Antoine Delepoulle (CLS, France); Faugère Yannice (CNES, France); Mauricio Fuentes (Universidad de Chile, Programa Riesgo Sismico, Chile); Hélène Hébert (CEA, France); Gabriela Herrera Malig (Universidad de Chile, Programa Riesgo Sismico, Chile); Jean Roger (Earth Structure and Processes Department, GNS Science, Lower Hutt, Aotearoa New Zealand, New-Zealand); Patricio Toledo (Universidad de Chile, Programa Riesgo Sismico, Chile); Francisco Uribe (Universidad de Chile, Programa Riesgo Sismico, Chile)

Two years after the first image of a tsunami in the Southwest Pacific Ocean (Faugère et al., 2024), SWOT has caught new tsunami wave features in the South Atlantic Ocean on 2 May 2025, combining the unprecedented resolution and accuracy of the KaRIn instrument (Ka-band Radar Interferometer) and tsunami predictions. The satellite sea-surface height observation and the tsunami simulation show clear and similar wave-like structures and planar wavefronts. The tsunami was initiated about 5 hours earlier within the Drake passage ~100 km off Cape Horn, the southernmost tip of Chilean Patagonia, by a rare Mw 7.4 earthquake. To prevent a potentially severe impact on the coastal populations mainly associated to limited knowledge of tsunamis in the region, Hydrographic Service of Chilean Navy issued an evacuation alert in South of Chile and Antarctica. This alert was cancelled a couple of hours later.

In the Drake Passage, a remote region of the globe, seismic and tsunami in-situ measurements remain severely sparse with a bad azimuthal coverage, despite the existing active tectonic features bordering the Scotia Plate, including the Shackleton fracture zone to the west. In this presentation, we show how, by analyzing the SWOT dataset, the complex source processes that triggered the tsunami can be better constrained, notably comparing the 2D tsunami wave field photographed by SWOT with multiple tsunami numerical models. SWOT could help better understand the tectonic peculiarities of a poorly known tectonic zone and indirectly improve the warning systems.