断层形变异常在空间和时间上的起伏波动变化显著,尤其是汶川地震以来的波动变化在一定程度上反映了与本区构造比邻的龙门山断裂带剧烈右旋错动对本区的影响,与本次岷县6.6级地震过程有关;（3）本区有地形变监测资料积累以来缺乏6级以上震例,虽然存在不同程度的中长期形变背景异常,但何时进入短期-短临阶段确实很难把握,需要不断积累总结和探索提高.     

AVO analysis with partial stacking to detect gas anomalies in the GÜEPAJÉ-3D project

We applied analysis AVO with partial stacking to an onshore gas field in order to detect gas at the top of the Ciénaga de Oro formation (FCO), by using seismic gathers of the Güepajé-3D project. The technique was supported by petrophysical analysis of the Ayombe-1 well.The sensitivity of seismic response to changes in the saturating fluid was evaluated by fluid substitution technique in an interval of the Ayombe-1 well. As a result, a class I AVO anomaly at the top of the FCO was observed, even though the gas and water responses were similar. After applying AVO with partial stack technique at the top of FCO, AVO class I anomalies were observed in the Ayombe-1 and Güepajé-1 gas wells and none in the dry Güepajé-3 well. In spite of being reported with gas, the results in the Güepajé-2 well indicated any to an incipient class I anomaly related to a weak seismic response associated to gas.When the technique was applied to the seismic volume of the Güepajé-3D Project, a map of the direct gas indicator was obtained. The map shows a high correlation with the structural surface at top of FCO. Lithic factors such as compaction, cementation and carbonate overlaying the FCO and variable thickness of partial and full saturated layers, may cause anomalies in zones unlikely to contain gas.     

沉降监测数据的非等间距GM(1,1)模型插补应用

科学、准确、及时地分析和预报建筑物的沉降状况,对其施工和运营极为重要,沉降监测的研究成果也是检验设计和施工的重要手段。由于自然环境的多变性、施工现场的复杂性等各种主、客观因素影响,监测数据有时会出现间断,为了分析沉降规律,需要对缺失数据进行插补。考虑到沉降监测非等时间间隔的特点,建立非等间距GM(1,1)模型及优化背景值的GM(1,1)模型,应用于沉降监测缺失资料的插补工作中,取得了较满意的监测间断数据插补值。     

河南渑池铝土矿成矿区地球化学背景

[摘 要]地球化学元素的分布特征反映了元素矿化富集规律。本文在了解矿床地质背景及地球化学性质的基础上,通过对河南渑池地区水系沉积物地球化学测量数据的统计分析,着重研究铝土矿成矿区的地球化学背景,寻找地球化学找矿指标,希望对以后的勘察工作有所借鉴。研究区的铝土矿带位于石炭系本溪组地层中,且本溪组不整合覆盖于奥陶纪地层之上。与上层地层相比,矿层富含Al₂O₃、高场强元素(HSFS),尤其是硼元素。对水系沉积物地球化学数据进行分析,得出反映元素分布形态的地球化学图,结果表明,只有B 元素可以明确反应铝土矿的空间分布位置。矿床点一般沿硼元素高值区边界分布,表明B 元素可以作为河南渑池铝土矿成矿区的地球化学找矿指标。     

基于IRCGA优化的GM(1,1)变形预测方法与应用研究

阐述了引入时间距离权的传统GM(1,1)模型的建模过程以及灰色模型等级的判断方法,深入分析了白化背景参数λ取值对建模精度的影响;同时针对传统λ取值的缺陷,提出使用基于实数编码的改进遗传算法(IRCGA)对其进行优化处理,并用多个工程实例分析验证了优化后的GM(1,1)模型相对传统的灰色模型及其优化模型拟合效果更好,更加贴近真实数据序列。