60th anniversary of gravimetry

Celebration of the 60th (1954-2014) anniversary of gravimetry in Strasbourg

One day during the G2 workshop will be devoted to the celebration of the 60th anniversary of the gravimetric observations (1954-2014) in Strasbourg. The first observations as continuous series of a few months were done in 1954 by Professor Robert Lecolazet  with a North American spring gravimeter. The instrumental improvements (feedback system) and progress in the tidal analysis rapidly led to the precise determination of tidal waves. A three year (1964-1967) series of the North American gravimeter led to the detection of the Earth's core resonance effect which alters the amplitudes and phases of the diurnal waves K₁ and PSI₁.

This discovery was later confirmed by gravity records between 1973 and 1985 obtained  with another spring meter (LaCoste Romberg ET005) at station J9 which is an underground bunker near Strasbourg built in 1875.  This tradition of measuring time-varying gravity was further extended by the installation in 1987 of the first superconducting gravimeter GWR T005 which was operating till 1996; a second compact type (GWR C026) superconducting gravimeter was installed  in continuity and is still operating today. This last gravimeter is part of the French Observatory System and belongs to the GGP (Global Geodynamics Project) international network of  superconducting gravimeters. The data from this gravimeter allowed numerous studies on Earth's structure and dynamics.

This celebration day will start with invited conferences on time-variable gravity. A visit to the Strasbourg Gravimetric Observatory will be organized in the afternoon followed by a dinner.