Determination of earthquake early warning parameters, τc and Pd, for southern California
Resource
Geophysical Journal International 170 (2): 711-717
Journal
Geophysical Journal International
Journal Volume
170
Journal Issue
2
Pages
711-717
Date Issued
2007
Date
2007
Author(s)
Abstract
We explore a practical approach to earthquake early warning in southern California by determining a ground-motion period parameter τc 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 τc 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, τc and Pd are computed. We found the relationship between τc 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. In an ideal situation, such warnings would be available within 10 s of the origin time of a large earthquake whose subsequent ground motion may last for tens of seconds. © 2007 The Authors Journal compilation © 2007 RAS.
Subjects
Earthquake early warning; Magnitude; P-waves; Seismic hazard mitigation
Type
journal article
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