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On 5 March 2021, at 2.27 AM local time (4 March 2021, 13:27:34 UTC), a Mw 7.3 earthquake woke up the North Island of New Zealand with strong and long shaking. Its epicentre was located about 170 km NE offshore Gisborne in the Hikurangi subduction zone. This was the first tsunami of a triplet occurring on the same day. The tsunami propagated from the source region to the north shore of New Zealand, with a very localised and limited impact. Maximum amplitudes of ~32.3 cm and ~6.6 cm were respectively recorded at East Cape (LOTT) and North Cape (NCPT) coastal tsunami gauges, located ~105 km and ~660 km away from the epicentre. At 6.41 AM (17:41:23 UTC), 4 hours and 14 minutes later, another earthquake triggered a tsunami in the southwestern Pacific region with a magnitude Mw 7.4 earthquake. This was located further north (~ 900 km) than the previous one, 50 km south of Raoul Island (New Zealand) on the Kermadec subduction zone. At 8.28 AM (19:28:33 UTC), 1 hour and 47 minutes later, a Mw 8.1 earthquake occurred very close to the earlier Mw 7.4 earthquake, 80 km southeast of Raoul Island. It triggered a third tsunami that was recorded on New Zealand DART stations and coastal gauges, and all around the Pacific Ocean. Those data presents the arrival times and amplitudes of the first and third tsunamis on the New Zealand coastal gauges. DOI: https://doi.org/10.21420/P606-J332 Cite data as: GNS Science. (2021). Pacific Ocean sea-level records of the 5 March 2021 triplet of tsunamis [Data set]. GNS Science. https://doi.org/10.21420/P606-J332
This report and associated data presents a new and provisional estimate of the maximum depth of rupture on New Zealand’s active faults (“New Zealand Fault-Rupture Depth Model v1.0”) based on a combination of two independent models. The first model uses regional seismicity distribution from a relocated earthquake catalogue to calculate the 90% seismicity cut-off depth (D90) representing the seismogenic depth limit H. This is multiplied by an overshoot factor representing dynamic propagation of rupture into the conditional stability zone and accounting for the difference between regional seismicity depths and frictional properties of a mature fault zone, to arrive at rupture depth Df. The second model uses surface heat-flow and rock type to compute thermal stability limits for seismogenic faults. These limits are also multiplied by an overshoot factor to arrive at a thermally-based maximum rupture depth Df. Both models have depth cut-offs at the Moho and/or subducting slabs. Results indicate maximum rupture depths between 8 km (Taupō Volcanic Zone) to > 30 km (e.g. southwest North Island), strongly correlated with regional thermal gradients. Preliminary estimates of uncertainties for each model are also discussed. Depths from the two models show broad agreement for most of the North Island and some differences in the South Island. A combined model using weighting based on relative uncertainties is derived and validated using constraints from hypocentre and slip model depths from recent well-instrumented earthquakes. (auth) DOI: https://doi.org/10.21420/0BBW-V059 Cite data as: Ellis SM, Bannister S, Van Dissen RJ, Eberhart-Phillips D, Holden C, Boulton C, Reyners ME, Funnell RH, Mortimer N, Upton P. 2021. New Zealand Fault Rupture Depth Model v1.0: a provisional estimate of the maximum depth of seismic rupture on New Zealand’s active faults. Lower Hutt (NZ): GNS Science. 47 p. (GNS Science report; 2021/08). doi:10.21420/4Q75-HZ73. (with data set available at DOI: https://doi.org/10.21420/0BBW-V059)
