The attenuation of Fourier amplitudes for rock sites in eastern North America
Bulletin of the Seismological Society of America
By: Gail M. Atkinson and David M. Boore
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Abstract
We develop an empirical model of the decay of Fourier amplitudes for earthquakes of M 3–6 recorded on rock sites in eastern North America and discuss its implications for source parameters. Attenuation at distances from 10 to 500 km may be adequately described using a bilinear model with a geometric spreading of 1/R1.3 to a transition distance of 50 km, with a geometric spreading of 1/R0.5 at greater distances. For low frequencies and distances less than 50 km, the effective geometric spreading given by the model is perturbed using a frequency‐ and hypocentral depth‐dependent factor defined in such a way as to increase amplitudes at lower frequencies near the epicenter but leave the 1 km source amplitudes unchanged. The associated anelastic attenuation is determined for each event, with an average value being given by a regional quality factor of Q=525f 0.45. This model provides a match, on average, between the known seismic moment of events and the inferred low‐frequency spectral amplitudes at R=1 km (obtained by correcting for the attenuation model). The inferred Brune stress parameters from the high‐frequency source terms are about 600 bars (60 MPa), on average, for events of M>4.5.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | The attenuation of Fourier amplitudes for rock sites in eastern North America |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120130136 |
| Volume | 104 |
| Issue | 1 |
| Year Published | 2014 |
| Language | English |
| Publisher | Seismological Society of America |
| Contributing office(s) | Earthquake Science Center |
| Description | 16 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Bulletin of the Seismological Society of America |
| First page | 513 |
| Last page | 528 |
| Country | Canada;United States |
| Google Analytic Metrics | Metrics page |