The tsunami that hit Southeast Asia started with an earthquake along a known plate line in the Indian Ocean. Earthquakes are often motion of plates from side to side, but this earthquake was vertical.
The plates separated suddenly, just west of Sumatra. Water rose very rapidly and slide down both sides toward shore. It gained momentum as it traveled, and when it hit shore, the bottom dragged against the ocean floor and the top came over onto the beach. That was the wall of water witnesses describe.
Could it happen on the Great Lakes? MSU geology professor Thomas Vogel says no. Michigan sits on just one tectonic plate. There are ancient plates, but they haven't been active for about a billion years. Any seismic activity Michigan has had in the past has been vibrations and shifts in this single plate, motion that Vogel says is rarely noticeable.
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