Post-caldera volcanism of Deception Island (Antarctica): new insights from Tephra studies and Port Foster Bay volcanic deposits

Abstract

[eng] Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica and has experienced over 20 explosive eruptive events in recent centuries. Recent eruptions in 1967, 1969, and 1970, as well as volcanic unrest episodes in 1992, 1999, and 2014–2015, highlight the ongoing and potential future volcanic activity on the island. Despite this volcanic activity, the region has witnessed a substantial increase in scientific bases, tourist activities, and air and vessel traffic in the last decades. This surge in interest has raised concerns as the escalating infrastructure and population in the area are increasingly exposed to the risk of future eruptions. This enhanced exposure necessitates an urgent, and accurate, long-term assessment of the volcanic hazard posed by Deception Island. Previous attempts at such assessments have been limited by the incompleteness of the island’s eruptive record. The complexities of Deception Island's magmatic and volcanic evolution demand continued significant research efforts to enhance our understanding and contribute to more effective hazard assessments. This Doctoral Thesis combines diverse research lines, revealing crucial insights into the island's past, present, and potential future volcanic evolution as well as the associated impact of future eruptive events. The investigation encompasses two primary research lines: (1) the study of Port Foster's most relevant eruptive episode, focusing on the formation of the Stanley Patch volcanic edifice, and (2) the identification, compositional, and textural characterization of tephra layers sourced from Deception Island. These research lines are integral to enhance our understanding of the island's geological evolution since the caldera collapse. The combination of research lines pertaining to Port Foster and tephra studies provides significant advancements in our understanding of the post-caldera volcanic activity of Deception Island. The insights gained not only contribute to our comprehension of the island's geological evolution but also serve as a basis for accurate hazard assessments, comprehension of Deception Island’s post-caldera volcanic activity, its past and future evolution, and the potential impact of future eruptive events.