The SEAWATCH Deep Sea Module (SDSM) is designed specifically for the detection of tsunamis. The module
may be fitted to existing SEAWATCH systems or be an integrated part of new systems. The SDSM consisting of
a pressure sensor, a processor, batteries and an acoustic modem, is located on the seafloor. The SDSM
is mounted to a bottom anchor using an acoustic release. This enables easy recovery of the unit when
the batteries are drained after approximately one year of operation. The SDSM is released for retrieval by the
acoustic release.
The SDSM continuously measures the water pressure at the seafloor. Once per hour a measurement is
transmitted to surface buoy enabling verification of the system’s operation. The pressure measurements are
processed by the seafloor processor in real-time and the tidal variations and the variations due to sensor
instability are subtracted from the time series. The resulting data are then analysed for tsunami events. In
the case of a likely tsunami event, the SDSM switches into fast data transmission mode, sending the pressure
time series to the surface buoy, which in turn sends the data to shore using the satellite link.
Onshore, in the Tsunami warning centre, the data reception system would indicate an alarm situation. The
data would at this stage be readily available for the expert team to evaluate, together with seismic data and
other possible sources of information.
So far the SEAWATCH Deep Sea Module has been delivered to Malaysia (3), India (2) and Greece (1). This
turnkey system is delivered as a complete package and is ready to setup and operate on receipt. It can be
configured with hardware and software for operation in shallow or deep water. The integration of the SDSM
with a surface buoy enables the collection of data sets for many meteorological and oceanographic parameters,
providing a truly multi-hazard detection system.
