HR: 16:00h
AN: S24B-01 [Abstracts]
TI: Determination of earthquake early warning parameters, τc and Pd
AU: * Wu, Y
EM: drymwu@ntu.edu.tw
AF: National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
AU: Kanamori, H
EM: hiroo@gps.caltech.edu
AF: California Institute of Technology, MC 100-25
Caltech, Pasadena, CA 91125, United States
AB:
We explore a practical approach to earthquake early warning in southern California, Taiwan, and Japan by
determining a ground-motion period parameter τc and a high-pass filtered displacement amplitude
parameter Pd from the initial 3 sec of the P waveforms. At a given site, we estimate the magnitude of an event
from τc and the peak ground-motion velocity (PGV) from Pd. The incoming 3-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 cutoff 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 relationships
between τc and magnitude (M) for southern California, Taiwan, and Japan, and between Pd and PGV
for both southern California and Taiwan. Those 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 multi-station 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 sec of the origin time of a large
earthquake whose subsequent ground motion may last for tens of seconds.
DE: 7200 SEISMOLOGY
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7215 Earthquake source observations (1240)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting