Official Luthiers Forum!

Some time ago, amongst other academics, I was approached by the staff at the UN for advice on earthquake prediction following the Indonesian quake and tsunami. Those of you that have looked at my biography will know that my speciality is deep crustal structures, specifically major fault zones like the subduction zone off Sumatra. I advised that before any predictions could even be contemplated that a greater understanding of the detailed structure must be obtained. This is a difficult process, ascertaining the nature of the subduction zone 10-30km below the surface is not an easy one. Luckily the oil industry has been carrying out such surveys, usually only to 10km depth or so offshore in sedimentary basins, for a number of years so the base technology is well known.

In my own research I use a system known as ‘3-D seismic tomography’ which basically involves setting of large explosions, or often at sea using large compressed air guns, to send shock waves through the ground which are then reflected back to a 5km or so array of geophones towed behind the boat. Variation in the return time for the shock waves indicates changes in the velocity of the waves within the rocks, changes of velocity indicating changes in the nature of the rock and its possible structure. Many thousands of explosions have to be made while travelling along grids. The amount of data produced is mind-boggling and requires incredible computing power (a Cray) to analyse. When analysed a 3-D image is produced of the probable structure of the rocks. Well that’s the theory!

Following the second major quake further along the subduction zone, and the likelihood of more to follow, it became urgent that the nature of the fault was ascertained particularly as the first quake produced a tsunami and the second did not. What was the difference in the shape and nature of the two areas that caused one to produce the tsunami and not the second? These are questions that need urgent answers.

A seismic survey ship has been hired from the oil industry (at a cost of about $40k per day!) and is now setting off to the area and I have been asked to go and supervise the collection and analysis of the data on behalf of the UN and the British Geological Survey. I fly off to South Africa to meet the boat on Monday. The data collection should take 6-8 weeks if the weather is kind so I’ll be off forum for a while.

I thought I ought to tell you all what is happening as you were all so generous in your efforts to raise money for the Tsunami victims back in January.

Talk to you all on my return.

Colin

PS My Secretary is under instruction that her main task while I’m away is the securing of the Cuban Mahogany bench tops!


PPS Lance, I'll try to upload that MP3 before I go.Colin S38450.2318055556

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Good luck Colin, and be careful, there were two more quakes a few clicks south of Nias last night. A 5.8 and a 5.0. with a couple of after shocks this morning. Wouldn't get me anywhere near the place.

Good luck, Colin...sounds like a fantastic assignment. I'll be looking forward to seeing your published data.

BTW, send me your secretary's address so I can tell her where to send the counter tops!!!

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JJ
Napa, CA
http://www.DonohueGuitars.com

Colin, personally I would consider it an honor to be selected to a position such as this. You must be at the very top of your field.

Good luck, be careful and I hope you are able to compile enough information to give folks a warning next time!

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Dave Rector
Rector Guitars

Colin,

Congratulations, that is a very high honor to be selected for such an important job. If you have internet access, stop by and tell us how it is going.

Best of luck to you, and your secretary!

Jeff

Colin,

What an excellent thing to be called to. How incredible to be supervising such important research - it must feel great to be approached for this, but it must also be something of a weight on your shoulders due to the urgency of the matter. I have no doubt you will make an incredible difference, and I truly hope you're all able to help through figuring out this fault.

Nature is a wonderous thing. Gentle, beautiful and serene - yet at times terrifying, powerful and disasterous. You're doing a great thing, and I believe it is your thoughtful and un-arrogant approach/attitude that will both protect you and produce helpful results.

But just in case there is a tsunami, bring along a surfboard (anyone hear about the guy on vacation that rode the white water from the tsunami into the hotel restraunt where he was staying?)

I'm really looking forward to hearing all about it upon your return!

Best wishes,
Joshua

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Instagram: @jfrenchluthier
Web: https://www.jfrenchguitars.com/

Colin--you will be missed. If there is a computer on board, and if you are able, log in from time to time and tell us what's going on. Best of luck to you and to your assistant. (Bench wood!)

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Thanks for all your kind words. I can predict earthquakes fairly accurately, in as much as I can tell you there will be one, unfortunately I can't, and nor can anyone, tell you when or how big. That's the problem and even afer this works they will still be the same unanswered questions. What we hope to be able to do is to say what type of quake is 'probable' from any given area. The one that precipitated the Tsunami was caused by the rebound of the 'hanging wall' overlying section,(that is the rocks above the fault that have been dragged down by the friction of the moving underlying plate) moving back to their natural position. This caused the sea bed to rise and displace the water catastophically. The second quake, that did not cause a major tsunami, happened when the underlying plate moved following the release of the strain from the first quake. If we can pinpoint areas that are subject to the first kind of deformational rebound then we may be able to model the effects of major quakes in those areas and advise on coastal protection methods like the raised buildings that are now common on the Hawiian coast. We may also be able to more accurately target the tsunami warning system that is now being developed for the area on the lines of the one already operational in the Pacific.

What ever we shall have gained some knowledge, but this is at the cutting edge of the technology and has never been attempted before on this scale (mainly due to never having enough money!) so the outcome is not predictable but we live in hope.

Now where did I put that little plywood travel guitar?

Colin

PS there aren't that many people doing deep crustal seismic tomography so they weren't exactly spoilt for choice on someone to run the operation!Colin S38451.225462963

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.