The Hikurangi Subduction Zone in New Zealand can produce very large megathrust earthquakes similar to the 2004 Sumatra Mw9.2, 2010 Maule Mw8.8, and 2011 Tohoku Mw9.0 earthquakes. Although the associated ground motions would pose significant seismic hazard to much of New Zealand, the last known large earthquake of this type in New Zealand occurred around 1855 and therefore no observed ground-motion records are available. In this study, we present progress towards simulation of realistic ground motions from megathrust earthquakes along the Hikurangi Subduction Zone using physics-based hybrid broadband ground-motion simulation. Although ground-motion simulations have been previously performed for megathrust earthquakes on the Hikurangi Subduction Zone, this study is the first to incorporate simulation models validated using observed ground motions from subduction interface earthquakes in New Zealand. Ground-motion simulations will be conducted for probable scenarios to produce a distribution of ground-motion estimates of various intensity metrics for locations throughout New Zealand. Ground-motion sensitivity to rupture characteristics such as hypocentre location, subevent location, rupture velocity, and variation of subfault slip will be investigated and quantified. It is hoped that the interface-specific simulated waveforms and estimated ground-motion intensities will be useful for seismic hazard analysis, risk mitigation, and disaster preparedness.