Trig Gledhill
New member
As previously stated, we was none the wiser down in Gilwern Passage, Draenen
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Earthquake in Swansea Valley
- Thread starter ptpeaty
- Start date
He said: ?There was huge rumbling which was ongoing for at least 10 seconds and we thought that there had been a cave-in.AWW said:Looks like someone shat themselves underground. linky
?A few minutes after that there was an awful smell like rotten eggs which usually means there has been some rock movement.
?We had a quick look around in the immediate area and decided everything was OK and carried on with our trip.
?We were totally oblivious to what had really happened.?
<<The quake was the biggest event in the area since a 5.2 magnitude earthquake in 1906.>>
cap n chris
Well-known member
rhychydwr1
Active member
I was at Penwyllt. and did not feel a thing.
Graigwen
Active member
Minion said:AWW said:Looks like someone shat themselves underground. linky
What a farcical article! It reads like something you?d find in the Sunday Sport, right next to the story about a bloke burning his penis on a Greggs pasty and a story about a London bus being found on the moon...
They were in OFD, the same cave where Aber CC were in Edward's Shortcut at the time of the quake and noticed nothing!
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mrodoc
Well-known member
I know people who have been underground in a boulder choke in an earthquake (not UK) and just noticed some gravel falling. When we were digging in Reservoir Hole we periodically heard rumbling in the distance and assumed boulders were falling in some big chamber ahead. When we reached the big chamber the sound was heard again (sounded like a tomb door shuttingin the far distance) and at that point we thought of quarrying. This seems to be the explanation - shock waves from blasting carried several miles through rock.
Cap'n Chris said:AWW said:Looks like someone shat themselves underground. linky
How so?
The article is correct: crushed or cracked limestone often releases H2S odour. Thought every caver knew that.
Can't say I've ever noticed it. There is a particular smell to a bashed limestone rock but nothing as gagginly awful as a rotten egg. Maybe the rocks you're familiar with have sulfide inclusions.
I think that it's far more likely that the cavers in question heard the result of the p-wave propagating from the rock into the open passage as a sound wave and one of them promptly filled his wellies.
ZombieCake
Well-known member
Maybe H2S is a Mendip thing, or maybe the finer confines of a Mendip cave concentrate it? The rock does seem to aromatically retaliate to creative landscaping.
Stuart France
Active member
ZombieCake said:
H2S from broken rocks in areas with big caves is bit off the earthquake topic, but it is a fact. Break a bit of rock in an area with big caves and you can likely smell it for a few moments on the newly exposed surfaces. Not just Mendip but South Wales too. So is this bad-egg-gas rock phenomenon a marker for places in which to discover big caves? Do Yorkshire and Derbyshire pong too?
The late Clive Jones (former SWCC member and the brains behind their 'Greensites' cave-discovery-by-technological-means project) once suggested to me that "bugs make caves". He was alluding to limestone rock with a high sulphur content, from ancient organisms presumably, may produce sulphurous acid by various chemical reactions involving water and CO2 which more readily dissolved the very rock itself (thus making cavities within sulphurous rock strata) than other kinds of limestones with low sulphur content.
I'm not suggesting for a moment that anyone should set up a geological mapping project to "break rocks and then sniff" to identify areas having speleogenetic potential.
But there must be a PhD in this for someone and then a career as the world's first professor of speleochemistry. Unless you know better.
Saturday's Earthquake
We have received the following report from Brecon Beacons National Park Authority, who will be carrying out appropriate checks - but Members should be alert to the possibility of rock movements affecting caves and slabs. Particularly vulnerable areas could include the the approaches and interior of Porth yr Ogof (including the roof slab of the Great Bedding Cave), the Gunpowder Works remains and some sections of roof within the silica mines behind Dinas Rock, as well as loose rock at Dinas Rock, Cribarth and Penwyllt and other locations further afield where individual rocks were 'near-critical'. Please make appropriate assessments and exercise due caution in these and other vulnerable areas.
SWOAPG
We have received the following report from Brecon Beacons National Park Authority, who will be carrying out appropriate checks - but Members should be alert to the possibility of rock movements affecting caves and slabs. Particularly vulnerable areas could include the the approaches and interior of Porth yr Ogof (including the roof slab of the Great Bedding Cave), the Gunpowder Works remains and some sections of roof within the silica mines behind Dinas Rock, as well as loose rock at Dinas Rock, Cribarth and Penwyllt and other locations further afield where individual rocks were 'near-critical'. Please make appropriate assessments and exercise due caution in these and other vulnerable areas.
SWOAPG
Graigwen
Active member
Not limestone, but when chip sampling some rock lines on Mynydd Sygun, Gwynedd, I was accompanied for two days by the smell of sulfur dioxide. Often the force of a hammer blow would could the rock to burn for a second or two owing to the high sulfur content. (The sulfur was of volcanic not biological origin.)
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