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TitreFrequency and magnitude of events
AuteurJackson, L E
SourceEncyclopaedia of natural hazards; par Bobrowsky, P T (éd.); Encyclopedia of Earth Sciences Series 2013, 2013 p. 359-363, 147
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100018
Documentpublication en série
DOI 147
Mediapapier; en ligne; numérique
Sujetsdangers pour la santé; magnitudes des séismes; secousses séismiques; inondations; glissements de terrain; géophysique; géologie de l'ingénieur
ProgrammeNational Guidelines for Natural Hazard Assessment and Mitigation, Géoscience pour la sécurité publique
Résumé(Sommaire disponible en anglais seulement)
The frequencies and magnitudes of potentially hazardous geophysical and hydro-meteorological events have an inverse power relationship: the larger and more energetic the event, the rarer it is in time. The relationship is not open-ended but is limited by physical limits dictated by such factors as plate tectonics and climate. The magnitude-frequency relationship can imply that events of intermediate frequency and magnitude may be the most significant in shaping aspects of the earth's surface. However, rare, extreme events can cause permanent changes to fluvial systems and other aspects of the landscape that would not have occurred under the regime of more frequent and less energetic events. The attributes and frequencies of extreme floods are unlikely to be predicted by analysis of more frequent and lower magnitude stream flow data. For natural hazard processes that are influenced by climatic change, the frequency of an event of a given magnitude can vary depending on the length of time and the specific time interval considered with respect to climatic variation.