New analyses of ground motions caused by large earthquakes suggest that it may be possible to estimate the full magnitude of such quakes immediately after they start rumbling. That could enable emergency systems to better warn distant populations of a temblor before it reaches them.
Currently, it isn't possible to measure an earthquake's total magnitude until the rumbling has stopped. That's because the seismic energy that's released depends on the total slippage that occurs between two sides of a fault, says Richard M. Allen, a seismologist at the University of California, Berkeley.
He and his colleagues have discovered a