Litchfield NJ, Humphrey J, Morgenstern R, Langridge RM, Coffey GL, Van Dissen RJ. 2022. New Zealand Paleoseismic Site Database: design and overview of version 1.0. Lower Hutt (NZ): GNS Science. 27 p. (GNS Science report; 2021/52). doi:10.21420/VTPT-KB52.
Abstract
The New Zealand Paleoseismic Site Database (new term, new database) contains paleoseismic data (grouped into Slip Rate, Earthquake [EQ] Timings and Recurrence Interval [RI], and Single-Event Displacement [SED]) collected at specific sites along active faults throughout New Zealand. The database was developed as part of the New Zealand National Seismic Hazard Model 2022 Revision Project (NSHM 2022). The primary purpose is to compile paleoseismic data at specific sites to be used either as inputs into, or to constrain/validate outputs from, the Seismicity Rate Model. This report describes the purpose and design of the database, as well as the compilation process and contents of the first edition (Version 1.0). The New Zealand Paleoseismic Site Database has two components: a Microsoft Excel spreadsheet, which is a stand-alone database and the focus of this report, and a Geographic Information System (GIS) feature class dataset that is a subset of, and is intended to be entered back into, the AF.Points (Active Fault Point features) layer in the Active Faults Database of New Zealand. The Excel Slip Rate worksheet was initially adapted from the UCERF3 Geologic-Slip-Rate Data spreadsheet, and the EQ Timings RI and SED worksheets were adapted from the Slip Rate worksheet. Each worksheet has a high-level division into two sets of attributes – Fault Data and Site Data. The Fault Data attributes pertain to faults in the New Zealand Community Fault Model (CFM) and are the data most likely to be used for the Seismicity Rate Model. The Site Data component includes the site-specific data, and a site is defined as a location where paleoseismic data, generally field data, has been obtained. A site must therefore have a grid reference, but some published combined records are also included where data from two or more sites have been aggregated (e.g. a composite earthquake record derived from two or more trench sites). Most rows in the spreadsheet are therefore Site Data, but, in the EQ Timings RI worksheet, each row is an inferred earthquake. The definitions, formats and guidelines for compiling each attribute in both the Excel spreadsheet and GIS feature class are described in a companion Data Dictionary (Litchfield 2022). Version 1.0 of the New Zealand Paleoseismic Site Database was compiled by NL, JH, RM, RL and GC in 2020 and 2021, with input from RVD and other members of the New Zealand paleoseismology community. Version 1.0 contains both published and unpublished data, mostly onshore, and many sites were relocated using high-resolution Light Detecting and Ranging (LiDAR) Digital Elevation Models and orthophotos. The total number of sites is 2136, with 68 combined records, which have a reasonable geographic spread, particularly across onshore faults with slip rates of ≥1 mm/yr. The Slip Rate worksheet contains 862 sites situated on 189 CFM faults. The EQ Timings RI worksheet contains 304 sites and 953 records (earthquakes and combined records), situated on 99 CFM faults. The EQ Timings RI worksheet also includes Last Event (314) and previously documented (Reported) RI (100) records. Ninety-nine EQ Timings sites have three or more earthquakes that are currently being used for RI calculations in the NSHM 2022. The SED worksheet contains 970 sites and 17 combined records, situated on 90 CFM faults. The majority of SED sites are field-based displacement measurements for historical earthquakes, dominated by the 2010 Darfield and 2016 Kaikōura earthquakes. Version 1.0 is considered as complete as possible in the time available for data compilation, but there are known data that could be compiled in future versions, including student theses and data currently being obtained and published. New versions are contingent upon funding but could be partial (e.g. regional) or full (~5 yearly?) updates. Two known issues that could be addressed in future versions are calibration of radiocarbon ages with consistent calibration curves and inclusion of more SED data from cumulative displacements. (The authors)
For additional data please go to https://doi.org/10.21420/QFNX-0M28
