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palaeoseismology
palaeoseismology Palaeoseismology is the study of prehistoric earthquakes using geological and geomorphological evidence. ‘Prehistoric’, in this context, is commonly taken to mean the past 500 000 years in contrast to the usual elastic use of this term. Palaeoseismology is of importance in assessing earthquake hazard, especially in regions where the time interval between damaging earthquakes is measured in thousands of years, and thus exceeds the length of our instrumental and historical records.
The two principal methods of palaeoseismological investigation are the analysis of (1) fault scarps and (2) sedimentary strata that have been offset or internally deformed by movements on an earthquake fault. The principle of analysing fault scarps to determine the magnitudes of, and intervals between, past earthquakes rests on the premise that the shape of fault scarp is controlled by denudational processes from the moment that it formed during an earthquake (see fault scarp). Where, in a natural outcrop or specially excavated trench, increasingly large offsets can be measured downwards across an earthquake fault it is possible to calculate the time between increments of movement, provided that the strata can be precisely dated. If sedimentary horizons that have been internally deformed by earthquake shaking can be distinguished from those related to other processes, and if they too can be dated, it is again possible to work out when the earthquakes occurred. Paul L. Hancock |
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PAUL HANCOCK and BRIAN J. SKINNER. "palaeoseismology." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "palaeoseismology." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O112-palaeoseismology.html PAUL HANCOCK and BRIAN J. SKINNER. "palaeoseismology." The Oxford Companion to the Earth. 2000. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-palaeoseismology.html |
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palaeoseismology
palaeoseismology The study of ancient earthquakes, primarily by mapping zones of previous earthquake destruction by observation or from historical records.
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "palaeoseismology." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "palaeoseismology." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O13-palaeoseismology.html AILSA ALLABY and MICHAEL ALLABY. "palaeoseismology." A Dictionary of Earth Sciences. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-palaeoseismology.html |
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