10-06-2002 16:55									#61
	Tired of ads?

From memory, the Gibralter Strait (and the rest of the Mediterrainean) are one big subduction zone (that's why it's so deep there, the soon-to-be-former oceanic plate is being driven completly under Europe). While it's not very active at the moment at the Straits, it's still quite active in the center and east, feeding the volcanoes around Italy and causing earthquakes in the Mideast.

The lack of activity may mean that the zone in that region is dead, but given that the African plate is still moving north relative to Eurasia, I personally doubt it. It could be slowly building stress, to be released when something snaps in the future (think San Anreas versus the New Madrid faults for some idea of what I'm talking about). At this point, the African plate is actively rifting, and this may result in additional stress westward in a short time, geologically speaking.

A bridge sounds like a good idea, but I personally wouldn't want to be responsible for the go-ahead.

edit: Oh yeah...a tunnel is right out.
2nd edit: did they have any structural geologists working on this, or just engineers?
3rd edit: It looks like the Straits region may be a transform zone rather than a suduction zone now -- at least looking at the map Kamrat posted.

Last edited by The Mad Monk on 10-06-2002 at 17:26

	10-06-2002 17:28									#62
	Got spare money?

Here's an interesting world tectonic map:

	10-06-2002 18:24									#63
	Inflate your Upload Space

quote: Originally posted by The Mad Monk From memory, the Gibralter Strait (and the rest of the Mediterrainean) are one big subduction zone (that's why it's so deep there, the soon-to-be-former oceanic plate is being driven completly under Europe). While it's not very active at the moment at the Straits, it's still quite active in the center and east, feeding the volcanoes around Italy and causing earthquakes in the Mideast.

It seems that your memory was correct (at least according to NASAīs map)

And Iīm no geologist but IMO the Gibraltar Straits seems pretty safe. Maybe only for the moment but a moment is quite a long period in geological time frame...

quote: The lack of activity may mean that the zone in that region is dead, but given that the African plate is still moving north relative to Eurasia, I personally doubt it. It could be slowly building stress, to be released when something snaps in the future (think San Anreas versus the New Madrid faults for some idea of what I'm talking about). At this point, the African plate is actively rifting, and this may result in additional stress westward in a short time, geologically speaking.

Again the time-span, at the current rate of movement weīre talking hundreds of thousands of years. I think itīs safe to say that the bridge will be geologically safe for at least a couple of thousand years. And in that time the bridge will have crumbled to dust anyway, so...

If we continue present-day plate motions the Atlantic will widen, Africa will collide with Europe closing the Mediterranean, etc. But thatīs like 50 million years from now...

quote: A bridge sounds like a good idea, but I personally wouldn't want to be responsible for the go-ahead.

I donīt think the bridge is a good idea at all, really. For reasons stated in my initial post.

quote: edit: Oh yeah...a tunnel is right out.

Yep, but Iīm mostly worried for the structural integrity of the tunnel. It seems to be an awful lot of water pressing down on it. But then Iīm no building engineer either

quote: 2nd edit: did they have any structural geologists working on this, or just engineers?

I donīt know. Iīve only heard engineers talking about this grand achievment of mankind, etc, etc... But I assume theyīve made a geological survey. Anything else would be stupid (but then again, thatīs capitalism for you )

quote: 3rd edit: It looks like the Straits region may be a transform zone rather than a suduction zone now -- at least looking at the map Kamrat posted.

Nope, Iīd say itīs a subduction zone. NASAīs map is a bit more detailed

	10-06-2002 19:09									#64
	Support Apolyton, buy Galactic Civilizations

Reminds me of the plan to build a bridge from Sicily to Italy. "When they build the bridge" is used on the island the same as "when hell freezes over."

	10-06-2002 23:21									#65
	Lose 30 kilos (of popups)

A tunnel is impossible. I watched a show about where they clearly stated that a tunnel is much too difficult. Too deep, too much pressure. And way to much pollutants building up from vehicles inside the tunnel choking the air.

The bridge is the only real aspect possible. Even tho the 3 of the support columns would have to be the size of the empire state building

	10-06-2002 23:23									#66
	Full PM-box? Change here!

plus once you open a bridge in morrocco, it just becomes a place for yet more refugee's to cross over. Whos gonna pay for the african half? Morrocco? lol

	11-06-2002 00:26									#67
	Support Apolyton, buy Civilization: The Boardgame

So are you for or against a bridge, faded?

	11-06-2002 01:33									#68
	Put an end to popups!

What if you anchor an airtight tube 100 feet below the surface?

	11-06-2002 01:53									#69
	Full PM-box? Change here!

Then you'd have an airtight tube 100 feet below the surface.
getting the cars in might be a pain

	11-06-2002 02:17									#70
	Support Apolyton, buy Call to Power 2

Immortal Wombat, Why?

	11-06-2002 02:20									#71
	Increase Your PM Length

Think about it. If the air cannot get in, how can the cars?

	11-06-2002 02:22									#72
	Support Apolyton, buy GURPS/ Alpha Centauri

quote: Originally posted by Ned What if you anchor an airtight tube 100 feet below the surface?

Nope. We use real units in Europe!

