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- Volume 24, Issue 8, 2006
First Break - Volume 24, Issue 8, 2006
Volume 24, Issue 8, 2006
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How one man warmed to a career in geoscience
By A. McBarnetProfile by Andrew McBarnet of Prof John Reynolds, an acknowledged world authority on glacial hazard assessment and mitigation (see Special Topic p. 61), but also a vocal advocate of the value of geoscience with a remarkable career to prove it. If you’re searching for an example of how to make geoscience relevant to today’s generation of maths and science shy students, look no further than Prof John Reynolds. His career has been devoted to geoscience across a broad range of activities, but is now increasingly focused on affecting positive change for communities around the world through the application of environmental geoscience. In addition, he is a passionate advocate for his profession, as a public speaker, an educator, and indeed as author of the standard textbook on applied and environmental geophysics for university students. From his small consultancy base in Mold, North Wales he has sought the ear of governments and international agencies in an effort to alert them to the potentially catastrophic dangers posed by natural phenomena such as glacial hazards and earthquakes. For example, glacial lakes in the Himalayas in countries such as Nepal, Bhutan, India, Pakistan, China, Tibet, and Kyrgyzstan are expanding rapidly as a result of global warming. Some of the lakes are inherently unstable, because their dams can be ice cored and consist of unconsolidated rock debris. Just what can happen was shown in 1954 in Tibet when an uncontrolled rise in the water level led to the collapse of a dam which poured an estimated 300,000 m3 of rock and water without warning in a 40 m high flood surge into China. This so called glacial lake outburst flood (GLOF) travelled over 120 km destroying the town of Gyanze and killing thousand of people. Reynolds points out that since the 1950s temperatures have risen significantly so that so that glaciers are retreating at an average of 20-50 m per year. (The science of glacial hazard assessment is discussed in Reynolds’ article in this issue on p. 61)
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World energy supplies come at a cost
First Break presents a snapshot version of the BP Statistical Review of Energy 2006, the 55th in the series, covering data on worldwide energy production and consumption up to the end of 2005. BP chief economist Peter Davies said at the launch of the BP Statistical Review of World Energy 2006 that supply availability in 2005 continued, but at the cost of high prices. ‘Market adjustments are beginning and will continue. There has been a price effect already with coal and gas prices falling and oil consumption growth slowing sharply and inventories rising.’ Energy developments Crude oil, natural gas and coal prices all hit record (nominal) levels in 2005. Combined with a modest reduction in global economic growth, this resulted in a slowdown in energy consumption growth. World primary energy consumption increased by 2.7% in 2005, below the previous year’s strong growth of 4.4% but still above the 10 year average. Growth slowed from 2004 in every region and for every fuel. The strongest increase was again in the Asia Pacific region, which rose by 5.8%, while North America once more recorded the weakest growth at 0.3%. US consumption fell slightly, while China accounted for more than half of global energy consumption growth.
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Role of geophysics in glacial hazard assessment
More LessJohn M. Reynolds of Reynolds Geo-Sciences, explains how geophysical methods can play an important role in understanding glacial hazards and their little discussed but potentially disastrous threat to communities in the world’s mountainous regions and beyond. Climate change, whatever its causes, is resulting in the recession of glaciers (e.g. IPCC, 2001) and the development of glacial lakes in high mountain chains across the world. As time progresses, more lakes are forming and lake volumes are increasing. In parallel with this, catastrophic failure of terminal moraines damming such lakes is occurring increasingly frequently especially in the Himalayas, with recent examples also in the Alps and the North American Rockies, among other areas. In a typical glacial lake outburst flood (GLOF), some 15-50 million m3 of water and debris can be disgorged downstream causing widespread damage and destruction, in some cases for hundreds of kilometres. Peak discharges can exceed 10,000 m³/sec down river channels more often used to dealing with less than a few hundred m³/sec even during peak monsoon flows. Flood waves tens of metres high can travel at speeds of tens of kilometres per hour, with flood durations lasting from one to several days. The effects of such events can last for decades.
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Near surface investigations over a disposal site for blast-furnace slag using Rayleigh surface waves
Authors D. Orlowsky, C. Witte and B. LehmannDirk Orlowsky, Christoph Witte, and Bodo Lehmann, DMT, Germany describe a relatively simple use of near-surface seismic to identify potential instability at a building site formerly used for blast furnace slag. Surface and channel waves have been used for investigating lateral subsurface variations in the Earth for many years. Surface waves propagate along the Earth’s surface and their amplitudes decay with depth. Due to this amplitude decay in one space dimension, the propagation of surface waves is restricted to two space dimensions and the energy is effectively confined to the Earth’s surface. This leads to signal signatures with strong amplitudes at the surface and surface waves are therefore very sensitive to changes of the near-surface structure. Two different kinds of surface waves are observed in elastic media, Love waves and Rayleigh waves, characterized by different particle polarization. Channel waves, which occur in low velocity layers, are very similar to surface waves. Knowledge about surface and channel waves in the past four decades has led to the development of the in-seam seismic method (ISS-method) (Dresden & Ruter, 1994) for the detection of seam disturbances. In seismology, surface waves have been used over many decades for the investigation of the Earth’s crust and the upper mantel structure (Seidl & Muller, 1997; Keilis-Borok, 1989; Nakanishi, 1993). However, just a few years ago, geophysicists started to adapt in seam seismic methods and to develop new routine techniques (Park, Miller, & Xia, 1999) for the purpose of investigating the near-surface structure of the Earth with surface waves. This has led to the development of the surface wave seismic method (SWS-method) for near-surface investigations. In this context, the expression ‘near-surface’ denotes a range from the surface to a maximum depth of about 20 m.
