Earthquake early warning system for southern California
Presenter: Chiao Chu Hsu                            Advisor: Kuo Liang Wen
Abstract

We explore a practical approach to earthquake early warning in southern California by determining a ground-motion period parameter  and a high-pass filtered displacement amplitude parameter Pd from the initial 3 s of the P waveforms recorded at the Southern California Seismic Network stations for earthquakes with M >4.0. At a given site, we estimate the magnitude of an event from and the peak ground-motion velocity (PGV) from Pd. The incoming three component signals are recursively converted to ground acceleration, velocity and displacement. The displacements are recursively filtered with a one-way Butterworth high-pass filter with a cut-off frequency of 0.075 Hz, and a P-wave trigger is constantly monitored. When a trigger occurs, and Pd are computed.We found the relationship between and magnitude (M) for southern California, and between Pd and PGV for both southern California and Taiwan. These two relationships can be used to detect the occurrence of a major earthquake and provide onsite warning in the area around the station where onset of strong ground motion is expected within seconds after the arrival of the P wave. When the station density is high, the methods can be applied to multistation data to increase the robustness of onsite early warning and to add the regional warning approach.

Keywords: earthquake early warning, magnitude, P-waves

References:

Wu, Y.M. and Zhao, L.(2006), Magnitude estimation using the first three seconds P-wave amplitude in earthquake early warning, Geophys. Res.Lett., 33, L16312

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Wu, Y.M. , Kanamori, H.,Allen, R.M. and Hauksson, E.(2007), Determination of earthquake early warning parametersand Pd for southern California, Geophys. J. Int,pp711-717

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