A graduate student experience with Professor Donald V. Helmberger

A year after the passing of Don Helmberger,it is remarkable how memories of interactions with him over my entire professional career continue to spark affection...     

Magnetotelluric fieldwork adventures in Africa

In her RAS Presidential Address for 2005, Kathryn A Whaler discusses how mapping the electrical resistivity of the subsurface can be used to investigate continental rifting, with examples from Africa.     

定点短水准服务程序

介绍了在Windows操作系统下,用Visual Basic 6.0开发的短水准服务程序,叙述了该程序的主要功能和使用方法.指出,该程序经1 a多的试用,运行稳定,解决了小数进位等问题,取得良好效果.     

The origin of the lunar surface

A mechanism is described how the lunar landscape could have originated by a chain reaction of volcanic eruptions. The mechanism consists of a sequence of three steps; surface solidification and fragmentation, gas formation and crack-wave interactions. A quantitative analysis is presented and it is shown that the volcanic chain reaction was most likely to occur around 10 million years after surface solidification.     

Comprehensive wave climate analysis of the Uruguayan coast

Ocean Dynamics - A detailed analysis of how the wave climate gradually varies from the Atlantic coast to the Rio de la Plata (RDP) estuary coast of Uruguay is undertaken, exploiting a recently...     

1st Ishihara Lecture: An overview of the behavior of pile foundations in liquefiable and non-liquefiable soils during earthquake excitation

The seismic response of a pile foundation is usually analyzed by approximate methods in practice. These methods typically neglect one or more of the important factors that affect seismic response such as inertial interaction, kinematic interaction, seismic pore water pressures, soil nonlinearity, cross stiffness coupling and dynamic pile to pile interaction. A nonlinear 3-D analysis is used to show how all these factors affect pile response, to demonstrate some of the consequences of using various approximate methods and to provide a comprehensive overview of how pile foundations behave during earthquakes in liquefiable and non-liquefiable soils.     

Mars on Earth: soil analogues for future Mars missions

Exploring Mars would be easier if researchers knew more about the properties and behaviour of martian soils. Jeffrey J Marlow, Zita Martins and Mark A Sephton explain how terrestrial analogues could help – especially if we had more of them.     

Outer solar system, Europa, Titan and the possibility of life

A British Interplanetary Society Meeting brought together researchers on the varied environments on planets and moons that might harbour life, reports Julian Hiscox. The Jupiter and Saturn systems are especially dynamic and perhaps hold the key to how life originated on Earth.     

Failure of Marine Deposits and their Redistribution by Sediment Gravity Flows

— SedFlux simulates the fill of sedimentary basins, and can be used to examine the location and attributes of sediment failure on continental margins and the runout of their associated sediment gravity flows. Numerical experiments show how the evolving boundary conditions of sea-level fluctuations, floods, storms, tectonic and other relevant processes control the rate and size of slope instabilities. By tracking deposit properties (pore pressures, grain size, bulk density, porosity), a finite-slope factor-of-safety analysis of marine deposits examines failure potential. A decider routine is used to determine whether the failed material will travel down slope as turbidity current or a debris flow. Examples provided insight into: (i) why fjords dominated by turbidity current deposition often contain debris flow deposits; (ii) how glaciated margins prograde seaward through shallow failures of low yield strength material; and, (iii) how large-scale basin subsidence can control the onset of canyon formation across continental slopes.     

Waves in solar and magnetospheric plasmas

This RAS discussion meeting was arranged with the idea of bringing together solar physicists and magnetospheric physicists, so as to understand better how the two disciplines approach waves, and ultimately to learn from each other. V M Nakariakov, B Roberts and A N Wright report.     

Hands across the sea – and space

A powerful solar flare on 6 December last year produced so much radio noise that GPS signals were significantly affected, according to researchers from Cornell University. This raises the question of how badly such systems would be affected at solar maximum.     

A stochastic distributed model of soil erosion by overland flow

A model has been built to simulate runoff and erosion on slopes of varying form with soil of varying hydraulic conductivity, porosity, storage capacity, and particle size distribution. The model is based on known physical laws and takes into account spatially dependent random variation in the initial conditions of the soil. The rainfall is similarly both random and autocorrelated in space. Detailed results show how runoff is generated as a result of slow conductivity and high water table, how this leads to erosion, the degradation of the land surface, the capture of flow lines, and the development of networks of rills. The last accords well with results from laboratory experiments. Changing the initial conditions produces results that accord with intuition and reality.     

Selected Waste Site Puzzles and Solutions

A dozen case histories of actual waste site puzzles or apparent anomalies, which are initially counterintuitive, are presented. The article emphasizes practical needs for multiple hypotheses, multidisciplinary analyses and open-minded approaches to solve the puzzles. The article recounts how solutions were found to the selected puzzles and provides the solutions.     

CDSN地震事件数据格式的自动变换

在取得ＣＤＳＮ数据之后，所遇到的第一个问题就是数据的格式变换，本文介绍了ＣＤＳＮ数据格式变换的全自动方法，采用Ｃ＿ＦＯＲＭ命令无需提供输入文件名和输出文件名就可以进行格式变换。     

Determination of Horizontal Aquifer Anisotropy with Three Wells

Existing methods for the determination of horizontal aquifer anisotropy by means of pumping tests require a minimum of four wells, one for water withdrawal and three for drawdown observations. This paper shows how the same methods can be used to determine anisotropy with as few as three wells, if at least two of them can be pumped in sequence. A field example is included. A method of analyzing data from more wells than the above minimum, by least squares, is also described.     

Aspects of Modern Raytracing Application Design

Simulating the propagation of seismic energy in an inhomogeneous, possibly anisotropic earth model is a challenging problem, both theoretically and from the computer implementation side. While most publications in the geophysical literature focus on the theory, this paper illustrates how recent advances in computer science can be of great value to researchers who try to create numeric realizations of complex geophysical processes such as seismic raytracing. Modern concepts including object- oriented programming, combined with new and often free-of-charge development tools can significantly improve productivity and flexibility in implementing and exploring new ideas.A variety of issues important in wavefront-construction based raytracing are ad- dressed and it is demonstrated how modern program design may help researchers to more quickly produce better software implementations and free up time to focus on the fundamental theoretical problems.     

网络存储技术在地震数据存储中的应用

随着地震观测和地震科学研究水平的提高,大量宝贵的地震科学数据不断产出.安全有效地存储这些海量地震数据,是目前迫切需要解决的问题.本文简要介绍了网络存储技术的发展和应用,并通过分析地震数据对存储系统的要求,探讨了网络存储技术在地震数据存储中的应用.     

地震前兆数据采集器常见故障分析处理

针对目前地震前兆台站广泛使用的DSC-2和DSC-2A两种型号的数据采集器,对其常见的故障现象及分析处理方法进行深入剖析,就如何在复杂技术系统中确认故障点、数据采集器典型故障进行处理分析,相信对地震前兆台站维护管理人员有一定的指导意义。     

强磁性三度体内部磁化强度的分布

本文讨论稳定磁化场中强磁性三度体内部磁化强度的数值解法。展示了由于退磁作用而造成的不均匀性,并以长方体内一些典型截面为例,较详细地讨论了磁化强度的特征,作了分布图;推导了较均匀磁化体磁化强度分布的近似公式,并计算了一组长方体的视退磁系数。