GNS Science Research Articles

A Review of 15 Years of Public Earthquake Forecasting in Aotearoa New Zealand

Abstract New Zealand entered a period of increased seismic activity in 2003, which, to date, has included around 20 large or damaging earthquakes. Building on decades of forecast model research and including research into formal model evaluation, GNS Science, the governmental institution tasked with providing natural hazards information, began issuing public earthquake forecasts following the 2009 Mw 7.2 Darfield earthquake. This article provides a review of the public earthquake forecasting methods and outcomes since that time. Initially the release of forecasts was motivated by the scientific team, but interest, use and understanding quickly rose in the public, government, and private sectors which led to regular refinement and additions to the type of forecast information provided. The basic tenet of forecasting has remained the same, with the forecasts being used to inform decisions requiring consideration of timeframes from days to decades. The operational models were all based on the previous 10–20 years of research in model development and testing; this included the development of methods for combining multiple models into a single hybrid model that typically provides increased statistical forecast skill. The hybrid models combine models from three classes of time horizons: (1) short-term aftershock clustering based on the epidemic-type aftershock sequence class of models, (2) medium-term clustering with time horizons of years to decades, and (3) long-term models with time horizons of decades to nominally time independent. Forecasts have been issued in response to 14 large or significant earthquakes with the forecasts and accompanying information regularly updated on the GeoNet webpages. An important component to the successful deployment and uptake of the models was the foundation laid in the previous decades in model development and testing. This provided understanding and confidence in the models’ ability to provide useful forecasts for response and recovery decisions.

Twenty years of volcano data at GeoNet—collection, custodianship, and evolution of open data on New Zealand’s volcanoes

The GeoNet programme at GNS Science has monitored and managed data for volcanoes, earthquakes, landslides, and tsunami in Aotearoa New Zealand since 2001. Volcano monitoring data are collected from seismometers, acoustic sensors, GNSS receivers, webcams, remote gas monitoring sensors, and a range of environmental sensors, as well as manually during visits to volcanoes. The primary user of volcano data is the internal cross-specialised Volcano Monitoring Group (VMG), which fulfils the role of the national volcano observatory. GeoNet concentrates on automatic data collection and analysis, while supporting members of the VMG with manual data collection and interpretation. The application of open-data principles to both data and metadata has always been a core aspect of GeoNet; responses have been overwhelmingly positive, despite concerns regarding some high value, manually collected datasets. The website www.geonet.org.nz represents the primary data access portal. Data analysis and delivery applications are organised by data type rather than hazard, with no volcano-specific data applications. Most datasets have web-based and API delivery application options; both provide standard data formats from a cloud-based archive. One of the challenges for volcano data collection and management has been shifting from a reliance on manually collected data to automatic collection. Additionally, awareness of important questions related to Indigenous Māori data governance is increasing, although the associated impact is not yet understood. Overall, the current centralised, cooperative volcano monitoring and data collection and management system, which benefits from improved efficiency, interoperability, and data quality, has proved effective in Aotearoa New Zealand. Ongoing work aims to ensure optimal data collection and management for volcano monitoring and downstream activities.

GSeisRT: A Continental BDS/GNSS Point Positioning Engine for Wide-Area Seismic Monitoring in Real Time

Precise coseismic displacements in earthquake/tsunamic early warning are necessary to characterize earthquakes in real time in order to enable decision-makers to issue alerts for public safety. Real-time global navigation satellite systems (GNSSs) have been a valuable tool in monitoring seismic motions, allowing permanent displacement computation to be unambiguously achieved. As a valuable tool presented to the seismic community, the GSeisRT software developed by Wuhan University (China) can realize multi-GNSS precise point positioning with ambiguity resolution (PPP-AR) and achieve centimeter-level to sub-centimeter-level precision in real time. While the stable maintenance of a global precise point positioning (PPP) service is challenging, this software is capable of estimating satellite clocks and phase biases in real time using a regional GNSS network. This capability makes GSeisRT especially suitable for proprietary GNSS networks and, more importantly, the highest possible positioning precision and reliability can be obtained. According to real-time results from the Network of the Americas, the mean root mean square (RMS) errors of kinematic PPP-AR over a 24 h span are as low as 1.2, 1.3, and 3.0 cm in the east, north, and up components, respectively. Within the few minutes that span a typical seismic event, a horizontal displacement precision of 4 mm can be achieved. The positioning precision of the GSeisRT regional PPP/PPP-AR is 30%–40% higher than that of the global PPP/PPP-AR. Since 2019, GSeisRT has successfully recorded the static, dynamic, and peak ground displacements for the 2020 Oaxaca, Mexico moment magnitude (Mw) 7.4 event; the 2020 Lone Pine, California Mw 5.8 event; and the 2021 Qinghai, China Mw 7.3 event in real time. The resulting immediate magnitude estimates have an error of around 0.1 only. The GSeisRT software is open to the scientific community and has been applied by the China Earthquake Networks Center, the EarthScope Consortium of the United States, the National Seismological Center of Chile, Institute of Geological and Nuclear Sciences Limited (GNS Science Te Pū Ao) of New Zealand, and the Geospatial Information Agency of Indonesia.