	11-06-2002 02:30									#73
	Help yourself to an AD-FREE life

This thread is merely demonstrating society's intense need for teleportation. Teleportation must be invented as soon as possible, so that projects like this are unnecessary!

	11-06-2002 03:28									#74
	Support Apolyton, buy Civilization III: Complete

quote: Originally posted by Immortal Wombat Think about it. If the air cannot get in, how can the cars?

Airlocks.

Also, run electric trains in the tunnel an carry the cars.

	11-06-2002 04:58									#75
	Support Apolyton, buy Civilization III: Complete

That is how the Channel Tunnel works Ned.

Yeah, it would be quite impressive although I have seen a bridge of a similar length to that proposed (OK, it was part suspension, part causeway, the Vasco De Gama Bridge in Lisbon spanning the Tagus). It is 10 miles long.



The Humber Bridge where I live is pretty impressive too, only drove across it on Sunday Not as long but was until recently the longest single-span suspension bridge in the world.

	11-06-2002 06:56									#76
	Lose 30 kilos (of popups)

NYC's Verinzano is pretty big. Or I could be thinking of one of the other 5 massive bridges into NYC.

The one out to Key-west florida is huge. Like 10 miles or so...I remember driving it when I was a kid (err...riding.not driving)

	11-06-2002 08:15									#77
	Got spare money?

I remember watching a Discovery documentary about this and other ridiculous to insane engineering projects.

The underway geography of the straits (cross section) is like a 'W', except the middle peak is still quite deep. The trenches are extremely deep. Because of this, a tunnel is completely out of the question. A suspension bridge is the only real option, with a middle support built on however many million tonnes of concrete is necessary to reach the middle peak.

Why one would waste time and money on such a thing is beyond me. All it will do is end up being a conduit for illegal immigrants to Europe from all of Africa and serve no other meaningful purpose. I certainly don't envision too many private investors lining up to foot the bill (although they might willingly lend to a government to do such a thing). Besides all that, the bridge would become a very juicy terrorist target - imagine protecting a kilometre deep column of concrete from attack. Hell, they could probably infiltrate the construction crews (sure to be drawn from North Africa and beyond) and plant it during construction for detonation a few months or years into the future. Knowing the EU, they would probably even employ the bin Laden family's construction company as contractors.

	11-06-2002 08:21									#78
	Support Apolyton buy from Amazon

quote: Originally posted by Asher I don't know if it'd be called a chunnel, since it's not a channel it's being dug under, no?

If the water's a thousand meters deep, a tunnel is a silly idea...

	11-06-2002 08:38									#79
	Support Apolyton, pre-order Civilization IV

What's the deepest tunnel that has been built?

	11-06-2002 08:50									#80
	Full PM-box? Change here!

Don't know...

Appears to be the Hitra tunnel in Norway which hits max. depth of 264 m and is 5 645 m long.

	11-06-2002 09:15									#81
	Support Apolyton

1. Does the tunnel feel the pressure of the column of earth above it? (Assuming yes...that would be over a thousand psi. Figuring soil as twice the density of water or more.) Wonder how they shore it.

2. How deep is the chunnel? Didn't realize that it was so shallow over there. But I'm a PAC sailor...

	11-06-2002 09:28									#82
	Support Apolyton, buy Alpha Centauri

2) Average depth of Chunnel = 150 ft, according to eurorail. That probably puts max depth somewhere near 100 m.

1)a) Why column of earth? Hitra is undersea tunnel...

1)b) Probably not. Would feel some increase, but soil acts more like solid than fluid when packed. In other words, it's self-supporting...

	11-06-2002 09:44									#83
	Avatar Enlargement: We've got the solution

Interesting to think about. Wonder what the deepest "under mountain" tunnel is. I guess that would have to be through rock and maybe it is shaped to be self-supporting. Wonder if earth transfers the pressure more than rock.

	11-06-2002 09:53									#84
	Put an end to popups!

The problem isn't just the water, it's also the subduction zone. Imagine the sea floor as a conveyor belt. At the mid-ocean ridges crust is being formed and pushed out to the tune of a couple or a dozen cm a year; this crust spends the next forty million years or so moving under the sea, and then is shoved under a continent and back into the planet at subduction zones.

This process is more or less continuous, and any debris collected on the sea floor during its travel goes down the subduction zone along with it. As a result, not only do you have to deal with the huge water column (because the crust is literally diving into the planet), you have to deal with hundreds or thousands of meters of unconsolidated rock that's slowly being ground into mud below the 'surface' of the trench.

At least until pressure and temperature are such that the mud is either squeezed into rock or melted -- of course, that adds a whole new set of engineering problems...

	11-06-2002 12:23									#85
	Support Apolyton, buy Civilization: The Boardgame

Build it, and keep it closed.

Just to see if we can.

	11-06-2002 12:36									#86
	Browse Apolyton AD-FREE

Provost: The Akashi-Kaikyo Bridge, connecting Kobe on the mainland with Awaji on Awaji Island, will be a huge three-span cable-stayed bridge some 3910 meters in total length with a center span of 1990 meters. When completed, it will be the longest bridge of its type in the world, surpassing the Humber Bridge in the U.K......but I guess you knew that already?

Attachment: a-k2.jpg
This has been downloaded 13 time(s).