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Analysis of seafloor seismograms of the 2003 Tokachi‐Oki earthquake sequence for earthquake early warning
Author(s) -
McGuire Jeffrey J.,
Simons Frederik J.,
Collins John A.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl033986
Subject(s) - seismology , geology , aftershock , seismogram , magnitude (astronomy) , waveform , tsunami earthquake , submarine pipeline , peak ground acceleration , wavelet , seafloor spreading , warning system , amplitude , foreshock , arrival time , geodesy , geophysics , ground motion , computer science , geotechnical engineering , physics , quantum mechanics , astronomy , artificial intelligence , transport engineering , engineering , telecommunications , radar
Earthquake Early Warning (EEW) algorithms estimate the magnitude of an underway rupture from the first few seconds of the P ‐wave to allow hazard assessment and mitigation before the S ‐wave arrival. Many large subduction‐zone earthquakes initiate 50–150 km offshore, potentially allowing seafloor instruments sufficient time to identify large ruptures before the S ‐waves reach land. We tested an EEW algorithm using accelerograms recorded offshore Hokkaido in the region of the 2003 M w 8.1 Tokachi‐Oki earthquake and its aftershocks. A wavelet transform of the first ∼4 s of the P ‐wave concentrates information about earthquake magnitude from both waveform amplitude and frequency content. We find that wavelets with support of a few seconds provide discriminants for EEW that are both accurate enough to be useful and superior to peak acceleration or peak velocity. Additionally, we observe a scaling of wavelet coefficient magnitude above M w 6.0 indicating that, at least for the mainshock (M w 8.1) and largest aftershock (M w 7.1), the final size of a rupture could have been estimated from the initial portion of the seismogram.