….. and see what happens.
At last, the equipment from the Azores returns,
and ironically on the same day it arrives out goes another set. This set isn’t going anywhere near as far, nor for so long – its off to a loch in Scotland.
We have been lucky enough to secure some new instruments into the Facility, and we are taking them to a loch in Scotland to give them a test – they will be deployed for a week to test that they fully work – can be deployed successfully onto the seabed and can be successfully recovered, and that they record data that is usable for a section of our users that look at the lowest frequency travelling signals to look at the deepest inner earth – broadband passive seismologists. It is the recording approach that is passive and not the seismologists of course!
We are also sending a set of our existing active-source systems to act as a benchmark comparison.
The new instruments are quite a bit bigger than our existing, and quite a lot heavier – they need to be quite stable on the seabed and sit there for a year or more under normal operations – we are just going to test them for a week.
On arrival at Loch Linhe the equipment was assembled on the quay …
… and put on a dive support boat and taken to the deployment site in the middle of the loch.
After a bit of tootling about deploying all 10 instruments on test …
… an airgun seismic source was deployed to provide some “known” signals.
And 172 shots later, fired along three profiles, its off back to base leaving these instruments sitting quietly on the loch bed listening to the “background”.
Following any deployment, of course, comes the recovery – which is also part of this test.
With the loch water only being 100m deep, rise time from loch bed to loch surface, from the moment of release is short – a few minutes – not the few hours we can sometimes wait when working in the deep ocean.
The surface arrival is ….
…. followed by the catch
and the arrival on deck for data download
in our make shift centre of operations in a cubby hole on the dive boat – have computers, GPS clock, processing system will travel!
The loch bed also turned out to be quite muddy.
Good for instrument settling and sensor coupling; not so good for those having to clean all the equipment.
We wonder what the real cruisers thought we were up to as they passed by – probably not an entertainment on their usual list of choices for the day.
You’ll have to wait for the next episode to see what has been recorded – the data “experts” are working on it!
With thanks to:
Nanometrics Inc.
Exploration Electronics Ltd
Fort William Underwater Trials Centre Ltd
OBS'ing at sea 