Speaker
Dr
Luca Naticchioni
(INFN Roma)
Description
In this talk we report the ongoing characterization of the Sos Enattos former mine (Sardinia, Italy), one of the two canditate sites for the Einstein Telescope (ET), the European third-generation interferometric detector of Gravitational Waves. This observatory will be realized in an underground infrastructure: indeed, since either anthropogenic or natural seismic vibrations are dominated by Rayleigh waves, their
amplitude decreases rapidly with depth, improving the detector sensitivity at low frequencies.
The Sos Enattos site lies on a crystalline basement free of horizontal crustal movements, made up with micaschist, quartzite, ortogneiss and granitoids rocks. All these rocks show good geo-mechanical parameters. The absence of groundwater (due to the low porosity of these rocks) is confirmed by the mine drainage, evaluated in about 1 L/s along ~50 km of galleries. In addition, the site is located in a very stable area from the geological point of view, showing low seismicity due to the absence of active tectonics. Finally, the area has a low population density, resulting in a reduced anthropic noise.
A long-term seismic noise measurement was performed between 2012 and 2015 at a depth of about 110m. More recently, in March 2019, a new network of surface and underground seismometers was deployed at the site and is currently monitoring the seismic noise. Most of the energy carried by the seismic waves is due to the microseisms, showing a strong correlation with the waves of the Tyrrhenian sea. Above 1 Hz the seismic noise in the underground levels of the mine approaches the Peterson's low noise model. Horizontal-to-Vertical spectral ratios indicate the lack of significant site amplification effects related to shallow impedance contrasts. Finally, using data recorded during an underground mine blast, we also evaluate the P-waves propagation velocity, the decay distance of the peak ground velocity, and an estimate of the shallow shear-wave velocity profile from the inversion of the Rayleigh-wave dispersion function.
Primary authors
Dr
Alessandro Cardini
(INFN Cagliari)
Dr
Carlo Giunchi
(INGV Pisa)
Dr
Domenico D'Urso
(University of Sassari)
Prof.
Enrico Calloni
(University of Naples Federico II & INFN Napoli)
Dr
Federico Paoletti
(INFN Pisa)
Prof.
Fulvio Ricci
(University of Rome La Sapienza & INFN Roma)
Prof.
Giacomo Oggiano
(University of Sassari)
Dr
Gilberto Saccorotti
(INGV Pisa)
Dr
Luca Naticchioni
(INFN Roma)
Dr
Marco Capello
(INGV Pisa)
Dr
Marco Olivieri
(INGV Bologna)
Dr
Mario Paratore
(INGV Pisa)
Prof.
Massimo Carpinelli
(University of Sassari)
Mr
Maurizio Perciballi
(INFN Roma)
Dr
Michele D'Ambrosio
(INGV Pisa)
Dr
Paola Puppo
(INFN Roma)
Prof.
Piero Rapagnani
(University of Rome La Sapienza & INFN Roma)
Prof.
Rosario De Rosa
(University of Naples Federico II & INFN Napoli)
Dr
Sonja Gaviano
(INGV Pisa)
Dr
Stefano Cuccuru
(University of Sassari)
Dr
Valeria Sipala
(University of Sassari)
Dr
Valerio Boschi
(INFN Pi)
