If you believe in the existence of something called pure science, with no connection to practical use, you weren’t at the Royal Astronomical Society on Friday. There was a paper on the history of the Moon (always a good one, having a prime exhibition space on solar system history three days away from home), one on gravity which I
almost think I understood, and then the
chef d’oeuvre, the Harold Jeffreys Lecture by Bob White
noticed other headband?
of Cambridge University.
Professor White is a great scientist and a terrific public performer. And while the RAS is mainly about, well, astronomy, we also look at the solid Earth. His subject, the way magma (liquid rock) behaves in volcanic places like Iceland, is perfect for great pictures as well as some serious learning. (He pointed out that many of world astronomy’s biggest assets, the Hawaii telescopes, are on top of a volcano larger than Everest. Better check that insurance, everyone.)
His message is partly that when continents get squeezed apart, far more rock ends up as solidified sills (flat intruded bits) than
ever hits the surface to make volcanoes. In addition, and having been trained as a geologist, I was intrigued by just how narrow the dykes (up and down intruded bits) are along which the magma rises. They are only maybe a metre wide on average. He can now track this happening in 3D and in real time in Iceland, through seismometers that detect the tiny earthquakes generated by its progress.
If you get a chance to see White lecture on this stuff, take it. But there was another message he had to offer. This earthquake activity generates new faults inside the Earth. But he has shown that these shallow (say 15km) quakes do not involve massive pressures. Because the rock is lubricated by carbon dioxide gas, the new faults can be generated by pressures not much higher than the air pressure at the Earth’s surface. As he said, this has lessons for the feasibility of carbon capture and storage, which involves sequestering carbon dioxide for geologically long periods of time inside the Earth, and for fracking, which involved deliberately weakening strata inside the Earth to get methane out. Two items of faith of current energy policy slaughtered in a footnote to a talk on volcanoes. Not bad, Professor White.
