By Lamont-Doherty Earth Observatory of Columbia University Mellon Professor of Natural Sciences Emeritus Paul Richards
- This was an explosion and not an earthquake;
- It was roughly five times bigger than North Korea's first nuclear test (on Oct. 9, 2006);
- Because it was so large (the equivalent of thousands of tons of TNT, or several kilotons), it is not credible for it to have been a chemical explosion. It must have been nuclear;
- The seismic stations that monitor that part of the world are of such high quality, that explosions can be detected and identified even down to a few percent of a kiloton.
This all goes to show that expanded seismic networks have made it possible to quickly detect and assess even small nuclear tests.