Inside
Science News Service: The largest earthquake on record was
the magnitude-9.5 Chile earthquake of 1960. It accounts for
about a quarter of the total seismic strain released worldwide
since 1990. The magnitude-9.0 quake in Japan on 1 March
released one twentieth of the global total. Richard Aster, of
the New Mexico institute of Mining and Technology, says that we
may be in the middle of a period of large earthquakes after a
lull in the 1980s and 1990s. Global seismic data show periods
of relative quiet, with fewer large earthquakes, as well as
spikes of activity. The records only go back to the beginning
of the 20th century, so there is uncertainty about what, if
anything, the clusters of large quakes might mean. Andrew
Michael, a geophysicist at the US Geological Survey in Menlo
Park, California, has concluded that the overall pattern of
large earthquake occurrences is random, once aftershocks are
removed from the data.
