杏吧原创

EARTHQUAKES may prove impossible to predict, but their aftershocks may be an
easier nut to crack. Geophysicists think they will be able to produce maps of
probable aftershock locations just hours or days after the initial quake,
allowing residents to avoid their effects.

Aftershocks depend on a number of factors, including the geometry of fault
lines and planes across which rock is slipping, the amount of slippage at
different spots along the fault, and the amount of fluid movement inside the
rocks. Gathering all that data after a quake can take time.

But by studying a 7.4 magnitude earthquake that occurred in 1992 in Landers,
California, researchers say you can make a good guess about aftershocks based on
just some of the data. 鈥淵ou don鈥檛 need to know the distribution of slip in
detail, as long as you know the geometry,鈥� says Sandy Steacy of the University
of Ulster in Northern Ireland. 鈥淭hat鈥檚 really, really encouraging.鈥�

In June, as part of a three-year project led by John McCloskey, Steacy and
her Ulster colleagues began studying the geometry of fault planes and the
effective stress they place on other portions of the fault. They鈥檒l be analysing
data from over a dozen major Californian quakes and six European quakes.

鈥淭he point is to see if it鈥檚 feasible,鈥� says Steacy. Their preliminary work
suggests it will be possible to alert emergency response crews to danger spots,
helping to reduce damage. 鈥淧redicting aftershocks is a much more reasonable
project鈥攜ou have a much better chance of success,鈥� says John Cassidy of
the Geological Survey of Canada. 鈥淚n fact, you have a pretty good chance of
蝉耻肠肠别蝉蝉.鈥