Earthquake and Tsunami Potential of the Hikurangi Subduction Thrust, New Zealand: Insights from Paleoseismology, Gps, and Tsunami Modeling

Wallace, L.; Cochran, U.; Power, W.; Clark, K.

Oceanography 27(2): 104-117


ISSN/ISBN: 1042-8275
DOI: 10.5670/oceanog.2014.46
Accession: 068510266

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The Hikurangi subduction margin, where the Pacific Plate subducts beneath the North Island of New Zealand, poses a major seismic and tsunami hazard to the New Zealand region, but its seismic and tsunami potential is largely unknown because of New Zealand's short (< 170 years) historical record of seismicity. This article discusses the implications of results from GPS, paleoseismology, and tsunami modeling studies for understanding Hikurangi subduction earthquake and tsunami potential. Paleoseismic and geodetic data indicate that earthquakes of Mw 8.0 and larger are certainly plausible at the Hikurangi margin. Paleoseismic evidence for large megathrust earthquakes beneath Hawke Bay in central Hikurangi demonstrates that large seismic slip may occur within an area that currently slips in episodic slow slip events. This result has important implications for seismic hazards at subduction margins elsewhere. Strong similarities between the subduction zones of the Hikurangi margin and the Japan Trench suggest that a giant Mw 9.0 earthquake similar to the 2011 Tōhoku-Oki earthquake may be possible for the Hikurangi margin. Such an event would generate a large tsunami that would inundate much of the east coast of the North Island. Understanding of the earthquake potential of the Hikurangi megathrust is only in its infancy, and we recommend a number of studies to increase knowledge.