Drawing attention to attitudes toward scientists: Changes in 10- to 13-year-old students as a result of a GeoCamp experience in New Zealand

This paper reports on a two-week Earth Science programme, designed and delivered by the New Zealand Crown Research Institute of Geological and Nuclear Sciences Limited (GNS Science) referred to as the GeoCamp. This initiative has offered 10- to 13-year-old students learning experiences outside the classroom in several regions throughout New Zealand. The programme discussed in this paper was held in the Wairarapa region in the south-east of the North Island. We examined 23 students’ attitudinal changes toward scientists and science. Data collection reported in this paper occurred on the first day of the programme and six months later, when students were asked to draw annotated diagrams of scientists. Our results indicate that students participating in the camp broadened their views of scientists from being stereotypically eccentric chemists in lab coats, to those being aligned with real-world scientists, i.e. not being eccentric, some being females, some working outdoors, and being collaborative. They also recognized that scientists engage in a diverse range of work, and suggested some specific problems that they would like to solve if they were to be scientists. We suggest that these results reveal affective learning outcomes of this Education Outside the Classroom (EOTC) approach.

A continent-wide detailed geological map dataset of Antarctica

A dataset to describe exposed bedrock and surficial geology of Antarctica has been constructed by the GeoMAP Action Group of the Scientific Committee on Antarctic Research (SCAR) and GNS Science. Our group captured existing geological map data into a geographic information system (GIS), refined its spatial reliability, harmonised classification, and improved representation of glacial sequences and geomorphology, thereby creating a comprehensive and coherent representation of Antarctic geology. A total of 99,080 polygons were unified for depicting geology at 1:250,000 scale, but locally there are some areas with higher spatial resolution. Geological unit definition is based on a mixed chronostratigraphic- and lithostratigraphic-based classification. Description of rock and moraine polygons employs the international Geoscience Markup Language (GeoSciML) data protocols to provide attribute-rich and queryable information, including bibliographic links to 589 source maps and scientific literature. GeoMAP is the first detailed geological map dataset covering all of Antarctica. It depicts ‘known geology’ of rock exposures rather than ‘interpreted’ sub-ice features and is suitable for continent-wide perspectives and cross-discipline interrogation.

Towards real-time probabilistic ash deposition forecasting for New Zealand

Volcanic ashfall forecasts are highly dependent on eruption source parameters (ESPs) and synoptic weather conditions at the time and location of the eruption. In New Zealand, MetService and GNS Science have been jointly developing an ashfall forecast system that incorporates four-dimensional high-resolution numerical weather prediction (NWP) and ESPs into the HYSPLIT model, a state-of-the art hybrid Eulerian and Lagrangian dispersion model widely used for volcanic ash. However, these forecasts are based on discrete ESPs combined with a deterministic weather forecast and thus provide no information on output uncertainty. This shortcoming hinders stakeholder decision making, particularly near the geographical margin of forecasted ashfall and in areas with large gradients in forecasted ash deposition. Our study presents a new approach that incorporates uncertainty from both eruptive and meteorological inputs to deliver uncertainty in the model output. To this end, we developed probability density functions (PDFs) for three key ESPs (plume height, mass eruption rate, eruption duration) tailored to New Zealand’s volcanoes and combine them with NWP ensemble datasets to generate probabilistic ashfall forecasts using the HYSPLIT model. We show that the Latin Hypercube Sampling (LHS) technique can be used to representatively span this four-dimensional parameter space and allow us to add uncertainty quantification to rapid response forecast systems. For a case study of a hypothetical eruption at Tongariro, New Zealand we suggest that large parts of New Zealand’s North Island would not receive adequate warning for potential ashfall if uncertainties were not included in the forecasts. We also propose new probabilistic summary products to support public information and emergency responders decision making.

