| Autor: |
Opršal, Ivo, Halló, Miroslav, Fäh, Donat, Burjánek, Jan |
| Jazyk: |
angličtina |
| Rok vydání: |
2022 |
| Předmět: |
|
| Popis: |
The high-frequency (>1Hz) surface-to-depth spectral amplification is one of the key features of site response characterization relating ground motion at depth and on the surface. This site-specific transfer function can be retrieved for sites with borehole monitoring arrays by computing surface-to-borehole spectral ratios for multiple records of regional earthquakes (i.e. empirical S/B ratios). Nevertheless, modelling and predictions are challenging due to limited knowledge of the heterogeneous near-surface velocity structure, and due to the complexity of the impeding high-frequency near-surface wave-field. Moreover, modelling of simple SH-wave depth-to-surface transfer function in 1D medium produces distinctive narrow spectral peaks of high amplitudes unobserved in empirical data. Recently, a novel stochastic model has been introduced for 1D media providing a good fit to empirical data in the broad frequency range for sites with 1D resonance effects. In this contribution, we introduce a strategy for modelling the surface-to-depth amplification in 3D media using a finite-difference method. The finite-difference numerical modelling is done for fine 3D subsurface structures with smoothed boundaries and random heterogeneities, which results in surface-to-depth amplification functions without unrealistic spectral peaks. The final comparison of our prediction of amplification to real data is made for KiK-net stations with empirical S/B ratios indicating the presence of either 1D or complex site effects characterizing a particular site. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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