By Erin Wayman
A hidden hot spot deep within the Earth could have set off seismic activity causing some earthquakes in the eastern United States.
Researchers have discovered a track of hot rock at the base of the North American plate, stretching from Missouri to Virginia. It marks a trail, they say, where the westward-drifting continent passed over a hot spot tens of millions of years ago. A hot spot is the top of a plume of abnormally hot, buoyant rock in the mantle that wells up like a blob in a lava lamp.
Hot spots can fuel volcanoes, and scientists think a hot spot in the Pacific Ocean created the Hawaiian Islands (SN: 10/22/11, p. 8). Under much thicker continental rock, mantle plumes may heat up but rarely leave a mark on the surface, Risheng Chu of the Chinese Academy of Sciences and colleagues argue September 15 in Nature Geoscience.
The hot spot’s heat, however, might have stretched and pulled the North American plate, causing the brittle crust to crack and initiating seismic activity in the eastern U.S. “If a hot spot indeed exists, it’s plausible that the structure could trigger seismic activity,” says Matthew Fouch, a seismologist at the Carnegie Institution for Science in Washington, D.C. For instance, the hot spot might have activated the New Madrid zone, which is famous for unleashing a series of powerful quakes in 1811 and 1812 that rattled the Midwest (SN: 12/3/11, p. 22).