Integrated Ocean Drilling Program, United States

Integrated Ocean Drilling Program Expedition 340, the "Lesser Antilles volcanism and landslides" project, is designed to give us a better understanding of the constructive and destructive processes related to volcanism along island arcs. Processes occurring along these arcs are among the most fundamental occurring on Earth, as roughly 50% of volcanism along the circum-Pacific ring of fire is associated with island arcs. Nonetheless, several aspects of this type of volcanism, such as the processes controlling the changes and diversity in magmatism and eruptive activity on individual islands as well as along an arc or the emplacement processes of large debris avalanches, need to be better constrained. Identification of the controlling mechanisms of these processes is essential because of their potential association with large geohazards (explosive eruptions and tsunamis). Our knowledge of island arc volcanism is mainly derived from on-land studies. It has been shown that the on-land geological record is far from complete and that only a combined record of marine and on-land deposits can give us a complete picture of volcanic activity. The Lesser Antilles arc is especially suited for a project like this, as it is very well studied, and thus the necessary information exists for making such a drilling project a success. In addition, magmatism and eruptive activity along the arc are quite diverse in space and time, the frequency of flank collapse resulting in deposition of debris avalanches is high, and the style of flank collapse varies along the arc. Thus, we will be able to sample deposits related to a large diversity of processes in a short time span. In general, core and logging data retrieved during this expedition will be used to investigate the magmatic evolution and the eruptive activity in space and time along the Lesser Antilles arc and to identify the mechanisms controlling triggering, transport, and deposition of volcanic debris avalanches, including an assessment of volcanic hazards potentially coupled with eruptive processes and debris avalanche emplacement.