The 30 May 2015 Bonin deep-focus earthquake is the largest ever in the Bonin slab.
The MW 7.9 earthquake was deeper than earlier seismicity by about 100 km.
The location requires strong deformation of the slab, with folding or buckling.
The rupture had radiation efficiency intermediate to great events in 1994 and 2013.
Rupture began with high rupture velocity then expanded with lower rupture velocity.