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Influence of Site Effects on Observed Ground Motions in the Wellington Region from the Mw 7.8 Kaikōura, New Zealand, Earthquake

2018; Seismological Society of America; Volume: 108; Issue: 3B Linguagem: Inglês

10.1785/0120170286

1943-3573

Brendon Bradley, Liam Wotherspoon, Anna Kaiser, Brady R. Cox, Seokho Jeong,

earthquake and tectonic studies

Research Article| March 13, 2018 Influence of Site Effects on Observed Ground Motions in the Wellington Region from the Mw 7.8 Kaikōura, New Zealand, Earthquake Brendon A. Bradley; Brendon A. Bradley aDepartment of Civil and Natural Resource Engineering, University of Canterbury, Private Bag 4800, Christchurch 8014, New Zealand, brendon.bradley@canterbury.ac.nz Search for other works by this author on: GSW Google Scholar Liam M. Wotherspoon; Liam M. Wotherspoon bDepartment of Civil and Environmental Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand Search for other works by this author on: GSW Google Scholar Anna E. Kaiser; Anna E. Kaiser cTectonophysics Department, GNS Science, P.O. Box 30‐369, Lower Hutt 5040, New Zealand Search for other works by this author on: GSW Google Scholar Brady R. Cox; Brady R. Cox dDepartment of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712 Search for other works by this author on: GSW Google Scholar Seokho Jeong Seokho Jeong eQuakeCoRE, University of Canterbury, Private Bag 4800, Christchurch 8014, New Zealand Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2018) 108 (3B): 1722–1735. https://doi.org/10.1785/0120170286 Article history first online: 13 Mar 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Brendon A. Bradley, Liam M. Wotherspoon, Anna E. Kaiser, Brady R. Cox, Seokho Jeong; Influence of Site Effects on Observed Ground Motions in the Wellington Region from the Mw 7.8 Kaikōura, New Zealand, Earthquake. Bulletin of the Seismological Society of America 2018;; 108 (3B): 1722–1735. doi: https://doi.org/10.1785/0120170286 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract This article presents ground‐motion and site‐effect observations in the Wellington region of New Zealand from the 14 November 2016 Mw 7.8 Kaikōura earthquake. Despite being ∼60 km from the northern extent of the causative earthquake rupture, amplification of long‐period ground motions due to site and basin‐edge effects resulted in appreciable ground motions and subsequent damage to the built environment in this major urban area and capital city of New Zealand. The largest long‐period ground motions were observed in the Thorndon and Te Aro basins in central Wellington, where similar site amplification effects were also observed during the 2013 Cook Strait earthquake sequence. Comparisons of pseudoacceleration response spectra with current estimates of fundamental site period across central Wellington indicate that this long‐period amplification, relative to nearby rock stations, cannot be explained by 1D site effects alone (i.e., layered impedance), and thus it is inferred that there is a significant contribution from basin‐edge‐generated surface waves. In contrast, in the Lower Hutt–Petone area, north of central Wellington, ground motions from the GeoNet strong‐motion station array across a deep alluvial valley clearly demonstrate the influence of 1D site effects. The 5%–95% significant duration of ground motions in central Wellington was on the order of 30 s, consistent with empirical models for this earthquake magnitude and source‐to‐site distance. The observations from the 2016 Kaikōura earthquake and comparison with the ground‐motion characteristics of recent earthquakes has highlighted the need to improve characterization of the regional basin structures, particularly in regard to quantifying the contribution of basin resonance and basin‐edge‐generated surface waves. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.