Obiettivo The ultimate goal of this project is to elucidate the physics of the processes by which magma, rising towards the surface of the Earth, vesiculates and fragments to produce explosive volcanic eruptions. We are employing a multi-disciplinary approach involving theory, laboratory experiments and fieldwork. We wish to enlarge the scope of the field work by studying an ancient volcanic terrain in the east Rhodopian mountains of Bulgaria, in collaboration with Dr. Y. Yanev of the Geological Institute of the Bulgarian Academy of Sciences. The explosive volcanism in the east Rhodopian mountains took place between 37 and 30 million years B.P. This terrain is now deeply dissected by erosion, and the superficial parts of the conduit systems are now exposed at the surface. These exposures will allow us to observe both the products ejected in the explosive eruptions, and the near surface geometry of the conduit system that produced them. A number of these eruptions underwent a transition of regime from an explosive phase to an effusive phase, as shown by exposures of lavas intruding into the pyroclastic products of the same vent. Such cases provide evidence that the level at which magma fragments can change during an eruption - an important constraint on physical models of fragmentation. Eruption transitions may be related to the evolution of the conduit geometry by erosion during the explosive phase. We hope that these bulgarian field examples will provide us with the possibility to reconstruct in specific cases how the eruption regime may have evolved, with, in addition, the possibility to constrain the superficial geometry of the conduit system. This field work will add a new dimension to our project, as the field work already begun is concentrated on studying the fragments ejected in relatively recent eruptions of potentially dangerous european volcanoes. These fresh fragments provide us with evidence of the geometry and proportions of gas and liquid phases as fragmentation took place, but we have little or no information on the geometry of the conduit system feeding these eruptions. Programma(i) IC-PECO/COPERNICUS - Scientific and technological cooperation between the European Community and European non-member countries, 1992- Argomento(i) 01 - CEEC participation in ENVIRONMENT programme Invito a presentare proposte Data not available Meccanismo di finanziamento CSC - Cost-sharing contracts Coordinatore Institut de Physique du Globe de Paris Contributo UE Nessun dato Indirizzo 4 place Jussieu 75252 Paris Francia Mostra sulla mappa Costo totale Nessun dato Partecipanti (1) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto GEOLOGICAL INSTITUTE 'STRASHIMIR DIMITROV' - BULGARIAN ACADEMY OF SCIENCES Bulgaria Contributo UE Nessun dato Indirizzo 24,Academician Georgi Bonchev str. 24 1113 SOFIA Mostra sulla mappa Costo totale Nessun dato
