Could a tsunami like the one that has just devastated the countries around the Indian Ocean hit the eastern United States?

The answer unfortunately is "yes." There have been in fact several catastrophic Atlantic tsunamis in the last few centuries. Tsunamis (which have nothing to do with tides, despite the frequent term "tidal waves") can be generated by several mechanisms. Sudden movements of the sea floor, accompanying earthquakes, are the most common cause; this is what caused the December 2004 Indian Ocean tsunami (actually several waves, not just one). Volcanic eruptions, such as the Krakatoa event of 1883, can generate powerful tsunamis; the 1883 one killed thousands of people in Indonesia and nearby countries. Submarine landslides could generate tsunamis. In 1929, a tsunami probably produced by such a landslide (triggered by an earthquake) killed several dozen people on the south coast of Newfoundland. A recent study warned that a landslide of the Cumbre Vieja volcano,in the Canary Islands, could produce a damaging tsunami around the North Atlantic. The worst Atlantic tsunami of all was in 1755, produced by the earthquake that destroyed Lisbon, killing some 60,000 people.

Most known tsunamis have been produced at major active subducting plate boundaries, notably those around the Pacific Ocean. However, there are such boundaries in the Caribbean and possibly elsewhere. Added to the danger of submarine landslides, the tsunami danger is a real one for the eastern United States. However, if even a couple of hours warning is given, from seismology, people could move far enough inland ( a few miles) to escape the worst. In areas like Manhattan, moving up to higher floors would help in strong, steel-framed skyscrapers.

This week's question is provided by Dr. Paul Lowman. Paul Lowman is a geophysicist, originally a geologist, in the Geodynamics Branch of the Laboratory for Terrestrial Physics. He joined GSFC in December, 1959, in the Theoretical Division led by Dr. Robert Jastrow. He initially worked on the origin of tektites, argued by Dr. John O'Keefe to come from the Moon. He helped plan the Apollo geophysical experiments, and trained Mercury, Gemini, Apollo, and Skylab astronauts in geologic terrain photography. His most recent work has been compilation of a global tectonic activity map, appearing in his 2002 book "Exploring Space, Exploring Earth." AND he fearlessly (or foolishingly, if you ask him) rides his bike to work along Greenbelt Road (a very high trafficked road) every day!! WOW!