The Antarctic Seismographic Argentinean Italian Network - ASAIN Improving the instrumental coverage in Antarctica

Abstract

Scientific investigations of the Scotia Sea region are crucial to understand the history of the Antarctic continent tectonic evolution and the influence of the aperture of the Drake passage in establishing the Circumpolar Antarctic Current, as stressed by many authors (e.g. Lodolo, 2008). The Scotia Sea occupies a roughly rectangular area of about 900.000 km . This area is limited on three sides by the Scotia Arc, formed by islands and oceanic ridges, which is a remnant of the mountain chain that joined the South American Andes to the Antarctic Peninsula. The western border is represented by the about 1000 km wide Drake passage, that separates today the Tierra del Fuego in South America from the Antarctic continent. A review of the tectonics and evolution of the Scotia Sea can be found in Barker, 2001. The start of the geophysical studies in this area dates back to several decades ago, but only after 1990 instrumental passive seismology started to be widely applied to investigate the crustal properties and the properties of the seismic sources responsible for the strong seismicity level observed along the Scotia plate boundaries. ASAIN started operation in 1992 when a temporary seismograph was installed at the Argentinean Base Esperanza. It grew quickly during the nineties and today five stations are operated in Antarctica and two in Tierra del Fuego. All the Antarctic stations transmit real-time data to the OGS and to the Instituto Antartico Argentino. Esperanza (ESPZ), Jubany (JUBA), San Martin (SMAI) and Orcadas(ORCD) stations also participate in the Virtual European Seismographic Broadband Network (VEBSN) transmitting real time data to the Orfeus Data Centre. On January 16 , 2009 BELA station was added to the network. It is operated at the southernmost Argentinean Base Belgrano II (77° 52' S, 34° 37' W ) located on a rocky outcrop (Nunatak Bertrab) on the Filchner barrier. Its inclusion in the VEBSN is also planned. ASAIN data real-time acquisition is performed using SCREAM software, but also Earthworm and Antelope software are being tested at the OGS Seismological Research Centre.