GEODIS (GEOphysical DIving Saucer): A portable ocean bottom broadband seismic station L. Beguery * , JP. Montagner ♦ , JF. Karczewski * , S. Cacho * , JC. Koenig * , J. Savary * , E. Stutzmann ♦ , P. Lognonne * , G. Roult ♦ Institut de Physique du Globe de Paris Departements Sismologie: * OFM / ♦GEOSCOPE Département des Etudes Spatiales: * 4, avenue de Neptune 94107 Saint Maur des fossés Cedex France beguery@ipgp.jussieu.fr 1/ Scientific goals The last ten years have seen the simultaneous developmentf a global seismic network coordinated through the FDSN (Romanowicz and Dziewonski, 1986) and of portable broadband seismic arrays. The same approach can be followed for improving our scientific understanding of the Earth processes below oceanic areas. These two components of ocean bottom geophysical networks, might be coordinated by ION (International Ocean Network; Suyehiro et al., 1995). They are complementary they enable to investigate the Earth structure and active processes at different spatial and temporal scales. Permanent Ocean Bottom Observatories and temporary portable seismic stations are sharing common technological problems. However, issues of power-supply and of real-time transmission are more crucial for an observatory than for a temporary station. Following the recommendation of ION (Montagner and Lancelot, 1995) concerning the operation on the bottom of the sea of Geophysical instruments and particularly VBB Seismometers, the Geoscope/OFM/VBB group of the IPGP has developed a prototype of an autonomous VBB seismological station named GEODIS. This station might be one basic and central element of a permanent observatory. It relies on the use of adapted VBB sensors issued from space experiments and technology and on improved electronics compared with previous ocean bottom experiments (Montagner et al., 1994a,b; Stakes et al., 1998; Romanowicz et al., 1998; Stutzmann et al., 2001)