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Determination of earthquake early warning parameters, τ_c and P_d, for southern California

Wu, Yih-Min and Kanamori­, Hiroo and Allen, Richard M. and Hauksson, Egill (2007) Determination of earthquake early warning parameters, τ_c and P_d, for southern California. Geophysical Journal International, 170 (2). pp. 711-717. ISSN 0956-540X. doi:10.1111/j.1365-246X.2007.03430.x.

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We explore a practical approach to earthquake early warning in southern California by determining a ground-motion period parameter τ_c 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 τ_c 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.

Item Type:Article
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URLURL TypeDescription
Kanamori­, Hiroo0000-0001-8219-9428
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2007 The Authors. Journal compilation © 2007 The Royal Astronomical Society. Accepted 2007 February 28. Received 2007 February 28; in original form 2006 August 10. The first author wishes to thank Dr. Li Zhao and David M. Tratt for providing many thought-provoking comments. We thank the SCSN and the Southern California Earthquake Data Center for providing public access to the seismological data, and the staff at the Seismological Laboratory at Caltech and U. S. Geological Survey at Pasadena. This research was supported by the National Science Council of the Republic of China (NSC95-2119-M-002-043-MY3 & NSC94-2116-M-002-021), and Caltech’s Tectonics Observatory. Contribution number 9119, Division of Geological and Planetary Sciences, California Institute of Technology (Caltech), Pasadena.
Group:Seismological Laboratory, Caltech Tectonics Observatory
Funding AgencyGrant Number
National Science Council (Tapei)NSC95-2119-M-002-043-MY3
National Science Council (Tapei)NSC94-2116-M-002-021
Caltech Tectonics ObservatoryUNSPECIFIED
Subject Keywords:earthquake early warning, magnitude, P-waves, seismic hazard mitigation
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences9119
Issue or Number:2
Record Number:CaltechAUTHORS:20130430-113958269
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38182
Deposited On:01 May 2013 20:40
Last Modified:09 Nov 2021 23:35

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