Abstract In the last two centuries, demographic expansion and extensive urbanization of volcanic areas have increased the exposure of our society to volcanic hazards. Antarctica is no exception. During the last decades, the permanent settlement and seasonal presence of scientists, technicians, tourists and logistical personnel close to active volcanoes in the south polar region have increased notably. This has led to an escalation in the number of people and the amount of infrastructure exposed to potential eruptions. This requires advancement of our knowledge of the volcanic and magmatic history of Antarctic active volcanoes, significant improvement of the monitoring networks, and development of long-term hazard assessments and vulnerability analyses to carry out the required mitigation actions, and to elaborate on the most appropriate response plans to reduce loss of life and infrastructure during a future volcanic crisis. This chapter provides a brief summary of the active volcanic systems in Antarctica, highlighting their main volcanological features, which monitoring systems are deployed (if any), and recent (i.e. Holocene and/or historical) eruptive activity or unrest episodes. To conclude, some notes about the volcanic hazard assessments carried out so far on south polar volcanoes are also included, along with recommendations for specific actions and ongoing research on active Antarctic volcanism.

Abstract The break-up of Gondwana during the Early–Middle Jurassic was associated with flood basalt volcanism in southern Africa and Antarctica (Karoo–Ferrar provinces), and formed one of the most extensive episodes of continental magmatism of the Phanerozoic. Contemporaneous felsic magmatism along the proto-Pacific margin of Gondwana has been referred to as a silicic large igneous province, and is exposed extensively in Patagonian South America, the Antarctic Peninsula and elsewhere in West Antarctica. Jurassic-age silicic volcanism in Patagonia is defined as the Chon Aike province and forms one of the most voluminous silicic provinces globally. The Chon Aike province is predominantly pyroclastic in origin, and is characterized by crystal tuffs and ignimbrite units of rhyolite composition. Silicic volcanic rocks of the once contiguous Antarctic Peninsula form a southward extension of the Chon Aike province and are also dominated by silicic ignimbrite units, with a total thickness exceeding 1 km. The ignimbrites include high-grade rheomorphic ignimbrites, as well as unwelded, lithic-rich ignimbrites. Rhyolite lava flows, air-fall horizons, debris-flow deposits and epiclastic deposits are volumetrically minor, occurring as interbedded units within the ignimbrite succession.

Abstract Young volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

Abstract The Gebra–Magia Complex is an important example of a submarine mass-movement composite located on the lower continental slope of the Antarctic Peninsula (Central Bransfield Basin). Continuous instability dynamics over time is inferred to have affected the palaeo-trough-mouth fans present in the study area. The depositional architecture and the outstanding relief of the Gebra Valley, which is the most striking morphological feature in the area, determine the asymmetrical morphology of the complex. This complex is characterized, from east to west, by an open-slope margin flanking the sidewall of the Gebra Valley, the Gebra Valley itself and a SW margin that is connected to the Magia area by a large scar approximately 7.8 km to the SW. The Gebra Valley is a Quaternary debris valley resulting from repeated large-scale mass-transport and cut-and-fill processes. In contrast, the Magia area is dominated by unchannelized sedimentary instability processes, resulting in a different sedimentary architecture and morphology. The near-surface sediments in the Gebra–Magia Complex document the continuous occurrence of recent mass movements, as also evidenced by flows transported downslope as unchannelized or channelized flows. Climate and tectonic activity are considered the primary factors controlling the development of the complex.