More faults, more resolution, more featuresthe NZ Active Faults Database webmap gets a major upgrade
Those wanting to know where ground surface rupturing is most likely to occur in New Zealand following a large earthquake will now have even better and more detailed information thanks to an upgrade to the GNS Science New Zealand Active Faults Database (NZAFD) webmap.
The webmap(external link) now includes a high-resolution (1:10,000 scale or better) active fault surface trace layer for some regions – 25 times greater resolution than the existing 1:250,000 scale layer available on the webmap. This means thousands more active fault traces can now be viewed right down to the property scale.
It is expected the upgrade will be particularly useful for councils but also hazard planners, infrastructure industry, geotechnical practitioners, researchers and homeowners to better understand the potential location of surface fault ruptures during future large earthquakes, at a relevant scale.
The webmap also includes Fault Avoidance Zones and Fault Awareness Areas for the high-resolution active fault layer, where available, which are important for land-use planning.
While the high-resolution data is currently only available for Hawke’s Bay, Manawatū-Whanganui (Horizons) and Wellington regions, more areas will be added as funding permits and work progresses.
Active fault surface traces are visually identifiable at the earth surface and indicate areas prone to fault rupture during a large earthquake.
The NZAFD comprises lines showing onshore active fault surface traces – defined as those that have ruptured and/or caused ground surface deformation during the last 125,000 years*. Each fault trace also includes attributes that describe the expected rupture frequency, slip rate, last known event and other parameters useful for risk assessments, where available.
Some active faults well known to people, such as the Port Hills (2011 Christchurch earthquake) and Awanui (1931 Napier earthquake) faults, do not appear on the NZAFD webmap as these are buried active faults that have not ruptured the ground surface and have no surface expression.
The Fault Avoidance Zones delineate and mitigate the areas of surface rupture hazard, through the application of the Ministry for the Environment Active Fault Guidelines(external link), while Fault Awareness Areas(external link) highlight the areas where a surface rupture hazard may exist and more information is required.
While many of the high-resolution datasets are currently available on respective regional and local council digital platforms, the enhanced GNS webmap makes this information available in a single publicly accessible location accessed on a visually interactive platform. Associated reports can also be downloaded for the high-resolution layers via pop-ups in the GNS webmap, where available.
Users of this GNS webmap will see consistent symbology and attribute information, making it a trusted, up-to-date and consistent source of truth for active faults in New Zealand.
Other enhancements users will see are more regular updates of the existing 1:250,000 scale dataset that can be downloaded, along with more explanatory information (metadata) about each dataset and how it can be used.
*Except for in the Taupō Rift, where the definition of activity is restricted to include only the last 25,000 years