Evolution of Rutherford’s ion beam science to applied research activities at GNS Science

ABSTRACT This manuscript outlines current research activities based on ion beam science at GNS Science in New Zealand. Ion beam analysis methods include Rutherford backscattering and nuclear reaction analysis which trace back to Rutherford's famous ‘gold foil’ and ‘splitting the atom’ experiments. These ion beam-based methods generally offer the ability to analyse materials for every element of the periodic table, to ppm concentrations, and with depth profiles ranging from a few nm to several microns. Ion beam methods are now also used to modify and create new materials precisely. Rutherford’s early research now has a legacy at GNS Science’s Materials team to discover, design, and develop materials for energy efficient modern applications for a low carbon future. These include magnetic sensors for security products, nanostructured magnetic materials for energy conversion, thermoelectric devices for energy harvesting, and catalytic development for clean energy carriers and energy efficient communication devices.

New Zealand gravity reference stations 2020: history and development of the gravity network

ABSTRACT Gravity surveys using relative gravity meters are often tied to accessible, accurate and stable gravity reference stations. Since 1947 gravity reference networks have included pendulum gravity stations, New Zealand Primary Gravity Network stations, stations at geodetic benchmarks, base stations established by GNS Science and absolute gravity stations (since 1995). New Zealand Gravity Reference Stations 2020 is a revision of earlier gravity networks and includes precise observations made with relative meters since the 1970s that for the first time are referenced to absolute gravity measured in New Zealand. Currently there are 1710 gravity reference sites with 1475 sites classed as usable. The gravity across the network has been combined in a set of least squares calculations with an estimated uncertainty for gravity at geodetic benchmarks and GNS Science base stations of ± 0.3 µN/kg, and ± 0.6 µN/kg at New Zealand Primary Gravity Network stations. Gravity stations affected by large earthquakes since 1990 have been resurveyed, and gravity changes due to long term variations in elevation, local fluctuations in groundwater level and alteration to nearby topography from erosion and roadworks are estimated at < ± 0.3 µN/kg.

Challenges and opportunities in New Zealand seismic hazard and risk modeling using OpenQuake

The corrected 2010 New Zealand National Seismic Hazard Model has been adapted for use in the Global Earthquake Model’s OpenQuake engine through an extensive benchmarking exercise with GNS Science’s legacy Fortran code. Resolution of differences between the legacy code and OpenQuake result in hazard curve output comparisons with discrepancies of less than 3% nationally and remaining discrepancies highlight challenges faced when moving away from in-house legacy code. OpenQuake’s multiple and varied computation options for both hazard and risk and OpenQuake’s consistent, software-friendly output formats allow for exploration and development of innovative approaches to future seismic hazard and risk modeling in New Zealand. The end-to-end seismic hazard-to-risk capabilities already enabled by the inclusion of New Zealand seismic hazard, vulnerability, and building exposure models in OpenQuake have already had significant impact on post-disaster response to the 2016 Kaikōura earthquake.

Forecasting for a Fractured Land: A Case Study of the Communication and Use of Aftershock Forecasts from the 2016 Mw 7.8 Kaikōura Earthquake in Aotearoa New Zealand

