Sergei Lebedev, a seismologist at the University of Cambridge and lead author of the new study, described the situation by quoting British Geological Survey seismologist Roger M. That’s the case in the British Isles, where the dramatic seismic contrast between Britain and Ireland is a centuries-old mystery. And it’s often unclear why some places deep within continents have more earthquakes than others. The rarity of intraplate earthquakes has made it harder for scientists to understand them. “The question is, What’s controlling seismicity in continental interiors away from plate margins?” “We have a very good frame of understanding seismicity at plate margins,” said geologist Mike Sandiford of the University of Melbourne, who wasn’t involved in the new study. Get the most fascinating science news stories of the week in your inbox every Friday. The New Madrid Seismic Zone in the Mississippi River Valley, for instance, released a series of magnitude 7.3–7.5 earthquakes in late 1811 and early 1812, despite sitting in the middle of the North American plate. Plate or continental interiors tend to be seismically quiet, though they’re not dead. Ireland’s Missing EarthquakesĪround 90% of all earthquakes-including nearly all the most destructive ones-start at the boundaries between tectonic plates. 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. Cool, thick lithosphere is mechanically stronger than warm, thin lithosphere, which could explain the Emerald Isle’s puzzling paucity of 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. But though the ground rarely rumbles in Ireland, neighboring Britain experiences plenty of weak and moderate earthquakes. ![]() The two islands lie thousands of kilometers from the nearest plate boundary and are not volcanic hot spots. ![]() Ireland and Britain should be, seismologically speaking, equally boring.
0 Comments
Leave a Reply. |