Yes, this is interesting.
Good catch, why would you be monitoring the sites?
Went to ATS, saw the headline, and clicked the link. Pretty obvious. Same signature worldwide.
You don’t see it on a few stations, but that is not unusual. I sometimes watch the stations around Mt. Rainier, and often something shows as a somewhat significant event on one station and doesn’t even show at all on others. I guess the waveform can echo and bounce around and even cancel itself out sometimes.