The Cape Egmont Fault Zone in the southern Taranaki Basin, New Zealand, is a complex series of synthetic and antithetic dip-slip normal faults accommodating present-day extension. The fault zone comprises new and reactivated faults developed over multiple phases of plate boundary deformation during the last 100 Myrs. The fault zone is well imaged on petroleum industry seismic reflection data, with a number of faults exposed and studied onshore. The Cape Egmont Fault Zone is seismically active, with damaging historic earthquakes of up to MW 5.4. Most earthquakes occur beneath the Late Cretaceous to Holocene sedimentary sequence at depths greater than 5–8 km. The maximum depth of fault rupture is c. 20 km, above which 90% of recorded earthquakes occur. Focal mechanisms from these earthquakes generally indicate strike-slip to oblique-normal faulting, which contrasts with the predominantly dip-slip faulting observed in the overlying sedimentary sequence and surface fault traces. Data from regional earthquake studies and petroleum well deformation show faults imaged in the sedimentary sequence to be preferentially oriented for slip in the present-day stress field. The greatest earthquake risk is on major basement-penetrating crustal-scale faults greater than 20 km in length. Fault lengths and maximum vertical offsets of the sedimentary sequence, determined from a three-dimensional structural model, are consistent with global displacement-length scaling relationships. This validation permits fault lengths to be used to determine potential future earthquake magnitudes using global fault length-magnitude relationships. Fault lengths of post-Pliocene normal faults are typically ≤21 km, resulting in maximum predicted magnitudes MW 6.3. The most likely earthquake magnitude from the fault population sampled is MW 5.4 ± 0.5. The largest and most mature fault – the Cape Egmont Fault – is at least 53 km long and, depending on the number of segments ruptured during a future event, is capable of generating an earthquake between MW 7 and 7.3. DOI: https://doi.org/10.21420/ED9K-EP20 Cite data as: Seebeck H, Thrasher GP, Viskovic GPD, Macklin C, Bull S, Wang X, Nicol A, Holden C, Kaneko Y, Mouslopoulou V, Begg JG. 2021. Geologic, earthquake and tsunami modelling of the active Cape Egmont Fault Zone. Lower Hutt (NZ): GNS Science. 370 p. (GNS Science report; 2021/06). doi:10.21420/100K-VW73. (with data available at DOI: https://doi.org/10.21420/ED9K-EP20)
The Aquifer Potential Map is a preliminary map (version 1.0). This work was carried out as part of the GNS Science Groundwater Resources of New Zealand research programme, and future plans within this research programme include the refinement and update of this map. In its current form, the map is considered suitable for refining surficial aquifer boundaries on the regional scale where these boundaries have not been updated since 2001. Future updates of the dataset will reduce the uncertainty and extend the applicability of the data set. The New Zealand 1:250,000 geological map (QMAP) lithological and chrono-stratigraphic information (i.e., main rock type; geological age; and secondary rock type) were used to carry out a nationwide assessment of surficial hydrogeological units and their properties. A number of subsequent map products were produced. The work is described in Tschritter et al. 2017. One of these, the Aquifer Potential map, shows a good match with the most recent New Zealand national aquifer boundary dataset of Moreau and Bekele (2015). Additionally, the Aquifer Potential map provides a quick and simple way to communicate basic large-scale hydrogeological information. DOI: https://doi.org/10.21420/4KJH-5Z44 Cite data as: GNS Science. (2017). New Zealand Aquifer Potential Map Version 1.0 [Data set]. GNS Science. https://doi.org/10.21420/4KJH-5Z44 Cite report as: Tschritter, C.; Westerhoff, R.S.; Rawlinson, Z.J.; White, P.A. 2017 Aquifer classification and mapping at the national scale - phase 1 : identification of hydrogeological units. Lower Hutt, N.Z.: GNS Science. GNS Science report 2016/51. 52 p.; doi: 10.21420/G2101S [Link to electronic copy]
This database documents fluctuations in the Earth's regional (New Zealand) magnetic field measured before the age of digital records. New Zealand operates magnetic observatories in Canterbury (the Eyrewell Geomagnetic Observatory located at West Melton) and Scott Base in Antarctica, and supports the Apia observatory in Samoa. Observatories in the present days provide a record of temporal changes of the magnetic field, recording the three components of the magnetic field every second. Eyrewell (EYR), Scott Base (SBA) and Apia (API) geomagnetic observatories.
