[Island Chris]

The M7.4 was in the last hour and no focal mechanism posted. Offshore Russia

https://earthquake.usgs.gov/earthquakes/...#executive

[Island Chris]

Now is M7.7 and is strike-slip

[Island Chris]

The quakes seem to be strung out parallel to the trench. The SE-striking nodal plane of the M7.7 is right-lateral. I recall that subduction in that corner of the Pacific Plate is highly oblique, and the strike-slip component would be right-lateral. The oblique slip "partitions" into thrust on the subduction zone and right-lateral above it.

Seems like Plate Tectonics and structural geology work.

[Island Chris]

There is now a summary at the link:

https://earthquake.usgs.gov/earthquakes/...#executive

Similar to what I wrote except they say the right-lateral quake is on the plate boundary, implying no subduction. Not sure of they are correct; there seems to be a trench. I suppose a slab may be imaged or not imaged and it is known if there is subduction, so I could be wrong and USGS could be correct. But remember 2004 Indonesia: the northern part of that rupture is highly oblique plate motion yet it still had a subduction quake. I recall that most seismologists thought it could not have a Great subduction quake in the north.

Chris