MOIST
Multidisciplinary Oceanic Information SysTem

NEAREST 1 - Seismometer - RAW dataset

Metadata

Instrument: Guralp CMG-40T 3 component broadband seismometer (30 s-50 Hz)
Investigator: Stephen Monna (INGV)
Project: NEAREST
Observatory: GEOSTAR

Abstract: This digital database comprises seismological data recorded during the EC NEAREST project by a 3 component broadband seismometer. The sensor was installed on the GEOSTAR deep-sea multidisciplinary observatory, in the Gulf of Cadiz (Portugal). In the same vessel together with the seismometer there was an accelerometer. Both sensors were connected to a 24 bit digitizer, and their time reference came from an external rubidium clock connected to the digitizer.

Purpose: The seismometer was part of a prototype of tsunami early warning system together with a pressure meter on board GEOSTAR. Also, the sensor was used together with the other 25 OBS deployed in the NEAREAST experiment, to better define the local seismic sources and tectonic structures.

Quality of data: The data series is complete for all working sensors (see problems below), 95 % of expected bytes has been recorded. Strong long period disturbance on seismometer and accelerometer channels due to continuous re-centring of levelling platform (144 s recurrence period) due to Guralp electronics.

Publications

• Geissler, W. H., et al. (2010), Focal mechanisms for sub-crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment, Geophys. Res. Lett., 37, L18309, doi:10.1029/2010GL044289.