Messines mines

[haworthnick]

A question just came to me; DId the mine explosions at messines ridge register on the rickter scale or was this not in operation in 1917.

Many thanks in anticipation

Nick

[Fattyowls]

Nick

Excellent question. The scale was developed by Charles Richter and Beno Gutenberg at CalTech in 1935. I've seen tables of the scale which use TNT equivalent as a comparison so we could possibly work it out. It's also possible to find examples of different magnitudes which describe the effects such as shaking which could be related to reports of the event. I know that the Ontario Farm mine didn't create a crater but may have caused the earth above it to liquify which is a common effect in large earthquakes. There are reports of the mine site bubbling for some time after the detonation. I might try to work out what it would have registered after a really strong cup of coffee tomorrow but I can't promise anything.

Regards,

Pete.

[haworthnick]

Thanks. It was just one of those questions that popped into my head. I'd not heard of liquefaction in terms of the messines ridge mines . I've heard of it in describing earthquakes. Is it to do with water content of the local geology? Nick

Thanks. It was just one of those questions that popped into my head. I'd not heard of liquefaction in terms of the messines ridge mines . I've heard of it in describing earthquakes. Is it to do with water content of the local geology? Nick

[Fattyowls]

Nick

You've probably not heard of liquefaction in relation to Messines because it's only just occured to me and may be complete rubbish. You are quite right about the water content of the soil in relation to the process. I think the Ontario Farm mine had to be cut deeper than those further north as the geology above it was a damp former alluvial deposit; I believe that the site is now a shallow pond in the farmyard. I keep meaning to go and have a look from the road but haven't managed it yet. I'm intrigued myself because I can't remember where I read about the bubbling, it might have been in Ian Passingham's "Pillars of Fire" which describes the Messines operation.

I'm still thinking about what Messines would have registered on the Richter scale; 5.0 is a rough guess at the moment but it's complicated by the distance between Hill 60 in the north and Factory Farm and Trench 122 in the south and the fact that they didn't go off at exactly the same time. Probably needs another cup of coffee.

Pete.

[haworthnick]

This may show my misunderstanding of plate tectonics but surely the explosions along a line will be similar to that of friction between 2 plates or 2plates colliding against each other which is an earthquake isn't it?

Nick

[Fattyowls]

Nick

Yet another good question. I'm starting to wonder if I might have been asleep in that lecture that dealt with plate tectonics and the relationship to earthquake epicentres all those years ago. You are right about earthquakes being caused by plates pushing or rubbing against each other. The boundary doesn't move for years and the stress builds up until the junction snaps causing shock waves. It is possible to get earthquakes away from plate boundaries where normal faults move quickly. These tend to be much smaller in magnitude; I've experienced two in this country and both were just a gentle shaking. It's amazing how much I've forgotten or more likely didn't know in the first place; it's been quite nostalgic reading about p and s waves and focuses and epicentres.

Pete.

[Herekawe]

Thought I read somewhere in the past that the Ontario Mine was an experiment with a different type of explosive not a "lifting" explosive that left a big crater and was a danger to the attacking troops as pieces of rubble fell on them - as per Lone Tree Crater - but none the less destroyed anything near it via the initial shock and heat which as you point out caused the ground to bubble like porridge. Most unpleasant. I believe people in Lille did think the explosions of the 7th June 17 were an earthquake initially and either that or the shock blew out most of the windows in town. Once again I don't have a reference to hand.

[Fattyowls]

Herekawe

I am going to have to look around for some more information on the Ontario Farm Mine; I think that it was only completed hours before the attack. as I said it the surface geology above it was completely different from most if not all of the other mines. One of my Auckland footballers was killed in the attack on the ridge and his name is on the Memorial to the Missing on the base of the windmill so the area is of particular interest. I also think of the tons of ammonal that are still underneath Le Petit Douvre Farm every time I pass it on the way up to the village. While I was doing the trip down academic memory lane in the earthquake literature I read something that said if something makes the earth shake it's an earthquake so I can see it from the point of view of the inhabitants of Lille.

Pete

[haworthnick]

Many thanks,

Here's another ponderable in the mix, how far up and down the line would the effect of the mine explosions been felt, or would the immediate have been swamped with artillery explosions so germans would not have felt anything untoward, whereas people further away (Lille) would have ben more aware of something different.

Nick

[centurion]

Plates constantly rub against each other as one is forced under another. An earthquake is usually created when they don't rub but stick so pressure builds up and up and then something gives and all that accumulated energy is released at once instead of as part of a gradual and continuous process.

Much of the energy from the Messines and Somme mines would have been dispersed upwards whereas in an earhquake it tends to be transmitted horizontally.

[haworthnick]

Thank you for that, I suppose there is human "deep" and geologically "deep" as well

Nick

[centurion]

Nick

You've probably not heard of liquefaction in relation to Messines because it's only just occured to me and may be complete rubbish. You are quite right about the water content of the soil in relation to the process. I think the Ontario Farm mine had to be cut deeper than those further north as the geology above it was a damp former alluvial deposit; I believe that the site is now a shallow pond in the farmyard. I keep meaning to go and have a look from the road

This the one?

