A recent conference in London has discussed the links between climate and geological activity, and there’s an excellent report of some of the findings in New Scientist.
I was particularly struck by the fact that there appears to be a link between El Nino and seismic activity, according to Simon Day of the University of Oxford, and Bill McGuire and Serge Guillas of University College London. This is not a matter of future speculation – this is clear and present evidence – of danger.
Since 1973, the arrival of El Niño every few years has correlated with a greater frequency of underwater quakes between magnitude 4 and 6. The team is confident that the two are linked. El Niño raises the local sea level by a few tens of centimetres, and they believe the extra water weight may increase the pressure of fluids in the pores of the rock beneath the seabed. This might be enough to counteract the frictional force that holds the slabs of rock in place, making it easier for faults to slip. “The changes in sea level are tiny,” says Day. “A small additional perturbation can have a substantial effect.”
Changes in rainfall can trigger volcanic eruptions, as in the Caribbean island of Montserrat, where heavy rainfall in 2001 preceded an eruption of the Soufrière Hills volcano. Bear in mind, there is widespread agreement that climate change will increase the number of extreme weather events. (In fact, you can see that it probably is already, by scrutinising this 2006 graph produced by those noted whacky environmentalists at Munich Re, one of the world’s largest reinsurance companies.)
Back to the UCL conference, and a very scary revelation indeed, for those who are hoping that carbon capture and storage will rescue us from the problems of coal.
Even as the US’s first large-scale sequestration operation is getting off the ground at the Mountaineer plant in West Virginia, geophysicists are concerned that burying the carbon could trigger earthquakes and tsunamis. In a carbon sequestration power plant (CCS), CO2 is extracted from the exhaust then pumped into aquifers and old gas fields several kilometres beneath the Earth’s surface. So far so good. But the CO2 expands as it rises through the porous rock, increasing pressure inside. “If enough CO2 is injected into an aquifer, it could increase the pressure enough to reactivate a fault and trigger an earthquake,” warns Andrew Chadwick of the British Geological Survey.
Oh – dear. And again, this is not just wild speculation:
A CCS facility at the Sleipner gas field in the North Sea, may have triggered a magnitude 4 earthquake in 2008. Had it been bigger, says Klose, it might have triggered a tsunami.