Global Warming May Trigger Greater Seismic Activity

The melting of glaciers driven by global warming portends a seismically turbulent future. When glaciers melt, the massive weight on the Earth's crust is reduced, and the crust “bounces” back in what scientists call an "isostatic rebound.” This process can reactivate faults, increase seismic activity, and lift pressure on magma chambers that feed volcanoes.

This has happened several times throughout Earth's history, and the evidence suggests that it is starting to happen again. Of course, not every volcanic eruption and earthquake in the years to come will have a climate-change link.

There are implications for all parts of the world where glaciers and active faults coincide, including the Alps, Himalayas, Rocky Mountains, Andes and the Southern Alps in New Zealand. But of particular concern is the continental shelf around Greenland, where a massive melting of the ice sheet might trigger earthquakes strong enough to trigger underwater landslides which in turn could generate tsunamis.

Melting ice and sea-level rise also mean that previously exposed continental margins become inundated with water. At the end of the last ice age, the extra load was more than enough to reactivate faults and trigger earthquakes around the rims of all the major ocean basins, some of which are thought to have set off giant landslides on the sea floor.

“A particular worry,” writes Bill McGuire in New Scientist, is that such seafloor landslides could “contribute to large-scale releases of methane gas from the solid gas hydrate deposits that are trapped in marine sediments. Gas hydrates have been identified around the margins of all the ocean basins, and outbursts of gas may occur as sea temperatures climb or as rising sea levels trigger underwater quakes in the vicinity.”

Sharon Begley, “How Melting Glaciers Alter Earth’s Surface, Spur Quakes, Volcanoes,” Wall Street Journal Online, 9 June 2006.
Link: http://online.wsj.com/public/article/SB114981650181275742-sOx58NXvfKz2szefZXutgTSbaDI_20070608.html; and
Bill McGuire, “Climate Change: Tearing the Earth Apart?,” New Scientist, 26 May 2006,
Link: http://www.newscientist.com/channel/earth/mg19025531.300.