
The unusually rich detail comes from an extensive network of sensors that were placed at sites across Japan after that country's Kobe earthquake of 1995, a magnitude 6.8 quake that killed more than 6,000 people because its epicenter was near a major city.
"The Japanese have the best seismic information in the world," said Lucy Jones, chief scientist for the Multi-Hazards project at the U.S. Geological Survey, at a Saturday news conference at Caltech in Pasadena. "This is overwhelmingly the best-recorded great earthquake ever."