Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases?
Bulletin of the Seismological Society of America
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Abstract
We investigate whether a shallow-dipping thrust fault is prone to waveslip interactions via surface-reflected waves affecting the dynamic slip. If so, can these interactions create faults that are opaque to radiated energy? Furthermore, in this case of a shallow-dipping thrust fault, can incorrectly assuming a transparent fault while using dislocation theory lead to underestimates of seismic moment? Slip time histories are generated in three-dimensional dynamic rupture simulations while allowing for varying degrees of wave-slip interaction controlled by fault-friction models. Based on the slip time histories, P and SH seismograms are calculated for stations at teleseismic distances. The overburdening pressure caused by gravity eliminates mode I opening except at the tip of the fault near the surface; hence, mode I opening has no effect on the teleseismic signal. Normalizing by a Haskell-like traditional kinematic rupture, we find teleseismic peak-to-peak displacement amplitudes are approximately 1.0 for both P and SH waves, except for the unrealistic case of zero sliding friction. Zero sliding friction has peak-to-peak amplitudes of 1.6 for P and 2.0 for SH waves; the fault slip oscillates about its equilibrium value, resulting in a large nonzero (0.08 Hz) spectral peak not seen in other ruptures. These results indicate wave-slip interactions associated with surface-reflected phases in real earthquakes should have little to no effect on teleseismic motions. Thus, Haskell-like kinematic dislocation theory (transparent fault conditions) can be safety used to simulate teleseismic waveforms in the Earth.
Suggested Citation
Smith, D., Aagaard, B.T., Heaton, T.H., 2005, Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases?: Bulletin of the Seismological Society of America, v. 95, no. 3, p. 800-817, https://doi.org/10.1785/0120030171.
ISSN: 1943-3573 (online)
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases? |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120030171 |
| Volume | 95 |
| Issue | 3 |
| Year Published | 2005 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Bulletin of the Seismological Society of America |
| First page | 800 |
| Last page | 817 |