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2.3 OUTLINE PLAN OF THE EXPERIMENT
The central concept of the experiment at sea is shown in the plan in
Fig. 2.2 and cross-section in Fig. 2.3. The specific details of the
listening equipment packages, such as the, instrument responses, package
sizes etc, are described in the next chapter. The logistics of the
experiment at sea required two ships: RMAS Salmaster and RMAS Goosander.
Many of the underlying reasons and background information for adopting
specific details in this plan are explained later in this report.
It was decided to opt for six PUll-up Shallow Vater Seismometers
(PUSSes) to be deployed on the sea bottom in a line between the coast and
the shot point. The chosen shot point was located around 57°7N, 0045V.
The recording great circle line extends from the coastal seismometer
station at Tentsmuir in Fife (TMA in Fig. 2.2) , to the shot point. Each
PUSS was to be deployed from the Salmaster in about 50-70 m of water.
Once deployed each PUSS is self contained
have to be retrieved after detonating the
3-component geophone and one hydrophone.
90 minutes of 4-channel data; this 90
but is not disposable and would
charge. Each PUSS contains one
Each PUSS can record a total of
minutes can be divided into
pre-selected time windows of arbitrary length and 10 minutes was the
selected option. Coordination of PUSS recording time windows and
potential firing times of the explosion is obviously vital.
One BGS sea bottom package was to be deployed by the Salmaster on the
sea-bed in about 50-70 m of water on the shore-shot line (TMA to explosion
in Fig 2.2). This package is not self contained. It would need to be
cable- linked to the moored and stationery Salmaster, either directly or
via mooring buoys. This cable would carry signals received at the BGS sea
bottom package to recorders on board the Salmaster. The BGS sea bottom
package contains one 3-component piezo-electric seismometer and one
hydrophone. In addition, it was necessary for the recorder on the
Salmaster to record an accurate time standard such as MSF transmitted from
Rugby.
A vertical hydrophone string (VHS) would also be deployed on the
shore-shot line near to the BGS sea bottom package (Fig.2.3) and would be
deployed by the Salmaster. The VHS would extend to the sea bottom and
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