Summary: 772 Seismological Research Letters Volume 80, Number 5 September/October 2009 doi: 10.1785/gssrl.80.5.772
Earthquake early warning (EEW) systems have historically
been based on traditional seismic instrumentation to provide
rapid location of the earthquake source and its magnitude.
Instrumentation includes broadband velocity and strong
motion acceleration sensors, which measure dynamic ground
motions with great accuracy (e.g.
seismic early warning of events requires continuous monitor-
ing of a suite of stations looking for changes in key parameters.
Most algorithms use displacement when trying to estimate
the potential magnitude of an event from the initial few sec-
onds. e magnitude estimates are made on the ratio of the
short-term average displacement to the long-term average and
on the apparent frequency of the initial energy. With seismic
data, displacement has to be obtained by an integration of the
broadband sensors or a double integration of the strong motion
sensors. Due to the bandwidth and the dynamic range lim-
its of seismometers, the accuracy of displacements so derived