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Paleoseismic trenches excavated at two sites reveal ages of late Holocene earthquakes along the Conway segment of the Hope fault, the fastest‐slipping fault within the Marlborough fault system in northern South Island, New Zealand. At the Green Burn East (GBE) site, a fault‐perpendicular trench exposed gravel colluvial wedges, fissure fills, and upward fault terminations associated with five paleo‐surface ruptures. Radiocarbon age constraints indicate that these five earthquakes occurred after 36 B.C.E., with the four most recent surface ruptures occurring during a relatively brief period (550 yr) between about 1290 C.E. and the beginning of the historical earthquake record about 1840 C.E. Additional trenches at the Green Burn West (GBW) site 1.4 km west of GBE reveal four likely coseismically generated landslides that occurred at approximately the same times as the four most recent GBE paleoearthquakes, independently overlapping with age ranges of events GB1, GB2, and GB3 from GBE. Combining age constraints from both trench sites indicates that the most recent event (GB1) occurred between 1731 and 1840 C.E., the penultimate event GB2 occurred between 1657 and 1797 C.E., GB3 occurred between 1495 and 1611 C.E., GB4 occurred between 1290 and 1420 C.E., and GB5 occurred between 36 B.C.E. and 1275 C.E. These new data facilitate comparisons with similar paleoearthquake records from other faults within the Alpine-Hope-Jordan-Kekerengu-Needles-Wairarapa (Al-Hp-JKN-Wr) fault system of throughgoing, fast-slip-rate (⁠≥10  mm/yr⁠) reverse-dextral faults that accommodate a majority of Pacific-Australia relative plate boundary motion. These comparisons indicate that combinations of the faults of the Al-Hp-JKN-Wr system may commonly rupture within relatively brief, ≤100-year-long sequences, but that full "wall-to-wall" rupture sequences involving all faults in the system are rare over the span of our paleoearthquake data. Rather, the data suggest that the Al-Hp-JKN-Wr system may commonly rupture in subsequences that do not involve the entire system, and potentially, at least sometimes, in isolated events. [ABSTRACT FROM AUTHOR]

Coseismic rupture of the 19-km-long north-striking and west-dipping sinistral reverse Papatea fault and nearby structures and uplift/translation of the Papatea block are two of the exceptional components of the 14 November 2016 Mw 7.8 Kaikōura earthquake. The dual-stranded Papatea fault, comprising main (sinistral reverse) and western (dip-slip) strands, ruptured onshore and offshore from south of Waipapa Bay to George Stream in the north, bounding the eastern side of the Papatea block. Fault rupture mapping was aided by the acquisition of multibeam bathymetry, light detection and ranging (lidar) topography and other imagery, as well as differential lidar (D-lidar) from along the coast and Clarence River valley. On land, vertical throw and sinistral offset on the Papatea fault was assessed across an aperture of ±100 m using uncorrected D-lidar and field data to develop preliminary slip distributions. The maximum up-to-the-west throw on the main strand is ~9.5±0.5 m, and the mean throw across the Papatea fault is ~4.5±0.3 m. The maximum sinistral offset, measured near the coast on the main strand, is ~6.1±0.5 m. From these data, and considering fault dip, we calculate a maximum net slip of 11.5±2 m and an average net slip of 6.4±0.2 m for the Papatea fault surface rupture in 2016. Large sinistral reverse displacement on the Papatea fault is consistent with uplift and southward escape of the Papatea block as observed from Interferometric Synthetic Aperture Radar (InSAR) and optical image correlation datasets. The throw and net slip are exceedingly high for the length of the Papatea fault; such large movements likely only occur during multifault Kaikōura-type earthquakes that conceivably have recurrence times of ≥5000-12,000 yrs. The role of the Papatea fault in the Kaikōura earthquake has significant implications for characterizing complex fault sources in seismic hazard models. [ABSTRACT FROM AUTHOR]