The determination of Q0 and η (where Q = Q0fη) from seismic coda over the United States by Singh and Herrmann (1983) has been extended to cover a large area of southeastern Canada (south of 50°N, east of 80°W). The model used assumes, like that of Singh and Herrmann (1983), that the coda is generated by isotropic single scattering of surface waves, but also takes into account nonzero source-receiver distances. An average value of 0.43 is found for η for the whole region. Assuming this value of η, and using data in the 1 to 10 Hz range, Q0 has been estimated independently in nine different subregions, so that the variation of Q0 within the area of study can be seen. Q0 varies from 480 in New Brunswick to 770 near Ottawa. Q0 is also high (760) in the Adirondack Mountains and near Val-d'Or, Quebec (730), but lower along the St. Lawrence River (620). The results agree well with those of other studies in which Q for the same geographical regions is determined by other methods.
Above 10 Hz and below 1 Hz, Q is more strongly dependent on frequency than in the 1 to 10 Hz range. The same result has been obtained by Shin and Herrmann (1987) by a different method.