Evidence of Seismic Slip on a Large Splay Fault in the Hikurangi Subduction Zone

The Hikurangi subduction zone is capable of producing moderate to large earthquakes as well regularly repeating slow slip events. However, it unclear what structures host these different styles along the margin. Here we address whether splay faults can seismic at shallow (<1 km) depth by investigating P?paku fault, sampled during International Ocean Discovery Program Expedition 375. We use biomarker thermal maturity search for evidence frictional heating within turbiditic sediments fault. Four zones localized high temperature are found near top fault zone, which interpreted be slip. Thermal modeling shows that most likely maximum displacement on each event was 14–17 m. Our results demonstrate and potentially other margin, coseismic have potential produce tsunami (e.g., runup heights >1 m observed in 1947 Poverty Tolaga Bay earthquakes.