Newswise — Seismologists with UC San Diego's Scripps Institution of Oceanography are availalbe to discuss the 6.3 seismic event that registered in North Korea and is being reported as due to testing a hydrogen bomb.
Unlike earlier North Korean tests, the waves set off at this explosion were observed at seismic observatories across the whole world including those operated by UC San DIego's IRIS/IDA global network. Our experts say there are several reasons they know this is an explosion rather than a natural earthquake. Yhe explosion originated in a region of North Korea where natural earthquakes rarely occur, and also the depth was zero, whereas many earthquakes originate at many kilometers beneath the earth’s surface.  

The clinching observation is that ratio of the body wave magnitude to surface wave magnitude is large.  In laymen’s terms, we observe waves with greater compressional energy relative to shear energy than would be the case for an earthquake.
The following individuals are available over the weekend to discuss:
Dr. Peter Davis, Executive Director, Project IDA at UC San Diego. Davis manages an international seismographic network with 41 stations in 26 countries worldwide.
Dr. Frank Vernon, Research Geophysicist at the Institute of Geophysics and Planetary Physics at Scripps at UC San Diego. Specializes in earthquake seismology and real-time environmental sensor networks.