Late Holocene earthquakes on the Papatea Fault and its role in past earthquake cycles, Marlborough, New Zealand

ABSTRACT

The north-striking sinistral reverse Papatea Fault ruptured with a very large (up to 12 m) oblique slip as part of the 2016 M_W 7.8 Kaikōura earthquake in the northeastern South Island. Paleoseismic studies were undertaken at three sites along the Papatea Fault, named Murray’s roadcut, Jacqui’s Gully (both on the main strand), and Wharekiri trench (western strand). These sites provide evidence for up to three Late Holocene paleoearthquakes prior to 2016 (=E₀) on this previously unmapped active fault, with preferred OxCal-modelled timings of 98–149 (E₁), 546–645 cal yr BP (E₂), and >738 cal yr BP (E₃). Event correlations between the sites are generally consistent across these past events, implying that the two strands of the Papatea Fault link at depth and rupture together co-seismically as in 2016. Comparisons of its paleoseismic record with the Kekerengu Fault and uplift data from Waipapa Bay and Kaikōura, suggest that the Papatea Fault may have three distinct rupture modes: (i) Kaikōura-type multi-fault ruptures with multi-metre, anelastic block displacements and associated major landscape change; (ii) multi-fault earthquake ruptures with other regional fault combinations; and (iii) single-fault Papatea ruptures with metre-scale displacement. OxCal models offer the possibility that the E₁ fault rupture occurred in 1855 CE.

KEYWORDS:

• Papatea Fault
• 2016 Kaikōura earthquake
• Waiau Toa/Clarence River
• paleoseismicity
• fault behaviour

Acknowledgments

The authors wish to acknowledge the mana whenua of Ngāi Tahu and Ngāti Kuri in the Waiau Toa/Clarence valley. Warm thanks to the Murray, King, and Hamilton families who were always helpful and allowed us to undertake paleoseismic studies on their land. We acknowledge Andy Nicol, Lisa Dowling, Ian Hamling, Ed Nissen, Anna Diederichs, Ryosuke Ando, and Elyse Gaudreau for their help in the field. We thank the Rafter Radiocarbon (Margaret Norris, Jenny Dahl) and the UCLA Luminescence (Nathan Brown, Sourav Saha, Seulgi Moon) laboratories for dating and advice around our results. Genevieve Coffey provided early review comments on this manuscript. Jonathan Griffin and another reviewer helped to significantly improve the final version of this paper. Thanks also to the editor (Andy Nicol) and journal staff for advice toward the final product.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

AMS radiocarbon dates were analysed at the Rafter Radiocarbon Laboratory, Lower Hutt. Radiocarbon dates are modelled in OxCal 4.4.4 using the Southern Hemisphere 2020 calibration dataset (Hogg et al. 2020). Infra-red stimulated luminescence dates were analysed at the UCLA Luminescence Laboratory, Los Angeles, California. The remainder of the datasets used to come from published sources listed in the references.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

Funding was provided through a Natural Hazards Research Platform [grant number 2017-GNS-01-NHRP] to RML and GNS Science MBIE Strategic Science Investment Funding [grant number C05X1702].