ALBERT

Description: The Bransfield Strait is a seismically active extensional rift located between the Antarctic Peninsula and the South Shetland Islands that is forming in continental crust but may be near the transition to seafloor spreading. As part of the BRAVOSEIS project, an international effort focused on the seismological research of submarine volcanoes and rift dynamics in the Bransfield Strait, we deployed a nested, amphibious seismic network in the area. The regional network comprises 15 broadband land seismometers in the South Shetland Islands and the Antarctic Peninsula; 9 broadband OBSs deployed across the Central Bransfield Basin; and 6 hydrophone moorings spanning the rift. It covers an area of 200x100 km2, with an average inter-station distance of ~30 km. Additionally, 15 short-period OBSs were deployed in a tight cluster around Orca volcano, a submarine volcanic edifice south of King George Island. This local network has an aperture of 20 km, with an average inter-station distance of ~4 km. Eight land stations were deployed in February 2018, with the remainder deployed in January 2019. All instruments will be recovered in early 2020. The recorded seismicity will be analyzed using state-of-the-art techniques. The results may shed light on the crustal structure and tectonic regime in the South Shetlands region; elucidate among different theories on the origin of the Bransfield rift; image the location and extent of magma accumulation zones related to submarine volcanic structures; and assess the internal processes that occur in the submarine volcanoes of the Bransfield area.