This hydrogeological system GIS dataset provide a nationally-consistent basis for hydrogeological mapping in New Zealand. Hydrogeological systems are defined here as geographical areas with broadly-consistent hydrogeological properties, and similar resource pressures and management issues. The ‘NZ_hydrogeologicalsystem_polygon.shp’ provides seven hydrogeological attributes as follows: unique name (HS_name), unique identification (HS_id), system type (HS_type), coastal information (HS_coast), aquifer overview (HS_overview), geology and age group (HS_geo_gr) and geology and age descriptor (HS_geo_age). Nine system types are identified (see figure below). The ‘NZ_hydrogeologicalsystem_boundary.shp’ attribute table identifies, the source and methods of boundary delineation. Attribute names, descriptions and values for both datasets are detailed in Moreau et al. 2019. DOI: https://doi.org/10.21420/HTZ8-Z141 Cite as: GNS Science. (2018). New Zealand Hydrogeological Systems [Data set]. GNS Science. https://doi.org/10.21420/HTZ8-Z141
This dataset contains age tracer concentrations as measured in NZ groundwater samples through time. Tracers include Tritium, SF6, CFCs, Halon-1301. These tracer concentrations enable estimation of groundwater residence time, using mixing models to convolute input to output concentrations through hydrologic systems (e.g. aquifer, river catchment). Data are continuously added, to cover more areas, and because time series data improve the robustness of age interpretation DOI: https://doi.org/10.21420/JEBK-5288 Cite as: GNS Science. (2021). Groundwater age tracer data set [Data set]. GNS Science. https://doi.org/10.21420/JEBK-5288
This data set provides an update of New Zealand’s depth to hydrogeological basement map. Depth to hydrogeological basement can be loosely defined as the ‘base of aquifers’; or more strictly as ‘the depth to where primary porosity and permeability of geological material is low enough such that flued volumes and flow rates can be considered negligible’. For more detail on the process and methods, see Westerhoff et al. (2019). New Zealand groundwater atlas: depth to hydrogeological basement. Lower Hutt (NZ): GNS Science. 19 p. Consultancy Report 2019/140. DOI: https://doi.org/10.21420/FQXD-VY44 Cite data as: GNS Science. (2019). Depth to hydrogeological basement [Data set]. GNS Science, Ministry for the Environment. https://doi.org/10.21420/FQXD-VY44 Cite report describing the data as: Westerhoff et al. (2019). New Zealand groundwater atlas: depth to hydrogeological basement. Lower Hutt (NZ): GNS Science. 19 p. Consultancy Report 2019/140.
The Urban Borehole Database (UBHDB) is a digital compilation of borehole records utilised in urban mapping, 3D geological modelling, and ground shaking studies by GNS Science. This database primarily utilises borehole records from the New Zealand Geotechnical Database (NZGD, www.nzgd.org.nz) and other records provided to GNS Science from engineering consulting companies as well as local government records. The UBHDB is a relational database and contains nine tables; eight down-hole data tables linked to a borehole location / collar table. Down-hole data includes: lithology (descriptions from borehole logs and interpretations of local formation for each down-hole interval), geochronology, shear vein tests, SPT (standard penetration test), structure (structural measurements), survey (borehole orientation), velocity (shear wave velocity), water (static water level measurements). Addition of new data is ongoing and the database is regularly maintained and used for hazard and mapping projects at GNS Science. Data from the NZGD are added to the database in areas of mapping and modelling projects; PDF records from the NZGD are digitised and appended to the database for use in GNS Science research projects. DOI: https://doi.org/10.21420/XHB0-M968 Cite as: GNS Science. (2021). Urban Borehole Database [Data set]. GNS Science. https://doi.org/10.21420/XHB0-M968
This dataset contains Ground Penetrating Radar (GPR) data acquired by GNS Science for investigations into the shallow subsurface. The majority of data has been acquired using a PulseEKKO GPR system from Sensors & Software, and the survey data (and its associated metadata) are stored in their propriety .GPZ format. This format can be read using the EKKO_Project software package. Spatial data associated with each survey, outlining where the data was acquired, is stored as a .KML file, and can be viewed using Google Earth. Interpretation data may be available for some surveys, and this is generally stored in .CSV files. DOI:https://doi.org/10.21420/QXX6-3Y27 Cite Data as: GNS Science. (2022). Ground Penetrating Radar (GPR) [Data set]. GNS Science. https://doi.org/10.21420/QXX6-3Y27