University of Waikato's CT Scan Breakthrough Uncovers Waikato's Seismic Past
The University of Waikato has pioneered a world-first technique using medical computed tomography (CT) scanners to peer into the prehistoric earthquake history of the Hamilton Basin. By analyzing 161 sediment cores extracted from 18 lakes dating back 15,700 years, researchers identified tephra seismites—distinctive layers of volcanic ash liquefied and deformed by strong ground shaking. These disturbances, preserved like natural seismographs in the mud, reveal evidence of at least five earthquakes generated by local hidden faults, including three with magnitudes of 7 or greater. Two of these powerful events occurred within the last 1,800 years, suggesting strong shaking impacts the region roughly every 3,000 years on average.
Leading the charge is Emeritus Professor David Lowe, alongside geoscientists Dr. Max Kluger, Dr. Vicki Moon, and Dr. Tehnuka Ilanko. Collaborators from Earth Sciences New Zealand (ESNZ), the University of Auckland, I-MED Hamilton Radiology, and Swansea University (UK) contributed expertise. The sediment cores, carefully preserved to maintain layering, were scanned at I-MED by radiographer Nic Ross, producing 3D digital images that allowed precise measurement of seismite dimensions. This innovation not only maps fault activity but also refines liquefaction analysis, crucial for assessing infrastructure vulnerability in sedimentary basins like Hamilton's.
The faults implicated include the buried Kūkūtāruhe and Te Tātua ō Wairere in Hamilton lowlands, Te Puninga and Kerepehi in Hauraki Plains, and a possible new one near Te Awamutu. Previously considered low-risk, the Waikato-Hauraki area now shows capability for moderate to large quakes, prompting updates to New Zealand's National Seismic Hazard Model.
LiDAR Illuminates Seven New Faults in Wairarapa Valley
High-resolution Light Detection and Ranging (LiDAR) technology—airborne laser scanning that strips away vegetation digitally—has exposed seven previously unknown active faults in the Wairarapa Valley. Among them, the 26-kilometer Pāpāwai Fault stretches from Morison Bush south of Greytown, crossing key transport routes with a multi-meter-wide disturbance zone hinting at complex rupture across smaller fractures. Four of these faults lie near population centers, underscoring urban risks.
GNS Science and ESNZ led the mapping, building on the New Zealand Active Faults Database. Trenching confirmed the Pāpāwai Fault's activity, with carbon-dated organic materials bracketing past ruptures. Dr. Graham Leonard, ESNZ principal scientist, emphasizes that such discoveries refine multi-fault rupture scenarios, vital for southern North Island kinematics. Future trenching near Masterton will date the latest events, enhancing regional hazard assessments.
This LiDAR application exemplifies how geospatial tools, often used in environmental monitoring, now bolster seismic safety. For New Zealand universities, it highlights interdisciplinary geoscience programs training the next generation of fault mappers.
Probing Auckland's Subsurface: Dozens of Potential Faults Lurk Below
Beneath New Zealand's largest city, analysis of thousands of borehole logs from infrastructure projects has pinpointed one to two dozen potential fault structures. Likely candidates cluster near Pukekohe and Drury, south of Auckland, where trenching will soon expose offsets in soil layers for carbon dating. A University of Auckland study recently detected five times more small earthquakes under the city, mapping over 35 hidden faults and underscoring that even low-seismicity zones harbor surprises—like the 1891 M6.9 Port Waikato quake that shattered Auckland windows.
ESNZ coordinates these efforts, integrating data into probabilistic hazard models. While a major Auckland quake remains unlikely short-term, long-term planning for buried faults informs skyscraper foundations and transport networks. Aspiring geologists at Auckland universities can pursue research jobs in urban seismology, blending engineering geology with public safety.
Understanding the Science: How LiDAR and CT Scans Work Step-by-Step
LiDAR (Light Detection and Ranging) involves aircraft emitting millions of laser pulses to measure ground elevation beneath forests or urban sprawl. Digital elevation models highlight subtle scarps—linear rises or drops signaling fault offsets—as small as centimeters over kilometers.
- Aircraft flies at low altitude, capturing 20-50 points per square meter.
- Vegetation removed algorithmically, revealing bare-earth topography.
- Field verification via trenching confirms scarps as faults.