[centurion]

This crater is bigger and deeper

[haworthnick]

Wonderful pictures, happy memories of doing the Messines ridge walk from Whitesheet to Messines and getting heat stroke half way through, I seemed to remember Lone Pine Cem needed a lot of tlc at that point, I think we reported to the CWGC in Ypres when we got back.

Nick

[centurion]

happy memories of doing the Messines ridge walk from Whitesheet to Messines and getting heat stroke half way through,

No danger of that this week. Even with the sun the wind was PD Cold!

[Fattyowls]

This the one?

Centurion, I think that's Peckham if the spire above the farm buildings is Wytschaete church. The Peace Pool would have been behind you and Spanbroekmolen British Cemetery over to your right. Bear with me while I put some maps together to try and illustrate the Ontario Farm theory and see if I can see any photos using the forum search.

No danger of that this week. Even with the sun the wind was PD Cold!

Did you have any medicinal compound to insulate you against the chill breezes?

[Fattyowls]

If I'm reading the map of the Messines attack correctly the attached photos show Ontario Farm. I've lifted these from Google Maps and I wonder if the depression in the farmyard is caused by the mine. The shape doesn't look completely concentric and I am wondering if some of the depression outside the farmyard has been filled in or ploughed away. I've had a search of the forum and it would appear photos have been posted but I haven't been able to open them. Can anyone oblige with an Ontario farmyard photo?

Pete.

[Herekawe]

As an aside - as someone who works with soils and drainage a fair bit - albeit in NZ it has interested me over the years how some craters, like Peckham and Lone Tree as above are full of water, even through the are on the tops of ridges. Other craters in Belgium lower altitude I expect to be flooded as we are not high above sea level. I think the water must press up from underneath, the rainfall and topography wouldn't fill Lone Tree, that is insufficient rain and a very small catchment area. And if water from underneath fills Lone Tree and sufficient pressure to do this, why aren't Peckham and other lower craters constantly overflowing as they are lower again? Perhaps they are but I have just never noticed the drains.

Unrelated because obviously different soils the big crater on the Somme - Lochnagar which is in a valley is dry but the small crater in High Wood is full of water and on top of the ridge? Its catchment is only very small so I don't think rain would do it.+

J

[Fattyowls]

Many thanks,

Here's another ponderable in the mix, how far up and down the line would the effect of the mine explosions been felt, or would the immediate have been swamped with artillery explosions so germans would not have felt anything untoward, whereas people further away (Lille) would have ben more aware of something different.

Nick

Nick

I've got hold of a copy of Ian Passingham's "Pillars of Fire" from the library; I'll read the relevant sections and some other stuff I've got and try and work out what was felt, heard and seen and where.

As an aside - as someone who works with soils and drainage a fair bit - albeit in NZ it has interested me over the years how some craters, like Peckham and Lone Tree as above are full of water, even through the are on the tops of ridges. Other craters in Belgium lower altitude I expect to be flooded as we are not high above sea level. I think the water must press up from underneath, the rainfall and topography wouldn't fill Lone Tree, that is insufficient rain and a very small catchment area. And if water from underneath fills Lone Tree and sufficient pressure to do this, why aren't Peckham and other lower craters constantly overflowing as they are lower again? Perhaps they are but I have just never noticed the drains.

Unrelated because obviously different soils the big crater on the Somme - Lochnagar which is in a valley is dry but the small crater in High Wood is full of water and on top of the ridge? Its catchment is only very small so I don't think rain would do it.+

J

J

I've got some stuff that may help answer the question; let me do a bit of reading and scanning and post something later. By the way in Ian Passingham's "Pillars of Fire" it is stated that the Ontario Farm mine was 60,000 lbs of ammonal and as I thought only completed on the 6th June 1917. Ammonal only was used at Spanbroekmolen, St Eloi and the Caterpillar to the north and all of the mines down to Factory Farm (Trench 122) to the south. The others were predominantly ammonal with either gun cotton or I think blasting powder (bla. in the book). I'd be intrigued to see if we could find your experimental explosive source.

Pete.

[Peter and Ellen]

Two comments if I may,

1. It is my understanding that water does not pass through the blue clay, Therefore, I would conclude that the water does not come from below. At Spanbroekmolen, the water lever drops up to, around 600mm, during a long hot summer and then, refills during the winter. My conclusion is that it is rainfall. When it rains up there, you get torrential downpours. Also, there must be a drain at this crater, as the infrastructure at the site, is never threatened by the rising water level during winter. It seems to me that it has a maximum water height. Don't mind being corrected on my thoughts.

2. I suspect the bubbling just after being blown, is the residual heat left from the blast.

Regards, Peter

[haworthnick]

Nick

I've got hold of a copy of Ian Passingham's "Pillars of Fire" from the library; I'll read the relevant sections and some other stuff I've got and try and work out what was felt, heard and seen and where.

