Summary: Application of real time GPS to earthquake early warning
Richard M. Allen1
and Alon Ziv2
Received 28 April 2011; revised 1 July 2011; accepted 6 July 2011; published 24 August 2011.
 We explore the use of real time high rate GPS dis-
placement data for earthquake early warning using 1 Hz
displacement waveforms from the April 4, 2010, Mw 7.2
El Mayor Cucapah earthquake. We compare these data to
those provided by the broadband velocity and accelerometer
instrumentation of the Southern California Seismic Network.
The unique information provided by the GPS based dis-
placement timeseries is the permanent/static displacement.
Using a simple algorithm that can be applied in real time, we
extract the static offset shortly after the S wave arrival,
around the time of the observed peak shaking at the same site,
and before shaking at more distant locations. These data can
be used, as they become available, to provide a robust esti-
mate of the earthquake magnitude, which ranges from 6.8 to
7.0 in this case. We therefore conclude that real time high
rate GPS can provide a useful and independent assessment of