L’evoluzione tettonica del continente antartico

Abstract

Because of its location, Antarctica represents an observation point of special interest to global seismology. Also, seismology can greatly contribute to the knowledge of Antarctic neotectonics through the study of continental seismicity and lithospheric structure. The sporadic distribution of seismographic stations south of latitude -45 both restricts our knowledge of the Antarctic continent, and leads to a bias in the interpretation of global geophysical properties of the Earth. Installation of seismographic stations should therefore be a priority for an Antarctic program having access to infrastructure in the area and there are particular activities carried on in the framework of the Italian Antarctic program (Programma Nazionale di Ricerche in Antartide, PNRA). In fact, the previously held notion that Antarctica is essentially aseismic has been disproved by using records from established Global Seismic Network stations and recently deployed temporary stations on the Antarctic continent. However, the seismicity observed in Antarctica is very low in comparison with other continental intraplate regions. In the continental intraplate region of Antarctica, earthquakes occur in three settings. Two are likely to have distributions with a tectonic control (although the level may be suppressed by ice-cover); those in the Transantarctic Mountains and scattered events in the interior. Finally, seismicity in the coastal zone and continental margin is likely to be most strongly controlled by the interaction between glacial isostatic adjustment and lithospheric thickness, with a regional tectonic component in some locations.