A SUDDEN SEISMIC SHIFT

A few years ago I happened to read Bill Bryson’s rather excellent book about general science called “A short history of nearly everything”. It was a book that managed to both fascinate me and terrify me at the very same time, because, despite being a lovingly crafted and uplifting tribute to all that is wonderful about modern scientific discovery, every so often you would turn the page and find yet another potential M.E.E. (Mass Extinction Event) for the human race. From the possibility of huge meteors slamming through the atmosphere at less than a minute’s notice, to the huge supervolcano lurking under Yellowstone, it was all there, in most cases quite a few years before “Horizon” got around to sharing their weekly “How we’re all doomed this time” documentaries. The book goes to an awful lot of trouble to reassure the reader that we’re probably going to be fine, of course, but when you read what he happens to mention about Tokyo (on page 265 in my copy), you do start to wonder.

One of the things that came out of reading the book is that I now have a link on my computer to a website that monitors seismic activity across the globe called the IRIS Seismic monitor (http://www.iris.edu/seismon/). For quite a few months after reading the book, I would check it daily and share the latest wisdom I gleaned from it with anybody unlucky enough to be in earshot and no doubt bore them rigid with what I had seen there. As is the way with many of these things, the years drifted by and I kind of forgot the link was there, until someone mentioned the very same maps it depicts in a thread I was reading through in the aftermath of the Japanese earthquake on Friday. They described it as being “lit up like a Christmas tree” and when I had a quick peek, it turns out that they were not wrong. What we need to realise is, of course, that if all this movement is happening on one side of the Pacific plate, as sure as eggs-is-eggs, the other side is going to start shifting soon, and the long expected “big one” along the west coast of North America might be more imminent than we’d like to believe.

IRIS Seismic Monitor 11/03/2011

The Earth’s crust is made up of about twenty large plates that move around on the surface of a molten ball of rock. Because it is hot, that molten rock moves around in convection currents in much the same way as you can see when you put a drop of milk into your coffee and don’t stir it. Interestingly enough, if you leave that same coffee to cool down and a skin forms on the top (this seemed to happen a lot when I was younger, but less so now, probably due to the milk being semi-skimmed… but I digress) that’s pretty much how the relatively thin surface of the planet we happen to live on was formed. Obviously (and luckily for the human race) this all occurs at a much, much slower speed, but unluckily it has not formed one lovely smooth coating like the chocolate coating on a Malteser, but a set of plates that are constantly butting up against each other at the edges and shuffling around trying to get comfortable.

Where the edges do meet, and one unstoppable force meets another, we get tension and friction as one or other of the plate edges gets the upper hand and the other one has to go somewhere and ultimately something’s got to give and we call that something Earthquakes. The power and energy behind this movement dwarves anything the human race can achieve. Our underground nuclear tests probably don’t help much with keeping things stable, but they are like pin pricks compared to the power of the planet. At the same time one plate can be lifting to form mountain ranges and the other plate can be being pushed under it to be reconsumed by the molten rock below. So, if all this rock is being consumed and lost, how come we’ve still got a globe made up of a relatively solid surface? Why aren’t there gaps? Well of course there are. The rifts where the continental plates pull apart is where the hot molten rock from within the planet escapes to fill the gaps, creating brand new crust in the volcanic regions.

Plate tectonics is a fascinating subject and in its own simple way, thoroughly explains an awful lot about the Earth and how it works. I was taught it at school and was of the general opinion that we - the human race, that is - had always believed this theory, and the whole concept of “continental drift” which seems so familiar and obvious to us now, and so it came as something of a surprise that it was only widely accepted as a valid scientific idea as recently as 1964. Just forty seven years ago. Less than a lifetime. I have a “How and Why Wonder Book” about the Earth from slightly after that time that almost completely fails to mention it, and a radio play I recently heard on CD from about that time seemed to have very little insight into it either. Before that, it seems, we thought these things were more random than that, and that certain parts of the world were just more prone to it. Now of course we know better, but that doesn’t make it any easier to live with.

Apparently, as I’m sitting here, my desk is moving towards America at “roughly the same speed as my fingernails grow at” as Bill Bryson put it. If I waited long enough, I could save a small fortune on any air fares across the Atlantic, it would seem, although apparently, if the projections are correct, one day what was once known as the Atlantic Ocean will be larger than the what used to be known as the Pacific Ocean.

As human beings we do like to think that we’ve made our mark on things, but we really do struggle with geological timescales. In pretty much the whole history of mankind, most of our landscape, barring the odd earthquake and volcano, has seemed to be fairly constant. “Steady as a rock” is one of those clichés that’s rapidly turning out to be less true than we thought. We now know an awful lot now about plate tectonics and continental drift and how the world is constantly changing, but we can still stand on the same plateaus that the ancient Egyptians stood up on and still see pretty much the same landscape that they did.

For all of human history our world and our maps to move around within it have appeared to be much the same, and we believed for a long time that nothing much changes and nothing much ever would. You can see computer animations of the whole history of continental drift on the surface of the Earth that last just a few seconds, and the world that you and I recognise and live on is only visible for less than the blink of an eye, and yet all of our history has been played out on a seemingly unshifting world. So it is only human arrogance that makes us think that we matter, and the notion that our legacy and our buildings will last ‘forever’ is really quite absurd. What do we really know of the day-to-day world of one million years ago? What will the world of a million years from now know of ours? In the blink of a geological eye we could be all be gone and totally forgotten, unseen, unknown and uncared for by a cold, unforgiving universe, and with all our understanding and knowledge gone with us.