GeoCarta Has Moved

Dec 15, 2005

Northeast U.S. Slowly Moving South

A large section of the Northeastern United States is slowly moving southward in relation to the rest of the continent, a team of researchers have discovered. Previous efforts to measure such movements had yielded conflicting results. However, improvements in Global Positioning System (GPS) technology enabled the research team, led by Dr. Eric A. Calais of Purdue University to measure the continent's rigidity with greater accuracy.

The measurements showed that the northeast is moving south at a rate of about a millimeter a year. While that pace isn't likely to warm up winters in the Northeast any time soon, it is significant for two reasons:
  • It calls into question the three decade old view among earth scientists that crustal plates are rigid objects. "Our findings do not disprove this view entirely, but they encourage us to see that deviations to the rule can occur," Dr. Calais said.
  • This movement gives scientists clues about the viscosity of the earth's interior. The movement may even influence seismic activity in places such as Quebec, which though far from plate boundaries has experienced strong earthquakes."
Why is the earth moving? Scientists say that the land is still recovering from being covered by glaciers. The sheer weight of the of the ice actually pressed the earth inward. It has long been known that this part of the continent was moving upward vertically, as the land rebounded from the massive weight. Now it appears that it is moving horizontally as well.

A complete report appears in the current issue of the scientific journal, Nature, or you can read further about the team's investigation here.