DISC 15 Copenhagen (2 June)

The Copenhagen DISC was a bit different.  Where we have been seeing class sizes from 20-50 across Europe, here we had just 5.  Maybe an advertising problem, or a repercussion of the SEG taking over the entire DISC program when it had been a joint SEG/EAGE program in previous years.  However, we had a great conference-style room in the amazing Bella Sky hotel and the small group allowed us to be very informal.

About town

Copenhagen in June still required several layers of clothing.  Many outdoor cafes had heaters and blankets, but they lacked the shoulder-height glass windbreaks I saw in Stavanger.  Food at places along the canal was excellent.  My hotel (Bella Sky) was another matter.  This is a big hotel attached to the conference center with 800 rooms, but the cafe menu has a total of two sandwiches and maybe six main courses. If you stay here a week, it is easy to get tired of that menu.  One night I came in late and needed dinner in the room.  I checked the room service menu and found the two sandwiches and six mains, all with meat.  Well, I eat seafood or vegetarian and this was a dilemma. Ultimately I ordered the chicken and bacon sandwich, hold the chicken and bacon.  Not much of a sandwich and it took 1.5 hours to get there.  It is a beautiful hotel, but come on.

Hotel issues aside, I found old Copenhagen charming.  There were some good bookshops too.  I bought a couple of crazy books from the 1930s by Dennis Wheatly, the titles being Murder off Miami and Who killed Robert Prentice? (info here).

More bikes than cars in Copenhagen.

17th Century observatory tower with interior spiral ramp.

Fun Sercel party at the Carlsberg brewery.  Jim Gaiser with old beer truck.

This was my favorite.

DISC 14 Stavanger (31 May)

We had an excellent DISC in Stavanger with 41 in attendance.  The venue was a nice lecture room at the University of Stavanger (that seemed like a good school).  In the audience was my friend Rian de Jong of Shell whom I met years ago on a consulting trip to Oman.  Back then, he and friends took me on a weekend jaunt along the coast road south of Muscat, then up into the high country to look at wadis and ancient villages.  Rian's hobby is jetting around the world to see total solar eclipses.  He put me on to NASA's Fred Espenak,  the utmost guru on such thins... have a look.

Anyway, we had some discussions that were quite interesting.  It was a very good group.

Feedback


From: Andrew James Carter 
Date: Thu, Jun 7, 2012 at 8:41 AM
Subject: Re: 2 quick feedback items

Hi Chris,

Two things arising from the [Stavanger] DISC that I can quickly send some feedback on:

1.   Transforming from Thomsen parameters to stiffnesses and back again.

I’m sure that by now someone else has already remarked on this, but in both your Backus Number article and the DISC book you don’t mention that whilst going from stiffnesses to Thomsen parameters is unique, going in the other direction is non-unique. Because of the quadratic relation between delta and the stiffness components it is necessary to choose the sign of (c13 + c55) (Voigt notation) in going from Thomsen’s parameters back to stiffnesses. This is dealt with in Tsvankin’s 2001 book on page 19. I think it’s a good idea to mention this when providing equations to go from Thomsen’s parameters to stiffnesses in case the unlikely event happens that one day someone stumbles upon a geological material of importance that violates this assumption.

2.  Definitions of Q. 

I agree with you in general about avoiding unnecessary approximations that can lead to hidden errors, although a high-Q approximation simplifies matters if you choose to use a different definition of Q than the one you and Kjartansson use! A particularly good reference on definitions of Q is O’Connell and Budiansky (1978). This paper explains the relation between the definition of Q that Kjartansson uses and Futterman’s choice of definition. I prefer Kjartansson’s choice as it is better behaved for strong attenuation and has a simpler relation to the complex modulus in the wave equation, and it allows the development of Kjartannson’s elegant CQ model. The point is though, as long as you are working in a high-Q approximation the difference between the two definitions is not especially significant, but once you choose to write everything out exactly, it is necessary to remember that you are using a different definition of Q than, for example, Aki and Richards. Aki and Richards used what I refer to as the “2pi definition” as opposed to the “4pi definition”, as did Futterman. I’m afraid I haven’t had time to check through the start of your attenuation chapter yet, but I will try to do so for my own satisfaction if I get time. I couldn’t see anything wrong after a quick look through though. I do think it might be useful for your readers to be aware that different attenuation laws e.g. Kolksy-Futterman and Kjartansson use different definitions of Q, and that these differences begin to matter at Q values that could actually be encountered locally within seismic sections containing highly attenuative zones.

Some evidence regarding 1d-scattering attenuation/stratigraphic attenuation that conflicts with some of your argument to follow when I get a bit more time.

Best regards,

Andrew



About town

Even in late May, Stavanger is a cold and windy place, although they tell me I saw it on a very balmy day.  Still, it was windy, damp and cold.  The Norwegians have a saying: "There is no such thing as bad weather, only bad clothes."

The big boats come in very close with Stavanger's deep water harbor.

This town is proud of it's role in oil and gas.  No such thing in Houston.

Sam and interesting wall art.

No idea, but someone thought she might be getting married.

DISC 13 Aberdeen (29 May)

The Aberdeen DISC was held at the Copthorne Hotel with 24 attending. There were some hiccups at the beginning about a projection screen that was too small for the job and slide images being cropped top and bottom.  But we soon had a big screen and fixed the cropping problem.  From there it was clear sailing.  

About town and country

The short hop from London to Aberdeen was little more than an hour, but it took us from the bustle of a city in full-tourist season getting ready for the Queen's Jubilee and the Olympics to a quiet Scottish town.  It is a gray place: The name 'Granite City' is well-dserved, I never saw a house made of wood.  The big plan here was a pilgramige to St. Andrews, the birthplace of golf.   

On Sunday we rented a diesel VW Golf that got about 50 MPG (why don't we have these in the states?), and wisely opted for the navigation system.  My daughter Sam was still visiting from Ontario, so she served as navigator.  I have driven on the right side of the rode a few times, so it came back pretty quickly.  But, according to Sam, I did seem to have an alarming tendency to crowd the left-side of the road and get halfway through a roundabout and accelerate to the exit road.

We took a reconnaissance trip Sunday afternoon down the coast road toward Dundee.  We stopped at two grand castles, Dunnotar and Edzell.  Back in Aberdeen that night we attended Legally Blonde The Musical, which was an absolute joy.  See it if you can.

On Monday, we headed for St. Andrews with Jill Abbott (my SEG handler) along for the ride.  She agrees with Sam about my slingshot driving through roundabouts.  Surely the Old Course at St. Andrews could not live up to 30 years of expectation, but somehow it did.  Knowing all the stories of Old Tom Morris and his son Young Tom, Nicklaus, Watson, and the failed dreams of a thousand more.

One order of business was finding a hat.  My best Scottish hat was lost at the summit of Mt. Evans outside Denver in a 70 MPH gale last summer.  I was up there with Sam who was working at LASP in Boulder, a group she returns to this summer to pursue a PhD in Aeronautical Engineering.  Anyway, we found the hat.  Cashmere, made in Scotland and bought on a street walked by Old Tom.  As it should be.

One rushed afternoon in St. Andrews is not enough.  I shall return.

Sam and the long walk to Dunnotar Castle

Edzell castle

Comfy, our mascot, and the musical program.

The Old Course at St. Andrews and the R&A Golf Club

The new hat