E‐tracers: Development of a low cost wireless technique for exploring sub‐surface hydrological systems

This briefing describes the first deployment of a new electronic tracer (E‐tracer) for obtaining along‐flowpath measurements in subsurface hydrological systems. These low‐cost, wireless sensor platforms were deployed into moulins on the Greenland Ice Sheet. After descending into the moulin, the tracers travelled through the subglacial drainage system before emerging at the glacier portal. They are capable of collecting along‐flowpath data from the point of injection until detection. The E‐tracers emit a radio frequency signal, which enables sensor identification, location and recovery from the proglacial plain. The second generation of prototype E‐tracers recorded water pressure, but the robust sensor design provides a versatile platform for measuring a range of parameters, including temperature and electrical conductivity, in hydrological environments that are challenging to monitor using tethered sensors. Copyright © 2012 John Wiley & Sons, Ltd.     

论地方地震工作在短临预报中的作用

地方地震工作是我国地震工作的重要组成部分,在短临预报的监测、震情的动态跟踪、前兆观测方法的探索以及各种前兆信息的获取和识别方面。具有与专业地震队伍不同的特点、优势和不可替代的作用。地方地震工作还具有观测手段比较科学,布局比较合理,覆盖面广,接近震区,可补充专业台网不足等特点,因此已经成为整个地震系统中捕捉短临异常、实施短临预报不可缺少的一个重要组成部分。同专业地震队伍一起密切配合,为综合防御和最大程度减轻地震灾害发挥了重要作用。     

和静5.2级地震单台地震学预报方法的跟踪研究

以1991年6月6日和静5.2级地震为例,较为系统地分析研究了部分单台地震预报的地震学方法的异常变化过程。结果表明,利用单台地震资料进行跟踪式预报的实用化研究,可以为地震预报决策提供有效的依据。     

Seasonal Variation of Stationary and Low-Frequency Rossby Wave Rays

The wave rays and their seasonal variation of stationary and low－frequency Rossby waves are studied by using the Runge-Kutta scheme. The results show that for stationary waves the rays can reach lower latitudes in winter, and are limited in higher latitudes in summer. The main differences between the stationary and low-frequency wave rays are that low-frequency waves can propagate across the equator and the easterlies will not be an obstacle on their propagation. It explained to some extent the interaction of disturbances between the Northern and Southern Hemi-spheres. The lower wave frequencies and the stronger easterly flow are, the more difficult low-frequency waves will be to propagate across the equator. The waves with 20-day period are easier to propagate across the equator than that with 50-day period. The winter is the most favorable season for low-frequency waves to propagate into another hem-isphere.     

地电学预报地震的综合跟踪方法

在本文中叙述了地震地电学方法判断地震活动趋势的８条指标：１．电性前兆出现的部位；２．地电年变化背景场；３．地震地电阻率ρｓ的早期下降变化；４．中期平稳波动变化；５．短期加速下降变化；６．临震快速回返变化；７．电性多参数无纲前兆；８△．Ｔ的对数与Ｍ之间的统计关系。     

Ray parameters of diffracted long period P and S waves and the velocities at the base of the mantle

The derivation of P and S velocities at the core-mantle boundary (CMB) from long-period diffracted waves by the use of the simple ray-theoretical formulav _CMB=r _c /p (v _CMB=velocity at the CMB;r _c =core radius;p=ray parameter) yields apparent velocity values which differ from the true velocities. Using a dominant period of about 20 sec for calculating theoretical seismograms, we found a linear relation between the apparent velocity and the average velocity in a transition zone at the base of the mantle with fixed velocity on top.The ray parameters determined from long-period earthquake data are found to be 4.540±0.035 and 8.427±0.072 sec/deg for P_diff and S_diff, respectively. These values yield apparent velocities of 13.378±0.103 for P and 7.207±0.062 km/sec for S waves. By means of the theoretical relation between apparent and average velocity and under the assumption of linear variation of velocity with depth, one can invert the apparent velocities into true CMB velocities of 13.736±0.170 and 7.320±0.124 km/sec. These results imply positive velocity gradients at the base of the mantle and hence no significant departures from adiabaticity and homogeneity.Contribution No. 211 of the Geophysical Institute, University of Karlsruhe.     

青藏高原及邻区新生代火山岩Sr-Nd-Pb同位素特征

笔者在综合分析最近十多年来的Sr、Nd、Pb同位素资料基础上,重点研究了青藏高原及邻区新生代火山岩岩浆源区在时空上的变化规律。结果表明：①冈底斯中段火山岩的岩浆源区逐渐从普通地幔向EMⅡ方向演化;西段晚期火山岩源区的演化方向为俯冲带壳幔混合源→造山带上地壳源→下地壳源。②西羌塘岩浆源区主要为不具富集或亏损的幔源物质;囊谦盆地、大理海东火山岩源区较深,为大洋型软流圈地幔 消减组分混合源;藏北羊湖、雄鹰台—鲸鱼湖、西昆仑以及北羌塘巴毛穷宗火山岩的岩浆源区为EMⅡ;鱼鳞山超钾质火山岩为经历了大陆地壳物质强烈交代作用的EMⅡ型岩浆源区;西秦岭火山岩源于亏损地幔,腾冲新生代火山岩源区为受到地壳物质交代的EMⅡ。③西羌塘、可可西里、西昆仑和腾冲新生代火山岩具两种演化趋势——鱼鳞山、普鲁、雄鹰台—鲸鱼湖岩区和腾冲火山群向EMⅡ方向演化,而泉水沟、黑石北湖、阿什库勒则分别沿0Ma的地幔—上地壳混合线方向演化。④青藏高原及邻区新生代火山岩至少存在4种不同的岩浆源区。     

Surface water/groundwater interaction in the Piora Aquifer,Switzerland: evidence from dye tracing tests

Results of seven dye tracing tests done from 1993–1997 to investigate the extent to which lakes and surface water interact with the underlying Triassic Piora Aquifer, Switzerland, are reported here. Two of the dye tracing tests showed that groundwater flows in the Piora Aquifer from the Piora Valley to springs in the adjacent Santa Maria Valley, and even further east to the di Campo Valley considerably outside of the Piora Valley surface water divide. Lake Ritom located in the Piora Valley loses water only to the Canaria Valley outside of the lake's surface-water watershed at the lake's western margin when lake levels are above 1,835 m above sea level. Dye tracing tests show that a major sinkhole in the Piora Valley, Calderoni Sinkhole, is located precisely on the water divide where subsurface flow in the Piora Valley and surface water diverge and move in opposite directions. The dye tracing results also showed no hydraulic connection between surface water in the Piora Valley and the famous Pertusio Spring, located in the upper Santa Maria Valley. Only a small amount of dye from the two dye tracing tests done in 1993 and 1997 entered an exploratory gallery built to test the viability of the AlpTransit tunnel, being built in competent rock under the Triassic Piora Aquifer, effectively perched above. Electronic Publication