The M6.7 and the 6.4 (news) or 6.1 (USGS) aftershock both have focal mechanisms: either rather flat NE-dipping thrust, or very steep reverse. Being close to the subduction zone, the NE-dipping thrust is more likely. This subduction zone had a M8 about 2000 years ago....I'd have to dig in my references or notes to find details of subduction quakes here.
Chris