Mariana Andrade: Best PhD Thesis in Earth Sciences 2023

IDL PhD student Mariana Andrade won the best PhD thesis in Earth Science 2023.

This PhD project used lake and subaerial tephrostratigraphy, geochronology, geomorphology and glass shard geochemistry to reconstruct the recent eruptive history of Flores Island (Azores) and investigate the role of groundwater (as a function of rainfall variability) in triggering phreatomagmatic interactions and hence modulate volcanic hazard. Observations show that Flores experienced at least six eruptions during the Holocene, taking place at 6280, 4490, 3430, 3330, 3250, and 3180 cal yr BP, and assuming a variety of eruptive styles. Critically, eruption reconstructions show that groundwater played an important role in the eruptions at Flores, by transforming low-explosivity basaltic eruptions into highly explosive phreatomagmatic events. Water/magma interactions at Flores are apparently controlled by variations in eruption rates, associated with erosion and widening of volcanic conduits, with long-term rainfall variability having a limited correlation with phreatomagmatism. This study reinforces the notion that, on island volcanoes saturated with near-surface aquifers and subjected to small-volume monogenetic volcanism, eruption rates have a determining role in triggering phreatomagmatism and consequently amplifying volcanic hazard.