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+--- Thread: M6.2 followed by M7.4 Aleaitian trench (/showthread.php?tid=752)
M6.2 followed by M7.4 Aleaitian trench - Island Chris - 07-18-2017
The M7.4 was in the last hour and no focal mechanism posted. Offshore Russia
https://earthquake.usgs.gov/earthquakes/eventpage/us20009x42#executive
RE: M6.2 followed by M7.4 Aleaitian trench - Island Chris - 07-18-2017
Now is M7.7 and is strike-slip
RE: M6.2 followed by M7.4 Aleaitian trench - Island Chris - 07-18-2017
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.
RE: M6.2 followed by M7.4 Aleaitian trench - Island Chris - 07-18-2017
There is now a summary at the link:
https://earthquake.usgs.gov/earthquakes/eventpage/us20009x42#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