Geophysical research from field observations by the Earth Science Division in the 38th Japanese Antarctic Research Expedition (1996-1998)

Abstract

Several geophysical field research observations and geodesic surveys were conducted during the wintering season of the 38th Japanese Antarctic Research Expedition (JARE-38) in 1996-1998. Lithospheric structure and evolution of the Lutzow-Holm Bay region, East Antarctica were obtained from continuous observations by portable broadband seismographs and from gravity surveys on outcrops around the Soya Coast region. Several GPS measurements both on the outcrops along the Soya Coast and on the ice sheet from the coastal area near Syowa Station to the inland of Dome Fuji Station area will give information on crustal uplift due to glacial rebound, on mass reduction and surface movement of the continental ice sheet, and on crustal thickness up to the Dome Fuji Station area. Moreover, some test measurements concerning the seismic refraction/reflection experiments by the SEAL (Structure and Evolution of the East Antarctic Lithosphere) project were carried out in the JARE-38 wintering season. Such instruments as a steam water ejective-type ice/snow-drilling system, an expendable ground system segment (GSS), and long term batteries were repeatedly tested to determine whether they operate properly in Antarctic meteorological conditions. Additionally, seismic array observations using short period seismometers on the ice sheet were conducted in order to investigate the properties of seismic wave propagation on the ice sheet and to detect the lower crustal reflected layers on the Mizuho Plateau, which were already suggested by NMO analyses for the JARE-21 refracted data.