Volcanism in the Azores Archipelago exhibits a strong tectonic control and is frequently taking place at the rift zones that intersect the central volcanoes. In particular, there is abundant evidence of repeated volcanic activity close to the coastlines and the eruption of Capelinhos from 1957 to 1958 was the most recent emergent, submarine basaltic event of that kind.

 

It is regarded as a classical surtseyan event where the contact of rising basaltic melt with sea water led to violent explosions (hydromagmatic activity). In later stages, the growth of a subaerial cinder cone progressively prevented a direct melt-water contact and marked the transition to magmatic activity where expanding magmatic gas is the main driving force for the explosions.

 

In this project, the subaerial deposits of Capelinhos will be investigated in detail for their volatile content and transportation conditions of the pyroclastic density currents (PDC). Analysis will comprise the study of:

1) Distribution and Stratigraphy of eruptive products.

2) Geochemical and petrographical features to describe co-existing mineral phases, reveal the existence of melt inclusions, and investigate the preservation state of glass from quenched samples.

3) Volatile content from melt inclusions in crystals and glass to understand pre- and syn-eruptive degassing and possibly constrain the effect of magmatic gas during the hydromagmatic activity.

4) Granulometry and componentry of the deposits of PDC to constrain eruptive and transportation processes.

 

The results will contribute to a better understanding of emergent, submarine basaltic eruptions in general and Capelinhos in particular. This may be used to elaborate emergency plans and produce volcanic hazard maps that are essential for adequate risk assessment.