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Broadband frequency-dependent amplification of seismic waves across Bucharest, Romania

Sudhaus, Henriette ; Ritter, Joachim

In: Journal of Seismology, 2009, vol. 13, no. 4, p. 479-497

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    Title
    • Broadband frequency-dependent amplification of seismic waves across Bucharest, Romania
    Author
    • Sudhaus, Henriette. Institute of Geophysics, ETH Zurich, Sonneggstr.5, 8092, Zurich, Switzerland
    • Ritter, Joachim. Geophysical Institute, Universität Karlsruhe (TH), Hertzstr. 16, 76187, Karlsruhe, Germany
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:316195
    Summary
    The determination of seismic amplitude amplification is a fundamental contribution to seismic hazard assessment. While often only high-frequency amplitude variations (>1Hz) are taken into account, we analyse broadband waveforms from 0.14 to 8.6Hz using a temporary network of 32 stations in and around the earthquake-prone city of Bucharest. Spectral amplitudes are calculated with an adaptive multiple-taper approach. Across our network (aperture 25km×25km), we find a systematic northwest/southeast-oriented structural influence on teleseismic P-wave amplitudes from 0.14 to 0.86Hz that can be explained by constructive interference in the dipping Cenozoic sedimentary layers. For higher frequencies (1.4-8.75Hz), more local site effects prevail and can be correlated partly among neighbouring stations. The transition between systematic and localised amplitude variations occurs at about 1Hz