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Amplified geochemical imaging: an enhanced view to optimize outcomes
More LessHarry S. Anderson of W. L. Gore & Associates describes the benefits of amplified geochemical imaging in a variety of context including environmental and oil and gas applications. Before surgeons begin any delicate operation, they use state-of–the-art imaging to afford an enhanced view into the human body. Without question, the accuracy and detail of a CAT scan or MRI increases their chance of a successful surgical outcome. With a resource so precious, who wouldn’t use the best technology? Likewise today’s earth scientists have sophisticated imaging tools available that provide them with the enhanced view they need to focus their efforts, save time and money, and generate more reserves and profits. 3D seismic imaging is the tool we often think of first in petroleum exploration but recent advances have made possible a complementary technique: amplified geochemical imaging. This advanced geoscience tool is used in diverse applications such as environmental site assessment and pipeline integrity management, as well as petroleum and mineral exploration. Since 1930, earth scientists have used surface geochemical techniques to explore for hydrocarbons. These techniques look for the effects of minute levels of hydrocarbons that migrate through the imperfect seals that cover every reservoir and migrate either as macroseepage via faults or as microseepage vertically through the reservoir overburden. (Klusman, 1993, Coleman et al., 1977) Some of these early techniques were crude and included soil analysis, active soil gas analysis, iodine mapping, and microbial counting. Unfortunately, exploration results using these early geochemical techniques were often disappointing. This is a direct result of several fundamental factors: - Inability of the sampling method to cope with heterogeneous soil characteristics including permeability, moisture, and organic content - Heavy losses in compounds due to sampling techniques (Hewitt and Lukash, 1996) - Monitoring indirect effects (like microbes or iodine) rather than direct effects - Poor sensitivity (ppm rather than ppb or ppt) - Severely limited set of compounds not representative of the target (C1-C6 only) - Failure to use statistical tools to clearly differentiate noise from signal
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Hydrocarbon potential of Somaliland
By M.Y. AliSomaliland (Northern Somalia) is situated on the northern side of the Horn of Africa with the Gulf of Aden to the north, Somalia to the east, Ethiopia to the south and west, and Djibouti to the north-west (Fig.1). The morphology of the country is typical of areas in extension, with basins and mountains of up to 2000 m. There is little folding, but much normal faulting, some of which has very great throws. These strong vertical movements have controlled the accommodation space available for sediment deposition since the Lower Jurassic. To date there have only been 21 wells drilled in Somaliland (19 onshore and two offshore), many of which were only stratigraphic tests (Fig. 2). In fact few of the wells evaluated the hydrocarbon potential of the country and the type of prospects in the drilled basins. In addition, modern seismic reflection surveying has had very limited application in Somaliland. Therefore, many prospective petroleum systems in the onshore and offshore regions of the country remain relatively unexplored. In this paper, seismic, well, and outcrop data have been used to determine the petroleum systems of Somaliland. These data demonstrate that the country has favourable stratigraphy, structure, oil shows, and hydrocarbon source rocks. In addition, the results show that the Upper Jurassic and Cretaceous units, and possibly Oligocene-Miocene units, show potential for hydrocarbon generation. Traps are provided by rollover anticlines associated with listric growth faults and rotated basement faults which are controlled by Upper Jurassic to Lower Cretaceous tensional stresses.
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Delft Internet-based introduction course on reflection processing with Matlab
Authors D.W. van der Burg, G.G. Drijkoningen and G.F. MargraveIn earth sciences nowadays, interdisciplinary teaching has become a common theme. Reflection seismology is an important course in such a curriculum, since it is such a powerful tool to unravel the mysteries in the Earth. From a multi-disciplinary earth scientist’s point of view, an introductory course on reflection seismology should convey the concept of the method. To support this, exercises on the computer are very much needed, if not indispensable. When choosing a certain computer environment for the supporting exercises, the main goal should be that the student (often not a geophysicist!) has to stay focused on trying to understand the seismic method, rather than understanding the software or its environment. Combined with the fact that many students do not have a sound basis in Unix (any more), Matlab becomes a very good option as the environment for an introduction on reflection seismology. In this article, we will first elaborate on the specific advantages and drawbacks when working with Matlab as a processing environment, with the aim of introducing reflection seismics to the multi-disciplinary earth science student. Then, we will describe what is offered by the Delft Internet-based course. To give insight also into the student’s perspective, we have inserted in several places in the article reactions from our students to the course, for example, ‘instructive experience for the clarification of the objectives of geophysics’, and ‘nice to see theory in practice’.
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Volumes & issues
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)