ISSN:
1420-9136
Keywords:
Source spectra
;
Scaling law
;
Barrier model
;
Strong ground motion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract A set of acceleration source spectra is constructed using the observed parameters of the specific barrier model of Papageorgiou and Aki. The spectra show a significant departure from the ‘ω2-model’ at the high frequency range. Specifically, the high frequency spectral amplitudes of seismic excitation are higher as compared to the level predicted by the ‘ω2-model’. This is also supported by other observational evidence. The high frequency amplitudes of acceleration scale proportionally to the square root of the rupture areaS, to the rupture spreading velocityv, and to the local strain drop (Δσ/μ) (=strain drop in between barriers). The local strain drop in between barriers is not related in a simple way to the global strain drop, which is the strain drop estimated by assuming that it is uniform over the entire rupture area. Consequently, the similarity law does not apply. Using the source spectra which we constructed, we derive expressions for high frequency amplitudes of acceleration such asa rms anda max. Close to the fault both are independent of fault dimensions and scale as (Δσ/µ)(Δf)1/2, while away from the fault plane they scale asW 1/2(Δσ/µ)(Δf)1/2, whereW is the width of the fault and Δf is the effective bandwidth of the spectra.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00880736
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