Open AccessTwo‐dimensional coda Q structure beneath Tohoku, NE Japan
Author(s) -
Matsumoto Satoshi,
Hasegawa Akira
Publication year - 1989
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1989.tb02018.x
Subject(s) - coda , seismology , geology , amplitude , weighting , s wave , seismic wave , geodesy , physics , optics , acoustics
SUMMARY Based on the single scattering model, coda‐ Q values ( Q c ) are estimated for several frequency bands from the time decay of coda wave amplitude. The Q c value shows a regional variation and frequency dependency of the form Q c α f n , where n is found to be 0.6–1.2. A method for estimating the 2–D Q c structure has been developed to investigate the regional variation of the Q c value beneath Tohoku, the NE part of Honshu, Japan. The Q c value at each grid point spatially distributed is estimated by averaging the observed Q c values for many event‐station pairs with adequate weighting factors. The weighting factor at each grid point for an event‐station pair is calculated by taking into account the amount of energy contribution to the coda wave from that grid point. The obtained 2‐D Q c structure shows some relation to the S ‐wave velocity structure, the Q s structure and the seismic activity in this area. In general, low Q c regions have a tendency to correspond to the regions with low S ‐wave velocity, low Q s value and high seismic activity, while high Q c regions correspond to those with high S ‐wave velocity, high Q s value and low seismic activity. In the regions around active volcanoes and near the coast of the Japan Sea the Q c value is relatively low, whereas it is relatively high near the coast of the Pacific Ocean.