ETUDE GEOPROSPECTIVE D'UN SITE DE STOCKAGE. VOLUME 5 - LES MOUVEMENTS VERTICAUX - CAUSES ET QUANTIFICATION
Units used for the measurements of vertical crustal movements are usually numerous. A single expression is proposed : the Bubnoff unit (1 mm per 1000 years). Vertical movements are due to numerous causes. Volcanism leads to alternative uplift and breakdown. Isostatic compensation of deglaciated areas or connected to deep crustal movements may apply to large areas. Geoidal shape variations give displacements, whose origin is often difficult to explain. Earth tides caused by moon-sun cyclic motion are of low amplitude. Preseismic dilatancy gives sometimes noticeable uplift. Earthquakes correspond to deep changes of equilibrium in stresses and may lead to metric superficial deformations. Orogeny and subsidence are long-lived phenomena (several millions of years) applying to wide surface (thousands or millions of square kilometers). Measurements of vertical movements are instrumental, thus giving instantaneous values regarding to geological times, or refer to long duration phenomena whose speed is a mean one. A speed given without information on the time span considered and the method used is useless. It is also necessary to mention the geodynamic context : plates boundary, orogenic belt, basin, graben... A collection of data is given classified according to the type of geotectonic province. Speeds of vertical movements range from 1 to 106 mm/1000 years; there exist phenomena able to uplift or low an area of 1 km/1000 years in some paroxysmic cases.
Bibliographic Reference: EUR 9866 FR (1985) MF, VOLUME 5, 49 P., BFR 150, BLOW-UP COPY BFR 245, EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989126032001 / Last updated on: 1989-01-01
Available languages: fr