• Login
    View Item 
    •   NZSEE Document Repository
    • New Zealand Society for Earthquake Engineering
    • Proceedings of the 2024 New Zealand Society for Earthquake Engineering Annual Technical Conference
    • View Item
    •   NZSEE Document Repository
    • New Zealand Society for Earthquake Engineering
    • Proceedings of the 2024 New Zealand Society for Earthquake Engineering Annual Technical Conference
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Shallow Shear Wave Reflection Surveys in the Wellington CBD

    Thumbnail
    Download
    PDF (1.172Mb)
    Date
    2024-04-09
    Authors
    Thorpe-Loversuch, Sam
    Stern, Tim
    Stratford, Wanda
    Metadata
    Show full item record
    Abstract
    Seismic reflection profiles using shear waves provide constraints on the thickness of sediments beneath the Wellington CBD. New shear wave source and acquisition methods were trialled for use in urban environments to investigate shallow sedimentary basins. Converting the two-way travel time axis on the stacked seismic section to depth required a velocity model for each location based on direct velocity measurements made from local downhole seismic logs. Basement depths at Wellington Girls College and Waitangi Park are estimated to be 180 ± 19 and 220 ± 25 m, respectively. These depths are up to 77% greater than previous estimates based on gravity modelling, 3D mapping of borehole depths, and microtremor analysis. At Wellington Girls College, near-surface sediments are horizontally layered, whereas, at Waitangi Park, sediment and basement offsets are interpreted. These offsets are attributed to the Aotea Fault, which is interpreted as a complicated, three-step, laddered structure. A near-surface seismic survey was undertaken at Miramar Polo Ground, where a logged borehole allowed us to benchmark our interpretations against the subsurface geology. These new estimates of basement depth in the Wellington Basin will provide constraints for geological models that predict how shaking from earthquakes will vary across the city due to variations in the basin’s depth and shape.
    URI
    https://repo.nzsee.org.nz/handle/nzsee/2726
    Published in
    • Proceedings of the 2024 New Zealand Society for Earthquake Engineering Annual Technical Conference

    Contact Us | Send Feedback
     

     

    Browse

    Entire RepositoryCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login

    Contact Us | Send Feedback