This was a magnitude Mw 7.7 earthquake with epicenter located in the Pacific Ocean at about 180 km east of Hachinohe, Aomori (haruka-oki means "far offshore").

The convergence rate across this boundary lies in the range of 7.9–9.2 cm per year.

[7] The plate interface in the area of the earthquake epicenter shows an abrupt increase in dip from about 5° to about 15°, 80 km landward of the Japan Trench.

According to the studies of past great earthquakes, a weak seismic coupling is suggested in the offshore Sanriku region.

[10] From the distribution of past seismicity, the width of coupling at 40°N was assumed to be about 150 km.

[11] This was an interplate earthquake,[12] with a low-angle reverse fault focal mechanism, which ruptured part of the plate interface.

The second phase migrated significantly further down-dip and to the south, along the plate boundary.

[7] The main event released a seismic moment of about 3×1020 Nm, corresponding to magnitude Mw  7.59.

Most of the aftershocks occurred in the region of small slip in the main rupture.