The recent pumice eruptions of Mt. Pelée volcano, Martinique. Part I: Depositional sequences, description of pumiceous deposits

Abstract

Abstract Mount Pelee is one of the most active volcanoes of the Lesser Antilles arc, with more than twenty eruptions over the last 5000 years. Both nuee ardente-type eruptions, which are well known, and pumice eruptions, although little known, are very common in the stratigraphic record. The four younger pumice eruptions, P4 (2440 y.B.P.), P3 (2010 y.B.P.), P2 (1670 y.B.P.) and P1 (650 y.B.P.) can be used to reconstruct the eruption sequences. The various pumiceous deposits can be described as fine lithic ash layer, Plinian fall deposits, pumice and ash flow deposits with associated ash cloud fall deposits, and pumice surge deposits. Three kinds of depositional sequences have been defined. The distinctions between them are based on the occurrence of an initial Plinian phase and the generation of intraflow pyroclastic surges. The pumice eruptions of Mt. Pelee are small in intensity and magnitude, as expressed by the dispersal of their products and by the total mass of erupted material which is estimated to be less than 1 km3 in each case. The pumice fall deposits have dispersal characteristics of small Plinian eruptions, close to the sub-Plinian type. Nevertheless, the probability of an occurrence of a new pumice eruption at Mt. Pelee is high, and the widespread distribution of pumice deposits around the volcano suggests that such an eruption is a major volcanic risk during the present stage of activity.