MOIST
Multidisciplinary Oceanic Information SysTem

SMO 1 - Seismometer - RAW dataset

Metadata

Instrument: Guralp CMG-1T 3 component broadband seismometer (360 s-50 Hz)
Investigator: Stephen Monna (INGV)
Project: SMO
Observatory: NEMO-SN1

Abstract: This digital database comprises seismological data recorded during the SMO project by a 3 component broadband seismometer. The sensor was installed on the the NEMO-SN1 (Neutrino Mediterranean Observatory - Submarine Network 1) seafloor observatory, offshore of the Eastern coast of Sicily (Southern Italy) at a depth of 2036 m. The seismometer is installed in a dedicated vessel integrated in a separate structure connected to the observatory via a special mechanical release. To guarantee a good coupling with the sea bottom, the structure is disconnected just after the observatory touch-down and kept linked to the frame by a slack rope (Favali et al., 2006). The sensor is connected to a 24 bit digitizer on the observatory. The GPS signal is transmitted underwater to the digitizer, so that the data packages are time-stamped locally.

Purpose: This project is a continuation of GNDT 1 and GNDT 2 where the main objective was to establish a multiparameter seafloor observatory off-shore eastern Sicily. One of the main aspects of SMO remains long-term geophysical monitoring and broad-band seismic measurements from this site is of great interest given its proximity to the Etna volcano (~ 50 km) and to offshore seismogenic structures where some of the most destructive earthquakes in Italy took place (some of them generated tsunamis). For this reason a tsunami detection systems is implemented on-board the observatory and the seismometer is an important component.

Quality of data: The Z (vertical) and N components have recorded data of good quality for the duration of the deployment. The E component recorded only electronic noise from the beginning of the experiment till the 24th of August (~9 UTC) due to the fact that the mass was not released. After we were able to release the mass the E component recorded good quality signal for the rest of the mission. Due to tests, during June 2012, there are periods with electronic disturbances and presence of gaps in the data. A periodic disturbance is visible on all components due to the acoustic signal emitted when the ADCP is sampling (2 profiles/hour).