Abstract
We document the paleoseismology of the Long Valley Fault, Central Otago, New Zealand. A single trench excavated across the 21 km long, northeast-striking reverse fault reveals evidence for three ground-rupturing earthquakes. Optically Stimulated Luminescence dates (including OxCal analysis) of displaced sedimentary units are used to constrain the timings of these events. The antepenultimate event is constrained at 74.4 ka (81.4–67.6 ka, 95% confidence interval), the penultimate event at 37.4 (55.2–19.1) ka, and the most recent event at 10.5 (14.3–6.7) ka. These events show a total of 5 ± 0.2 m of dip slip in the trench, with a range of 1–2 m displacement per event. The estimated magnitude and mean recurrence interval for the Long Valley Fault are Mw 6.9 - 7.0 and 32.0 ± 12.3 kyrs, respectively. The study contributes to the growing Otago paleoseismic database, which will eventually be used to understand regional space–time deformation behaviours in transpressional tectonic environments.