Abstract Operational earthquake forecasts (OEFs) are represented as time-dependent probabilities of future earthquake hazard and risk. These probabilities can be presented in a variety of formats, including tables, maps, and text-based scenarios. In countries such as Aotearoa New Zealand, the U.S., and Japan, OEFs have been released by scientific organizations to agencies and the public, with the intent of providing information about future earthquake hazard and risk, so that people can use this information to inform their decisions and activities. Despite questions being raised about the utility of OEF for decision-making, past earthquake events have shown that agencies and the public have indeed made use of such forecasts. Responses have included making decisions about safe access into buildings, cordoning, demolition safety, timing of infrastructure repair and rebuild, insurance, postearthquake building standards, postevent land-use planning, and public communication about aftershocks. To add to this body of knowledge, we undertook a survey to investigate how agencies and GNS Science staff used OEFs that were communicated following the Mw 7.8 2016 Kaikōura earthquake in Aotearoa New Zealand. We found that agencies utilized OEFs in many of the ways listed previously, and we document individual employee’s actions taken in their home-life context. Challenges remain, however, regarding the interpretation of probabilistic information and applying this to practical decision-making. We suggest that science agencies cannot expect nontechnical users to understand and utilize forecasts without additional support. This might include developing a diversity of audience-relevant OEF information for communication purposes, alongside advice on how such information could be utilized.

Geological surveys as research-focused organizations: New Zealand's experience and opportunities

Abstract GNS Science is New Zealand's geological survey with an applied earth science research focus yet without traditional government department accountabilities. As one of New Zealand's Crown Research Institutes established in 1992, GNS Science is owned by the New Zealand Government but has higher levels of self-determination, fiscal independence and impartiality than a government department. Securing competitive research funding and commissioned research is a business imperative and because of this the institute is able to respond and adapt to changing societal expectations. GNS Science can also influence outcomes based on its discretionary research investment. New Zealand's geological setting astride an active plate boundary attracts many international partners endeavouring to better understand geological processes in an accessible and logistically well-resourced natural laboratory. Partnerships like these substantially increase technological and financial resources and these enable diverse and often ambitious projects.

Applying New Zealand’s risk tools internationally: Case studies from Samoa and Vanuatu

Decision makers require disaster risk management (DRM) tools to better prepare for and respond to emergencies, and for making sound land- use planning decisions. Risk tools need to incorporate multiple hazard and asset types, and have the versatility to adapt to local contexts. RiskScape is a natural hazards impact and loss modelling tool developed to support DRM related decision making in New Zealand. The RiskScape software has benefitted from over 10 years of research and development, and has been used for a diverse range of applications both in New Zealand and internationally. Experience and challenges in applying RiskScape beyond New Zealand are highlighted in this study through the tailoring of RiskScape for Pacific Island countries, as part of the Pacific Risk Tool for Resilience (PARTneR) project. PARTneR is a collaborative project between the National Institute of Water and Atmospheric Research (NIWA), GNS Science, the disaster management offices of Samoa and Vanuatu, and the Geoscience Division of the Pacific Community. RiskScape is applied through three demonstration case studies for each country, focused on prominent natural hazards.

OpenQuake Implementation of the Canterbury Seismic Hazard Model

ABSTRACTThis article describes the release of the GNS Science Canterbury Seismic Hazard Model (CSHM), as implemented in the Global Earthquake Model’s OpenQuake software. Time‐varying models are implemented for the 50 yr time period between 2014 and 2064, as well as the 1 yr period from 1 September 2018 to 31 August 2019. Previous implementations have been confined to GNS in‐house software, and although source model input files have been made publicly available, this implementation improves the levels of visibility, documentation, and version control. Because of practical constraints in preparing a model for routine analysis, some corrections and changes to the previous implementations have been made. These constraints highlight issues for consideration when developing future hazard models, particularly the necessity of maintaining a balance between best‐practice science and practical model implementation. By implementing the CSHM in OpenQuake, the model is now in a form that allows users to obtain model outputs for engineering design, risk analyses, and prospective model testing.

Tree ferns and tea trees in biogeochemical exploration for epithermal Au and Ag in New Zealand

