University of Waikato researchers have found significantly more fault lines under Hamilton City than previously known.
Earlier studies found evidence for deep faults within the Hamilton Basin, and excavation in 2015 uncovered a potentially active fault at the surface within Hamilton City. Since then Dr Vicki Moon and Dr Willem de Lange have examined the bed of the Waikato River between Cambridge and Taupiri using specialised echo sounders, finding 25 potential fault zones. They believe at least four of those may still be active. Some of the faults could be linked to low grade geothermal activity between Templeview and Orini, and at Horotiu, as well as a patch of basalt volcanoes at Koromatua.
The four identified potentially active faults are: Osborne Rd; Kukutaruhe Fault; and two faults in the Te Tatua o Wairere Fault Zone.
The initial results indicate that the maximum earthquake magnitude for Hamilton remains the same, at 6.8. Dr de Lange says the probability of one occurring also remains at the same low level, but their research indicates it is more likely to be localized. “This means it is less likely to be life threatening, but there could be more shaking and more damage to infrastructure such as sewerage pipes, roads, and other services. That has implications for recovery after a serious event.”
Dr de Lange says the Waikato Expressway has uncovered several fault zones during excavation, and data is also being collected from those sites to better assess the possible magnitude and frequencies of earthquakes near the City.
The research was funded by the EQC, and has been extensively peer reviewed.
Read the full research paper here.