I have been asked to post the following by Alan Speight, who is not registered on this forum but is concerned that this information is made widely available.

On Monday 9th February there was a magnitude 2 earthquake centred on Kirkby Lonsdale just before midday. It was felt as it happened by a well known caver in Lost Johns' Cave where it sounded like an explosion (possibly because of a falling rock nearby). It is possible that this earthquake may in some way have been part of the reason why the fatal accident happened in Bull Pot, Kingsdale. The latter is a friendly cave which many people visit; there are many other similar systems around the Dales and Alan feels it's important that cavers in general look around for anything which may have changed underground elsewhere.

The possibility of earthquake involvement in rockfalls has been discussed previously on this forum but awareness of this is still not especially great among the caving community. The British Geological Survey (BGS) website monitors earthquakes and records these on its website very soon after they have happened.

On a personal note, I'd like to add my condolences to the family of the victim of this tragic accident and to his friends in the YSS (a kindred club to my own).

Pitlamp said:

The possibility of earthquake involvement in rockfalls has been discussed previously on this forum but awareness of this is still not especially great among the caving community.

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Thank you for that John. I wonder whether something to this effect can be postered in Inglesport/Bernies so people are mindful to be wary - if popular venues are being visited it is very very easy to be complacent that everything is OK and "business as normal", when actually it would be wise to be vigilant and specifically look for fractures/cracks and instability at, and below, pitch heads and arched passages etc..

That's a very good suggestions Chris. I'm unable to get to Ingleton today but perhaps someone who reads this forum can sort something out? (The Penyghent Caf? at Horton also springs to mind, as groups visiting the Birkwith caves and Long Churn sometimes congregate there.)

As a matter of interest last weekend there were CDG members diving in Keld Head and they reported good visibility. I did two long dives in there on Tuesday and Thursday this week and I was surprised and disappointed by the unexpectedly hazy water (which was much worse than could have been caused by caving traffic in the KMC). I'm beginning to wonder if Monday's earthquake shook loads of sediment off ledges in there. I noticed the same effect at Malham Cove Rising a while ago following a small earthquake.

There's no doubt that earth tremors do move things around; "braveduck" who posts on here has been watching these for a long time and it was him that first alerted me to the potential effects. We all need to be careful.

Sorry about deviating from the original topic, maybe we should be encouraging people to check out this site at the same time as checking the weather;

http://www.earthquakes.bgs.ac.uk/earthquakes/recent_uk_events.html

Especially in view of this potential development: http://www.thewestmorlandgazette.co.uk/news/10886192.South_Lakes_fracking_threat_raises_alarm/

There is most definitely a need to watch out for movement. There are at least 3 caves in my area of the South Peak that have 'moved'. In one the roof of the 'terminal' chamber which had passages leading off on the far side was seen to have dropped and stopped any further progress a few years ago. In another cave which I had been visiting for over 20 years a jumble of rocks which you had to climb down had re-arranged themselves slightly.

In 2007, in Darfar Pot, we were looking at enlarging a pitch down into a new section of cave. I remember inspecting the 'roof' of it and although it was comprised of large boulders, it 'looked' safe. We went back the next week after a small tremor had been reported in the Manchester area and sections of the 'roof' had dropped into the top of the pitch, blocking it!

Very scary. Took some effort to re-open it, but we did end up winning the 200m rope H&H compo that year due to our efforts. Take care, be observant.

There was a substantial amount of movement in Engine vein at Alderley Edge a few years after a small quake which if I remember rightly caused little or no damage on the surface.

I wonder if someone at BGS would be interested in all this anecdotal evidence, if it can be related to any particular seismic event?

It could give an indication that the underground environment is possibly more susceptable to tremors and minor 'quakes', indicating that even if fracking does not cause earth movement, earth movement could threaten the integrity of the fracking 'safety' measures ---

I think effects may vary according to intensity in some areas.  We were very worried about stability of boulder chokes in Meghalaya as it has regular earthquakes high on the Richter scale.  Someone suggested the possibility that a regular shaking actually "settles" the contents of a choke - making them slightly more stable... just speculation of course..

cavermark said:

I think effects may vary according to intensity in some areas.  We were very worried about stability of boulder chokes in Meghalaya as it has regular earthquakes high on the Richter scale.  Someone suggested the possibility that a regular shaking actually "settles" the contents of a choke - making them slightly more stable... just speculation of course..

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Sounds sensible to me, the more you shake a bucket of sand the less it settles.

It would also suggest the UK is probably more susceptible to rock fall.

I would agree with the 'regular shaking' theory.

The point I would suggest is that the UK tremors are not big enough to settle anything, but big enough to loosen and disturb substrata, a far more worrying scenario, they could destabilise and weaken an area that may not 'settle' until some time afterwards, this is what this anecdotal evidence could clarify.

^^ sounds reasonable.

A big quake will also bring down stalactite formations. There are some massive ones on the floor in Reservoir Hole. There has been a tendency to attribute these to frost shattering (there are several similar locations on Mendip) but after visiting New Zealand and seeing identical looking fractures in stal, and talking to a geo physicist, I am sure the damage was done by an earthquake or quakes. Mind you we are probably talking about much larger quakes than are usually experienced in Britain but over tens of thousands of years I am sure there have been plenty.  Slightly off topic is that when we were originally digging there people would periodically hear a loud rumbling which was quite disturbing and suggested a large loose chamber up ahead. However once in the Frozen Deep we would continue to hear the noise and realised it was usually the same time of day. Further enquiries elicited the fact that a quarry some miles away was being blasted at that time. Sound travels a long way underground.

I don't know how far you can go back with this, but there were two earthquakes in the 13th century that were strong enough to severely damage/destroy churches in the Mendips region....

I do remember some neatly severed straw columns in a 6" bedding in Black Rabbit, we attributed that to blasting in the neighbouring quarry dislocating the beddings, they were all snapped at about the same level and displaced by about the same distance, maybe 'kinks' in other columns could be attributed to siesmic activity? (maybe dating evidence?)

The damage we have seen is probably older than this. However more recent tremors such as those probably accounts for the broken straws scattered about the cave which are lying on mud and quite loose. In fact when we first found the chamber it looked for all the world as though the damage had been caused by an individual or individuals wandering about. I suppose some of it could be the action of clumsy bats!

If you check out other pages on that BGS link, they list significant UK earthquakes over the past few centuries, maybe some clues there? (I think the cut-off is Richter 5)

bograt said:

Sorry about deviating from the original topic, maybe we should be encouraging people to check out this site at the same time as checking the weather;

http://www.earthquakes.bgs.ac.uk/earthquakes/recent_uk_events.html

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You have shared here a very useful resource Terry thank you....

I'm sure there are more out there, we can't all search everything!

Thanks Richard.

Hmm, can't understand the movement of this thread to 'Yorkshire', would have thought it relevant to everyone, especially thinking of the constructive responses from other areas?