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John m 2003 field geophysics third edition john wiley

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John, M. (2003) Field Geophysics (Third Edition). John Wiley and Sons Ltd. England, 249pp
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36 McCann, D.M., Fenning, P. and Cripps, J. (Eds) (1995) Modern Geophysics in Engineering Geology, Engineering Group of the Geological Society, London, 519 pp. Mussett, A.E. and Khan, M.A. (2000) Looking into the Earth: An Introduction to Geological Geophysics, Cambridge University Press, Cambridge, 470 pp. Parasnis, D.S. (1996) Principles of Applied Geophysics (Fifth Edition Chapman & Hall, London, 456 pp. Reynolds, J.M. (1997) An Introduction to Applied and Environmental Geophysics, Wiley, Chichester, 796 pp. Sharma, P.V. (1997) Environmental and Engineering Geophysics, Cambridge University Press, Cambridge, 475 pp. Telford, W.M., Geldart, L.P., Sheriff, R.E. and Keys, D.A. (1990) Applied Geophysics (Second Edition), Cambridge University Press, Cambridge, 770 pp. Whitely, R.J. (Ed.) (1981) Geophysical Case Study of the Woodlawn Orebody, New South Wales, Australia, Pergamon Press, Oxford, 588 pp. Hawkins, L.V. (1961) The reciprocal method of routine shallow seismic refraction investigations. Geophysics, 26 , 806–19.
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37 Unit 2 Reflection Surveys 1.0 Introduction Reflected waves are never first arrivals, so clear-cut reflection events are seldom seen. Oil-industry techniques for improving signal-to-noise ratios can be used for shallow work and simple versions of the programs used are incorporated in the software supplied with the latest generation of 12- and 24- channel seismographs. 2.0 Objectives At the end of the unit, readers should be able to (i) Give a descriptive treatment of the more important aspects, concentrating on the developing fundamental of reflection surveys. (ii) Know that reflection survey techniques are therefore widely used in oil industry for exploring oil. 3.0 Main Contents 3.1 Spread lengths The distance from the source to the nearest geophone in a shallow reflection survey is usually dictated by the strength of the source (and the need to protect the geophone) and may be as little as 2 m when a hammer is being used. Even with explosives or heavy weight drops, minimum offsets of more than about 10 m are unusual when observing shallow reflections. A reflection spread can be much shorter than a refraction spread used to probe to similar depths, but with powerful sources and multi-channel recording, the furthest geophone may be more than 100 m from the source. The optimum spread length can be determined only by experiment, since the most important factors are the arrival times of the noise trains associated with the direct wave and any strong refracted waves. Field work should begin with tests specifically designed to examine these arrivals, generally by using elongated spreads. 3.2 Arrays
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John M 2003 Field Geophysics Third Edition John Wiley and...

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