BBC Focus Magazine

[The Beige Avenger]

Live coverage:
http://www.telegraph.co.uk/news/worldne ... -live.html

[M Paul Lloyd]

what with the New Zealand quake it makes me wonder if this isn't part of some unpleasant chain reaction?

[Jamie]

It'll be San Andreas next, it's due a biggie.

[Shadowwolf]

what with the New Zealand quake it makes me wonder if this isn't part of some unpleasant chain reaction?

Don't think that they're linked when so far apart but I honestly don't know, Flakkarin might know better. Incidentally there was a small quake in China yesterday though even this lesser powered one caused fatalities.

Dunno whether it was better or worse happening in the afternoon, at least folks were up rather than ambushed whilst sleeping.

[Hyrulian Outlaw]

There was an expert talking on the news earlier and he said that the quake in New Zealand would have little chance of being anything to do with this. As a generalisation there is a 500k boundary from one quake to another running along the fault the quake was on, but he wouldn't rule out there was a very slim chance of them being connected, just extremely unlikely.

[M Paul Lloyd]

Even so if I lived in California I might be considering a holiday out east.

I seem to recall being told that the entire planet rings like a giant bell when these big 8+ magnitude quakes occur.

I'll see if Flakkarin can spare us a little of her expertise?

[Shadowwolf]

Good old Terra apparently shifted some ten centimeters over this.

Reports from the National Institute of Geophysics and Volcanology in Italy estimated the 8.9-magnitude quake shifted the planet on its axis by nearly 4 inches (10 centimeters).

http://edition.cnn.com/2011/WORLD/asiapcf/03/12/japan.earthquake.tsunami.earth/index.html

[Flakkarin]

That was a big one, for sure.

The idea of 'remotely triggered earthquakes' is a relatively new one in the science but it's pretty compelling. Large earthquakes undoubtedly release shock waves across the world, but exactly what triggers individual earthquakes is complex. New Zealand and Japan are both on the Pacific Ring of Fire, both are subject to the subduction of the Pacific Plate, but every point on the huge plate boundary is under it's own stresses. Movement at one point on the plate does not necessarily mean movement at another, but rather the shock waves from a large earthquakes may be enough to tip the balance for a fault zone no matter which plate it's on.
A short, but nice summary: http://www.iris.edu/services/lectures/iris_ssa/ab1_2005.htm

I want to take a moment to be in awe of how well Japan actually came out of this. Many hundreds of people have died, and every death is tragic, but an 8.9 magnitude quake coupled with a tsunami is a tremendous event. If Japan were not so prepared with building design, earthquake drills and warning systems, well, it's harrowing to think of the consequences. My condolences to the dead and injured, by congratulations for the thousands still alive.
Sorry, not scientific I know, unless you think of the science of risk...

[M Paul Lloyd]

Many thanks for that Flakkarin, much appreciated.
The Japanese are a stoic lot aren't they? Well deserving of our support and admiration.

Thought this might help put some of it into perspective.

[Hyrulian Outlaw]

Shadow, that link you posted says the plate slipped some 18 metres

Maybe Flak can explain in simple terms for us non-experts what this actually means? Did it move up, down, across, forwards? What does this mean in relation to the rest of the plate, is there some elasticity involved? If one edge moved 18 meters east for example did the other edge not follow? Where did this movement stop and what effect (besides the obvious quake) is it likely to have. Will it of reduced pressure somewhere else or does all the movement come from the point the plate is formed where magma rises to the suface?

[M Paul Lloyd]

I'll see if Flakkarin can spare us some time... meanwhile as I understand it the mainland of Japan is sitting just west of a point where two deep ocean trenches meet, where the Pacific plate is being forced under the Asian plate so that 18 metres will be mostly sea floor. Rock is elastic but only over very large scales and the reason for the recent quake was because all the energy stored up in the rock was released in one sudden large slip. If it had not got itself stuck and slipped at smaller intervals over a period of time then the effects might have been somewhat less severe.

I have just heard that it may have shifted the Earths axis by as much as 250 millimetres rather than the 100 as previously thought.

[Jamie]

A rather frightening example of the speed in which the tsunami arrived.

http://uk.gizmodo.com/5781566/this-is-t ... sunami-yet

[M Paul Lloyd]

Its the realisation that those vehicles have people in them that sends a shiver down my spine.

[Hyrulian Outlaw]

That video is startling, I alway imagined it would be a huge wave smashing into everthing. It's easy to see from that how people, who probally had never heard the word tsunami before (indonesia perhaps) would have had no idea how quick and how powerful that initial swathe of water would be.

[M Paul Lloyd]

This apparently shows how much the Japanese mainland may have shifted by.

Japan's coastline may have shifted by as much as 4m (13ft) to the east following Friday's 8.9 Magnitude earthquake, according to experts.
Data from the country's Geonet network of around 1,200 GPS monitoring stations suggest a large displacement following the massive quake.
Dr Roger Musson from the British Geological Survey (BGS) told BBC News the movement observed following the quake was "in line with what you get when you have an earthquake this big".
The quake probably shifted Earth on its axis by about 6.5 inches (16.5cm) and caused the planet to rotate somewhat faster, shortening the length of the day by about 1.8 millionths of a second.
Japan's meteorological agency has proposed updating the magnitude of the earthquake to 9.0.
This would make it the joint fifth biggest quake since instrumental records began, but other agencies have not yet followed suit.

Read more
http://www.bbc.co.uk/news/science-environment-12732335

[Flakkarin]

For the dynamics, MPL pretty much said it all!

I did come across a link to a fantastic resource on the event:
http://www.iris.edu/hq/retm

A prof in my department is also giving a talk about the geo of it tomorrow, and I've been commissioned to write a story about the effect on the economy, so more to come!

[Shadowwolf]

The effect to the economy? Should be easy, it will be both a terrible strain and a great boon as I've yet to encounter anything in economics that could not be spun in a multitude of ways

[M Paul Lloyd]

For the dynamics, MPL pretty much said it all!

Really......................! oh......? I was hoping that there was more.

[Hyrulian Outlaw]

Time for a career change MPL, you better watch out Flak, Paul is after your job!

[M Paul Lloyd]

Ha! Lol.....