Biogeochemical orientation surveys were undertaken at low sulphidation epithermal Au–Ag occurrences in the Hauraki Goldfield–Coromandel Volcanic Zone and the Taupo Volcanic Zone, and at the Waiotapu active geothermal area in the Taupo Volcanic Zone. Several plant species were sampled, including the foliage of tree ferns and tea trees. The ferns – silver fern ( ponga ), rough tree fern ( wheki ) and black tree fern ( mamaku ) – were ubiquitous and were the easiest species to sample, although tea tree was the dominant genus at Waiotapu. At the Waiotapu geothermal area, significantly higher concentrations of Ag, Au, Sb, As, Cs and Rb were present in samples close to Champagne Pool than elsewhere, confirming its location as the main outflow source of Au, Ag and their pathfinder elements. The fern survey areas at Luck at Last mine, Pine Sinter and Ohui in the Coromandel Volcanic Zone each exhibited biogeochemical anomalies, which successfully highlighted most of the known quartz veins and provided additional anomalies for further investigation. Rough tree fern was the most common species at Goldmine Hill, Puhipuhi (Taupo Volcanic Zone). Although this species absorbs lower concentrations of many elements than the silver fern, the spatial distribution of elements is of greater significance than their absolute concentrations. The highest Au, Ag, As and Al concentrations occurred in samples from a ridge extending WNW from Goldmine Hill. Sb and Bi were at anomalous levels in an area peripheral to the precious metal anomalies, indicating the potential zonation of elements distal from the Au and Ag deposits. Supplementary material: The full datasets on the fern and tea tree chemistry, including quality assurance/quality control and multi-element plots, are available free of charge through the GNS Science website (search for Dunn) at http://shop.gns.cri.nz/publications/science-reports/ .

28Si+ ion beams from Penning ion source based implanter systems for near-surface isotopic purification of silicon.

Modern computing technology is based on silicon. To date, a cost-effective and easy to implement method to obtain isotopically pure silicon is highly desirable for attaining efficient heat dissipation in microelectronic devices and for hosting spin qubits in quantum computing. We propose that it is possible to use a 28Si+ ion beam to obtain an isotopically pure near-surface region in wafer silicon. However, this requires a highly stable, high current, and isotopically pure 28Si ion beam. This work presents and discusses the instrumentation details and experimental parameters involved in generating this required ion beam. Silane is used as the precursor gas and is decomposed in a Penning ion source to generate a 28Si+ ion beam. The influence of key ion source parameters such as the gas flow rate, magnetic field strength, and anode voltage is presented. An isotopically pure 28Si+ ion beam with 10 ± 0.5 μA current on the target is obtained at the GNS Science 40 kV ion implanter. The beam was observed to be stable for at least 8 h and contains less than 700 ppm of other Si isotopes. This high current and high purity provides opportunities to explore efficient modification of the isotopic distribution in a native Si substrate at ambient temperature. The results highlight opportunities offered by using Penning ion source based low energy ion implanters for the synthesis of isotopically modified Si surface regions-a technique also applicable to other materials such as diamonds and diamond-like carbon.

Evaluating life-safety risk for fieldwork on active volcanoes: the volcano life risk estimator (VoLREst), a volcano observatory\u2019s decision-support tool

When is it safe, or at least, not unreasonably risky, to undertake fieldwork on active volcanoes? Volcano observatories must balance the safety of staff against the value of collecting field data and/or manual instrument installation, maintenance, and repair. At times of volcanic unrest this can present a particular dilemma, as both the value of fieldwork (which might help save lives or prevent unnecessary evacuation) and the risk to staff in the field may be high. Despite the increasing coverage and scope of remote monitoring methods, in-person fieldwork is still required for comprehensive volcano monitoring, and can be particularly valuable at times of volcanic unrest. A volcano observatory has a moral and legal duty to minimise occupational risk for its staff, but must do this in a way that balances against this its duty to provide the best possible information in support of difficult decisions on community safety.To assist with consistent and objective decision-making regarding whether to undertake fieldwork on active volcanoes, we present the Volcano Life Risk Estimator (VoLREst). We developed VoLREst to quantitatively evaluate life-safety risk to GNS Science staff undertaking fieldwork on volcanoes in unrest where the primary concerns are volcanic hazards from an eruption with no useful short-term precursory activity that would indicate an imminent eruption. The hazards considered are ballistics, pyroclastic density currents, and near-vent processes. VoLREst quantifies the likelihood of exposure to volcanic hazards at various distances from the vent for small, moderate, or large eruptions. This, combined with the estimate of the chance of a fatality given exposure to a volcanic hazard, provides VoLREst’s final output: quantification of the hourly risk of a fatality for an individual at various distances from the volcanic vent.At GNS Science, the calculated levels of life-safety risk trigger different levels of managerial approval required to undertake fieldwork. Although an element of risk will always be present when conducting fieldwork on potentially active volcanoes, this is a first step towards providing objective and reproducible guidance for go/no go decisions for access to undertake volcano monitoring.

