Mapping Depth to Bedrock, Shear Stiffness, and Fundamental Site Period at CentrePort, Wellington using Surface Wave Methods: Implications for Local Seismic Site Amplification
| Autor: | Liam Wotherspoon, Brady R. Cox, Joseph P. Vantassel, Andrew Stolte |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
021110 strategic
defence & security studies geography geography.geographical_feature_category Shear stiffness Bedrock 0211 other engineering and technologies FOS: Physical sciences 02 engineering and technology 010502 geochemistry & geophysics 01 natural sciences Geophysics (physics.geo-ph) Physics - Geophysics Geophysics Geochemistry and Petrology Surface wave Period (geology) Geology Seismology 0105 earth and related environmental sciences |
| Popis: | Wellington's port (CentrePort) experienced significant damage from the $M_w$ 7.8 Kaikōura earthquake as a result of soil liquefaction, lateral spreading, and shaking-induced damage to structures. To investigate these ill effects, and propose mitigation measures to prevent similar damage in future earthquakes, there was a need to quantify the variations in the depth to bedrock, shear stiffness, and fundamental site period ($T_0$) across the port. In order to characterize $T_0$ and develop shear wave velocity (Vs) profiles for use in seismic site response analyses, horizontal-to-vertical (H/V) spectral ratio measurements and active-source and passive-wavefield surface wave testing (i.e., MASW and MAM, respectively) were performed across the port. A site period map developed from 114 H/V spectral ratio measurements indicates several areas of rapidly changing, complex subsurface structure. Deep (200-plus meters) Vs profiles developed at six reference locations across the port were used to estimate the depth to soft (Vs $>$ 760 m/s) and hard (Vs $>$ 1500 m/s) rock. $T_0$ estimates from H/V spectral ratio measurements ($T_{0,H/V}$) at the six reference locations are shown to be related to the depth of hard rock based on linear viscoelastic transfer functions calculated from Vs profiles truncated at several depths. $T_{0,H/V}$ measurements at two ground motion stations near the port are also shown to be in reasonably good agreement with predominant periods of maximum spectral amplification recorded during both the 2016 Kaikōura and 2013 Cook Strait earthquakes, despite these sites also being effected by soil nonlinearity and potential 3D basin edge effects. Main: 21 pages, 11 figures; Appendix: 8 pages, 6 figures; Final accepted manuscript of Vantassel et al. (2018) published in Bulletin of the Seismological Society of America, released in compliance with Seismological Society of America's green open access policy |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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