Here I am a the cottage, with an old Linux laptop, and using my phone's Android tethering.
This is right on the cusp of the thrust and shear, and we've had a lot of M4's here. The mechanism is not surprising, it is a mixture of shear and tension. For some reason, the thrust zone has been showing these tension events which indicate a high-angle or rough thrust that doesn't want to let go. You see this in rock testing machines. Once again, the injectors will be laughing, as the pressure should have dropped.
Fairly low intensity, and the earthquake magnitude hasn't been dropped (yet). This will probably start a whole bunch of these again. The mechanism advances when we have a thrust, and we start a new round of high-four earthquakes.