J

I've got some stuff that may help answer the question; let me do a bit of reading and scanning and post something later. By the way in Ian Passingham's "Pillars of Fire" it is stated that the Ontario Farm mine was 60,000 lbs of ammonal and as I thought only completed on the 6th June 1917. Ammonal only was used at Spanbroekmolen, St Eloi and the Caterpillar to the north and all of the mines down to Factory Farm (Trench 122) to the south. The others were predominantly ammonal with either gun cotton or I think blasting powder (bla. in the book). I'd be intrigued to see if we could find your experimental explosive source.

Pete.

Many thanks, for this, it's turning into a very interesting thread not bad for a random thought that occurred to me at 11oclock at night when I was just about to go to bed.

Nick

[Fattyowls]

Nick

Sometimes the random thoughts are the best ones; it's certainly made me look at the operation in a whole new light.

The sequence of events if I'm reading Ian Passingham's narrative correctly was that at 3.00 am the barrage stopped. There was relative silence until 3.09.53 when the two southernmost groups at Trench 127 and Trench 122/Factory Farn exploded, four mines in all. There was a gap of 7 seconds and then the remaining fifteen mines in eleven locations went off in 12 seconds. The time lapse from first to last was 19 seconds and a wave like accoustic effect was reported. It was reported that the firing party at the Hill 60/Caterpillar pair of mines heard the rumble from the early detonation to the south as they fired their mine.The barrage from 2,226 guns immediately opened on the frontage from Hill 60 to St Yves covering the German lines to a depth of 700 yards. The word earthquake is frequent in the descriptions. It certainly makes me think of the phrase "all hell being let loose"; particularly as red was the predominant colour in the descriptions of the pillars of fire.

One correction to the above; the bla. is not blasting powder as I first thought but blastine.

Pete.

P.S. On the subject of descriptions which mention earthquakes a random thought occured to me late last night. Would the only group of people able to compare the effect of the mines to a geological earthquake be the NZ troops having maybe experienced them back home? J (Herekawe) or any of the NZ contingent might be able to enlighten me. Having said that I think they probably had other things on their mind as they clambered out of the trenches.

[haworthnick]

Many thanks for that, I think it was in Peter BArton's book Passchendaele who theorises that because there was a chain of explosions rather than one simultaneous one this probably increased the disorientation of the German troops as these explosions were going off all around them and they could whiteness this.

Nick

[Fattyowls]

Pete, J

In response to your post and J's earlier questions I've found a good diagram in Geology of the Western Front 1914-1918 by Peter Doyle (Geologists Association Guide No. 61, 1998) of some of the Messines Mines which I'm attaching.

I'd not thought of the heat of the explosion at Ontario Farm; there is a description of the site being like gloopy porridge coming slowly to the boil. I can see that contributing but since the site is described as bubbling for days I'm wondering if the explosion lifted the moist alluvium and dropped it back into the whole trapping large amounts of initially hot air. Pillars of Fire reproduces a table from Mining in France by Maj-Gen R N Harvey which shows that the Ontario farm Mine created a rim only 10 feet wide compared to the largest rims which were the Petit Bois pair where the rims were 100 feet. This suggests to me that most of the debris lifted by the explosion dropped back in situ. I think my shockwave liquifaction theory is at best not proven; certainly the pill boxes at the NZ Memorial which are the closest I can think of to Ontario Farm looked stubbornly horizontal and and not sunken when I was there in September.

With regard to the water in Spanbroekmolen I think the water table above the wet Kemmel Sands layer is probably the controlling factor given how far above the blue Ypres clay the crater is, I wonder if the level is also controlled by the dry Whytschaete sands around the rim allowing excess water to soak away. However what you describe looks very like the situation at Hollandscheschuur Farm on the diagram. Each one seems slightly different; maybe someone should do a Phd. thesis on it. I think I had better stop at this point before this post turns into it.

Regards,

Pete.

P.S. I think I've got something on J's question about Lochnagar and the High Wood craters; I'll post it separately.

[Herekawe]

Very interesting thread. I am taking it as the non lifting explosive myth is busted only thing I regret is not remembering who told me about that - and I must have told another 50 people over the last 25 years!

The drawing seems fairly obvious Ontario is on a deep bed of homogenous soil - possibly would have adsorbed part of the shock and allowed the rubble to fall back into the hole. I am pretty sure you would be safe as far away as the NZ bunkers - there is that little bunker on the edge of Spanboekmolen which doesn't appear physical destroyed although it was covered with rubble and the people in it killed I believe.

You may be right Fattyowls about the soil around the crater rim and Pete your observations are interesting also about the water levels going up and down. Explosions of this size must have cracked and fissured the soil allowing water freer movement of 100s of feet under the ground vertically but also horizontally.

Given that the rainfall is only about 700mm (bone dry by Taranaki standards) and its pretty evenly spread on average, the catchment is small and I cannot see that water loss to atmosphere would be that great I would have though the water level would be reasonably constant. So I am still not abandoning the idea of subterranean water movements as well.

I think I have seen on the Forum pictures of Peckham drained post war, it would be interesting to know how quickly the craters fill after blasting and again if it was drained. After all they were blown in what would be the driest months?

Another picture of Spanbroekmolen in July - was hot and I was tempted to jump in myself!

James