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Seismicity and seismic gap in the Lesser Antilles arc and earthquake hazard in Guadeloupe |
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| Authors: | J Dorel |
| Institution: | Laboratoire d'Etude Géophysique des Structures Profondes associéau CNRS, Institut de Physique du Globe de Paris, UniversitéP. &M. Curie 4, place Jussieu, Tour 14, 75230 Paris Cedex 05, France |
| Abstract: | Summary. A seismic study of the Lesser Antilles arc has been carried out, first for the period 1950–1978, for which we can use local seismic networks to draw maps of instrumental seismicity, then for the period 1530–1950, for which we have catalogues of felt earthquakes. The striking feature of the spatial distribution of foci is the cluster of epicentres in the northern half of the arc; all large earthquakes ( M > 7.5) are located north of 14° latitude. Seismicity cross-sections through the arc show a variable dipping subduction zone along the arc; the deep seismic zone is steeper in the centre of the arc than on the extremity. The time-space diagram for historical seismicity, and the evidence of a seismic gap at the east of Guadeloupe lead us to consider the northern half arc as a likely site for a large earthquake in the near future. The seismic slip rate calculated from all major earthquakes since 1530 is of much greater value than that obtained from recent plate tectonic models, suggesting that the recurrence rate of earthquakes is more than many hundreds of years with a possible aseismic creep. |
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