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Magnitude estimation using the first three seconds P‐wave amplitude in earthquake early warning
Author(s) -
Wu YihMin,
Zhao Li
Publication year - 2006
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 - 10.1029/2006gl026871
Subject(s) - magnitude (astronomy) , seismology , epicenter , amplitude , geology , geodesy , earthquake magnitude , attenuation , p wave , standard deviation , arrival time , displacement (psychology) , physics , statistics , mathematics , optics , geometry , scaling , engineering , astronomy , transport engineering , cardiology , psychotherapist , atrial fibrillation , medicine , psychology
Pd is the peak amplitude of displacement in the first three seconds after the arrival of the P wave. We investigated the attenuation of Pd with the hypocentral distance R in southern California as a function of magnitude M , and obtained the following relationship: log ( P d ) = −3.463 + 0.729 × M − 1.374 × log ( R ) ± 0.305. Given an earthquake location determined by the P ‐wave arrival times at stations close to the epicenter, this relationship can be used to define a so‐called “ Pd magnitude” of earthquakes. Our result shows that for earthquakes in southern California the Pd magnitudes agree with the catalog magnitudes with a standard deviation of 0.18 for events less than magnitude 6.5. Therefore, Pd is a robust measurement for estimating the magnitudes of earthquakes and has practical application in earthquake early warning systems.