One of the feeds I subscribe to is the USGS Earthquake Center ShakeMaps. You can see it in my blogroll under the "Nature" category in the sidebar.
When I heard the reports this morning that North Korea had tested a thermonuclear "device", I checked the feed. Sure enough, there it was:
Note the time, depth and magnitude. These all correspond to what's being reported. The magnitude is 4.2 here, instead of the 3.6 that's being widely reported, but it's close enough. I haven't seen any strong surface earthquakes of natural origins.
While the event chills me, I take hope in the abilities we have for monitoring and communicating the planet and the violence we do to it and ourselves. With feedback comes learning, from learning, knowledge, from knowledge - if we live long enough - wisdom.