A network of seismometers (consisting of a combination of seismic sensors and data acquisition units) independently records regional seismicity. Stations communicate either with the central computer via digital radios, satellite data link or cellular modem. Alternatively, seismic data can be recorded to a portable USB drive using StandAlone mode. Seismic processors and netADCs are linked to GPS modules to provide accurate time synchronisation between regional stations.
Use of common cellular modems minimises infrastructure set-up costs. Seismic information is downloaded from all stations every day at midnight. Seismograms of common events are post-associated for off-line processing and interpretation.
The stations communicate with a central server via a digital satellite data link, local internet connection or WiFi link to the internet or central server.
The low power consumption of the seismometer (less than 0,6W/channel) and digital radio allows for the use of an inexpensive solar-panel-and-battery unit, making the seismic station completely independent.
Typically, 1 Hz tri-axial geophones are used for this application. A vault is constructed to house the sensor and seismic station. Each netADC data acquisition unit can monitor up to eight seismic signals, but usually only three channels are used in this instance.
SEISMIC DATA PROCESSING AND INTERPRETATION
The seismograms of every seismic event that triggers multiple stations are post-associated on the seismic controller. Seismograms are then exported to SEISAN format for processing by a tectonic seismology package. Additionally, SeedLink (MiniSEED) data sources, such as those provided by SeisComP, can be added, which allows for the simultaneous use of local and remote data. Various configurations are possible to seamlessly integrate the IMS system with existing regional and global monitoring operations by adding any combination of the IMS automatic processing and web-based data-monitoring interfaces.