Gravity interpretation profile across Hikurangi subduction zone using seismic constraints — Hawke's Bay to Hikurangi Trench

Abstract

Constraints are placed on crustal structure between Hawke's Bay and the Hikurangi Trench, Hikurangi subduction zone using seismic, microseismic and gravity data. Seismic refraction and exploration well data indicate a thickness of 5.5 kilometres for sediments beneath Hawke's Bay overlying the large negative gravity anomaly in that region, these sediments contributing about -550 μN/kg to that anomaly. Modelling carried out using these data and new microseismic information on the geometry of the subducted Pacific plate indicate that the large negative gravity anomaly results largely from the combined effect of subducted oceanic crust, low density Tertiary-Quaternary age surface sediments, and possible downward flexure of the overlying crust.

Keywords:

• Gravity
• seismic
• subducted crust
• subduction zone