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Hi Dick,
Thanks for your reference to the British Geological Survey! I found the 1997 earthquake in the area some 2 miles south-west from the Urquhart Castle (latitude 57.29), but there was nothing in the ‘Historical earthquake layer’ section. It is most unfortunate that they don’t have historic records for the whole 20 century.
Alex |
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| Subject: | | Re: The Loch Ness... Moose? |
| From: | |
Dick Raynor
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posted
Wed, Jan 9 2008, 3:09am
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Hi Alex,
I had also thought of the grebe explanation as being most likely, but I didn't want to shoot all of your foxes in a single post!
The BGS records marked on the map of Loch Ness are "instrument recorded events" and quite small in magnitude so may not have even been detectable before the automatic recording instruments network was established in the 1970's. I'm not even sure where they are located, but I did come across one on a hillside above the loch once.
I was wondering if a little local tremor such as the 1997 event might have just been enough to cause a release of methane from the top layers of the sediments? In Urquhart Bay I have often seen the bottom covered with a thin sheet or layer of biological material with little pimples of gas trapped underneath, waiting and growing until they were big enough to rupture the sheet.
Another possible cause of such a release might be unusual seiche activity creating faster than usual currents along the bottom of the loch.
Cheers, Dick. |
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Hi Dick,
I agree that the immense area of disturbed water (described in the Palmer report) was probably caused by the tremor triggered release of the methane gas from the bottom. Alternatively, this kind of surface appearance might have been caused by a sudden and strong gust of wind striking the water. Palmer’s terminology used to describe what he saw is rather vague. An occurrence appearing like a ‘tremendous rushing of the water’ and a ‘turmoil’ (Gould 1969:51) to one person could be perceived less dramatic by another. Lack of precision and a reference to a more objective (i.e. widely known) phenomena make this part of the report almost useless for analysis.
By the way, from your experience, would you reckon that it is possible for debris on the bottom of Urquhart Bay and Dores Bay to be brought up by the accumulated gases to the surface. These being relatively shallow areas where the pressure is not as strong as in the main ‘trough’ and richer in the biomaterial due to the proximity of the river mouths?
Regards,
Alex |
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