Managing hazardous materials in New Zealand’s National Petrology Reference collection

ABSTRACTNew Zealand’s National Petrology Reference Collection at GNS Science includes samples of radioactive and asbestiform minerals and rocks. The legislative requirements for managing these potentially hazardous samples have recently changed because the Radiation Safety Act, Radiation Safety Regulations and Health and Safety at Work (Asbestos) Regulations were revised in 2016–2017. Steps have been taken at GNS Science to ensure legislative requirements are met, and procedures put in place to safely store and manage radioactive and asbestiform-bearing samples within the collection. These procedures may have application to other curated geological collections at New Zealand universities and museums involving potentially hazardous materials.

Life on the Wellington Fault: Managing Geological Collections and Earthquake Risk

GNS Science is home to New Zealand’s national rock, mineral and fossil collections. The National Petrology Reference Collection (NPRC) is a ‘nationally significant’ collection of rocks and minerals from on- and off-shore New Zealand, Antarctica and the rest of the world. The National Paleontological Collection (NPC) is another nationally significant collection; of fossil material from New Zealand, the South West Pacific region and Antarctica, with some overseas additions. Their status as nationally significant collections mean that GNS Science is contracted by the New Zealand Government to provide long-term collection management. Collectively, the NPC and NPRC constitute more than 200,000 samples, dating from the earliest days of New Zealand geology exploration in the late 1800s. The collections continue to grow by hundreds to thousands of samples per year, and are loaned nationally and internationally for scientific research. They are by far the largest collections of fossils, rocks and minerals housed in New Zealand, and are important earth science archives for the entire Zealandian Southern Ocean region. The collections are housed on-site at GNS Science in Lower Hutt, a few hundred meters from the surface trace of the Wellington Fault and within striking distance of other active faults that could generate major earthquakes. Best estimates suggest that the Wellington Region has an average return time of about 150 years for very strong or extreme ground shaking. Such proximity to this significant, active hazard means that steps must be taken to ensure the long-term security and integrity of the collections in the event of earthquake shaking, as well as other natural and non-natural disasters. To that end, the collection managers have written and implemented disaster mitigation, preparedness and recovery plans for the National Petrology Reference Collection and National Paleontological Collection. Here we define the earthquake hazard posed by the Wellington Fault, assess the risk to the collections, and present steps taken to manage that risk.

The location of the Pink and White Terraces of Lake Rotomahana, New Zealand

ABSTRACTThe locations of the lost Pink and White Terraces of Lake Rotomahana, New Zealand are plotted on today’s map by using sightlines in photographs of the terraces before they vanished in the volcanic eruption of 10 June 1886. Evidence is presented that the terraces could not have survived the eruption unmodified, in their original positions, at these locations. These photo sightlines and map plots add valid independent evidence to the debate about the fate of the terraces, and corroborate the finding of the 2011–2014 survey of Lake Rotomahana by GNS Science New Zealand scientists and their collaborators from Woods Hole Oceanographic Institution, USA, that the terraces did not survive the eruption intact. Evidence is presented that Dr Ferdinand von Hochstetter’s 1860s’ maps of Lake Rotomahana cannot be relied upon for accurate bearings and distances between ground features around the lake and terraces, and that, consequently, A. R. Bunn’s locations of the terraces derived from the maps are not reliable enough to support his conclusion that at least some of the terraces survived unmodified in their original position, and may be uncovered by excavation.

Evaluating the impacts of volcanic eruptions using RiskScape

RiskScape is a free multi-hazard risk assessment software programme jointly developed by GNS Science and the National Institute of Water and Atmospheric Research (NIWA) in New Zealand. RiskScape has a modular structure, with hazard layers, assets, and loss functions prepared separately. While RiskScape was originally developed for New Zealand, given suitable hazard and exposed asset information, RiskScape can be run anywhere in the world. Volcanic hazards are among the many hazards considered by RiskScape. We first present RiskScape’s framework for all hazards, and then describe in more detail the five volcanic hazards – tephra deposition, pyroclastic density currents, lava flows, lahars, and edifice construction/excavation. We describe how loss functions were selected and developed. We use a scenario example to illustrate not only how RiskScape’s volcanic module works but also how RiskScape can be used to compare across natural hazards.