HR: 1340h
AN: MR43A-0865    [Abstracts]
TI: Observation of the Fluid Core Resonance With two Laser Extensometers at Gran Sasso, Italy
AU: * Crescentini, L
EM: luca.crescentini@unicam.it
AF: Dipartimento di Scienze della Terra, Universit\`a di Camerino, Via Gentile III da Varano, Camerino (MC), 62032 Italy
AU: * Crescentini, L
EM: luca.crescentini@unicam.it
AF: Laboratori Nazionali del Gran Sasso - INFN, SS 17 bis, km18+910, Assergi (AQ), 67010 Italy
AU: Amoruso, A
EM: antonella.amoruso@aquila.infn.it
AF: Dipartimento di Fisica, Universit\`a dell'Aquila, Via Vetoio 10, Coppito (AQ), 67010 Italy
AU: Amoruso, A
EM: antonella.amoruso@aquila.infn.it
AF: INFN - Gruppo Collegato L'Aquila, Via Vetoio 10, Coppito (AQ), 67010 Italy
AU: Ruggiero, L
EM: ruggiero@sa.infn.it
AF: Dipartimento di Fisica, Universit\`a di Salerno, Via S. Allende, Baronissi (SA), 84081 Italy
AB: Since several years two laser extensometers are operating at a depth of 1400 m in the Gran Sasso underground observatory (Central Italy). The two orthogonal baselines, striking N66E and N24W, are 90-m long. Nominal sensitivity is about $3 \times 10^{-12}$ and recording rate is 5 Hz. Until 1999 only one Michelson interferometer measured difference in extension between the two baselines in an equal-arm configuration, after this year two independent unequal-arm interferometers are working, monitoring extension along two orthogonal directions. Tidal analysis of strain data has been performed using different codes in order to evidence the fluid core resonance effect in the diurnal tidal band and study the resonance function. The unusual depth of the station largely reduces contamination caused by atmospheric effects in the diurnal band of recorded tides, as indicated by the not so large amplitude of the S1 wave. Predicted ocean loading effects are small, mainly for one of the two monitored directions. In this condition uncomplete removal of oceanic tidal loadings and atmospheric effects can be expected to to affect results to a minor extent. Our results will be compared with predictions and previous works.
DE: 7207 Core and mantle
DE: 1249 Tides--Earth
SC: Mineral and Rock Physics [MR]
MN: 2004 AGU Fall Meeting