Il nuovo OBS/H dell’INGV

Abstract

In 2005, thanks to the 3-year agreement between Dipartimento Nazionale della Protezione Civile (DPC) and Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Centro Nazionale Terremoti (CNT), the project of the first Italian “Ocean Bottom Seismometer with Hydrophone” (OBS/H) for long-term deployment was developed at the OBS Lab of the Gibilmanna Observatory (Sicily). The drawing of the instrument started in January 2005 and, after 18 months, the prototype was ready for test in laboratory, in shallow and deep water. Afterwards, the first OBS/H was tested during an oceanographic campaign on the Marsili submarine volcano, from the 10th to the 21st of July 2006.More than 1000 events of several kinds were recorded: 817 VTB (Volcano Tectonic events, B-type), 159 HF (High Frequency events), 53 SDE (Short Duration Event), 8 regional events localized by INGV land network, 10 not localized events, 1 teleseismic event an 2 rockfall events. The INGV OBS/H are equipped with: - Nanometrics Trillium 120p seismometers (theoretical flat response between 120s and 175 Hz) installed in a 17 inches glass sphere on a Nautilus gimbal for the leveling or Guralp CMG40T-OBS (flat response between 60s and 100 Hz); - Cox-Webb Differential Pressure Gauge (bandwidth 500s-2Hz) or OAS E-2PD hydrophone (0-5kHz); - 21 bits, 4 channels SEND Geolon-MLS digitizer with sampling frequency up to 200 Hz.