CT scans, borrowed from medicine, rotate X-ray sources around sediment cores, generating 3D density maps. Tephra layers (ash from eruptions like Taupō's 232 AD VEI7 blast) liquefy during quakes above magnitude 6, folding into seismites detectable at resolutions finer than traditional X-rays.
- Extract intact cores via piston corers from lake beds.
- Scan on medical CT beds for cross-sections.
- Quantify deformation to estimate shake intensity and source faults.
These non-invasive tools democratize paleoseismology, previously reliant on costly digs.Read the Waikato study in Science Advances.
Photo by TheRegisti on Unsplash
Key Researchers Driving New Zealand's Seismic Discoveries
New Zealand's universities anchor this research. At Waikato, Prof. David Lowe's expertise in tephrochronology—dating via ash layers—pairs with Dr. Max Kluger's paleoseismology. Dr. Vicki Moon specializes in basin hazards, while Dr. Tehnuka Ilanko analyzes seismic stratigraphy. Former PhD student Dr. Jordanka Chaneva examined cores hands-on.
ESNZ's Dr. Graham Leonard oversees integration, warning, "You can still have a big earthquake anywhere in Aotearoa." Dr. Pilar Villamor links faults to tectonics. University of Auckland contributes urban fault mapping, fostering collaborations that train postdocs and PhDs.
Such teams exemplify higher education's role in national resilience. Explore university jobs in New Zealand for geoscience roles at institutions like Waikato and Auckland.
Implications for Public Safety and Infrastructure Resilience
Hidden faults challenge assumptions in low-quake zones. Waikato's every-3,000-year shaking threatens liquefaction-prone sediments under Hamilton's growing suburbs. Wairarapa faults cross SH2 and rail, risking multi-fault cascades. Auckland's buried structures demand reevaluated building codes.
Updates to the National Seismic Hazard Model incorporate these, guiding earthquake-prone building upgrades and lifeline standards. Lessons from Christchurch 2011—$40 billion damage from an unknown fault—underscore preparation. Universities like Waikato now inform resilient design, from hospitals to faculty research labs.
GNS Active Faults Database tracks progress.Integrating Fault Data into National Hazard Models
New Zealand's Community Seismic Hazard Model aggregates fault parameters—slip rates, recurrence intervals—into probabilistic forecasts. Waikato's CT data adds prehistoric events, boosting accuracy for 50-2500 year horizons. Wairarapa's seven faults refine Wellington region's multi-rupture probabilities.
ESNZ and GNS lead, with unis providing paleodata. This informs insurance, zoning, and retrofits, reducing economic losses projected at billions per major event. For students, it's a gateway to impactful modeling careers via higher ed career advice.
Taupō's Twin Threat: Faults and Volcanoes Interacting
Near Taupō, research probes fault slips coinciding with the 232 AD super-eruption, suggesting seismic-volcanic feedback. Stress from quakes may trigger magma ascent, amplifying hazards in the Volcanic Zone.
University collaborations extend CT/LiDAR methods here, monitoring interactions that could devastate Rotorua-Taupō corridor.
Photo by Scott Blake on Unsplash
Careers in Seismic Research: Opportunities at NZ Universities
Breakthroughs like Waikato's demand skilled geoscientists. Roles span paleoseismology, geospatial analysis, to hazard modeling. Universities offer PhDs, postdocs, and lectureships; GNS hires for fieldwork.
- Skills: GIS, CT imaging, trenching, tephrochronology.
- Entry: Earth Science degrees from Auckland, Waikato, Victoria.
- Impact: Shape safer communities.
Check higher ed research jobs, university jobs, or postdoc positions for openings. Platforms like Rate My Professor help choose mentors.
Future Outlook: Expanding Techniques Nationwide and Globally
Waikato's CT method eyes Auckland, Taranaki, Hawke's Bay, and international sites like Japan. LiDAR coverage grows via LINZ data. Integrated models predict cascades, aiding climate-resilient planning amid rising populations.
New Zealand universities position as seismic innovation hubs, attracting global talent. Proactive research minimizes tomorrow's disasters.
For career guidance, visit higher ed career advice. Explore higher ed jobs or university jobs in geohazards. Share insights on Rate My Professor.
