Earthquake, Mag 2.7, 4km north of Bryn Eglwys

alanw

Active member
Also 4km W of Corris Uchaf


DATE24/09/2026
ORIGIN TIME15:00:58.8 UTC
LOCATION 52.663 -3.913
DEPTH14 km
MAGNITUDE 2.7
LOCALITYTALYLLYN,GWYNEDD

 
Ooh, will be interesting to know if any underground changes have occurred...

Chris.
 
There was a similar one of Mag. 2.7 in Silverdale, Morecambe Bay a few days ago


"Felt in Silverdale, Carnforth, Grange-over-Sands, Milnthorpe and surrounding villages mainly from around 15 km from the epicentre. Typical reports described, "loud boom with weak shaking for a couple of seconds", "like a really strong explosion that rattled the doors and windows" and "sounded like a lorry crashing into the house"."
 
We went into Bryneglwys 10C adit yesterday. There was a load of rock fall near the first chamber which has made the walkway a bit perilous. There was cracking sounds and a a bit of the roof delaminated and fell into the darkness below. We didn’t hang around and got the hell out of there.
Ooh, will be interesting to know if any underground changes have occurred...

Chris.
As above Chris
 
We went into Bryneglwys 10C adit yesterday. There was a load of rock fall near the first chamber which has made the walkway a bit perilous. There was cracking sounds and a a bit of the roof delaminated and fell into the darkness below. We didn’t hang around and got the hell out of there.

As above Chris

Is the fall next to a wire fence? If so its been like that for awhile.
 
A minor aftershock, a minute and a half after the first, this time less than a km from Corris Uchaf.
Low intensity quakes sometimes take a while to be analysed.


DATE24/09/2026
ORIGIN TIME15:02:33.7 UTC
LOCATION 52.665 -3.875
DEPTH16 km
MAGNITUDE 1.0
LOCALITYTALYLLYN,GWYNEDD
 
Ooh, will be interesting to know if any underground changes have occurred...

Chris.
Yes - both here and on UKC there are regular posts about recorded tremors. What we don't get much of, if any, are any hints of correlation with changes underground - much speculation, of course. I suppose you would need to be able to correlate by fairly close timing, and see a pattern emerging. It would be a long-term project for a very patient person. I have always been a bit of a sceptic over whether the low level tremors have much effect. I think the simple deterioration of rock, and props etc over time are are much more significant factor. A tremor could simply be the trigger for something that would otherwise have happened in a few month's time anyway. I imagine the few working mines we have do keep records both of tremors and ground movement. Whether there is a correlation there only the mine engineers would know.
 
Bryneglwys

I was at the waterfall pit (Floor 25, Ch 9B?) on Tuesday and didn't spot any changes there.

Today (Sun 4 th Oct) I went for a look underground. I did the Floor 10C to Daylight Adit through trip and honestly didn't see any new falls. The last time I did this route was almost exactly a year ago and the first time that I went this way was in 2003. There has always been a fall across the haulage ledge on Floor 10C, two chambers in (where there are big, old bolts, which I think JSMTC Tywyn installed for an abseil.) It didn't seem any different and the rocks looked dirty and not clean, like a fresh fall. I'm sorry: I now realise that I should have taken some photos for people to see.

The handline down Chamber 12C is still there, as is the rigging for the 50m pull-through abseil. My main point of concern was between Floor 15C and Floor 20 in chambers 10C & 11C. There are big roof-fall blocks, with a lot of pyrite in them, that you scramble over. I've seen new falls in this area, over the decades but nothing seems to have changed here recently. A block might have recently come down and hit the catwalk chain that goes out left rom where the fixed rope starts.

Floor 20 was waist-deep in water behind the pebble damn. The water here always seems colder any other mine or river I've been in! The crawl under the collapsed rails was another area of concern but this looks unchanged too. The waterfall down the Main Shaft was thundering and the Daylight Adit was about its usual water level. There still ripe blackberries outside.

I also walked along Floor 15B, which I've visited fewer times. I couldn't see any fresh falls in the tunnel or in the parts of the chambers that I could get into. I'd left my bolt hangers at home and so I didn't go down the pitch to Floor 25 (Two 10mm plates required: nuts & washers in-situ).
 
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