Ireland and Britain should be, seismologically speaking, equally boring. The two islands lie thousands of kilometers from the nearest plate boundary and are not volcanic hot spots. But though the ground rarely rumbles in Ireland, neighboring Britain experiences plenty of weak and moderate earthquakes.
The lithosphere—Earth’s outermost rocky veneer, which includes the crust and the solid upper mantle—is thicker and cooler beneath Ireland than it is beneath Britain, new research has suggested. Cool, thick lithosphere is mechanically stronger than warm, thin lithosphere, which could explain the Emerald Isle’s puzzling paucity of earthquakes. The new results, published in Geophysical Journal International, hinted that lithosphere thickness could underpin patterns in seismic activity in other places far from plate boundaries.
Around 90% of all earthquakes—including nearly all the most destructive ones—start at the boundaries between tectonic plates. Plate or continental interiors tend to be seismically quiet, though they’re not dead. The New Madrid ...
