In the April 18th Weekly Geopolitical News and Analysis, I reported that seismographic evidence from the April 16th earthquake in Southern Japan showed it was a natural earthquake. That was wrong. Below is the seismographic evidence from the National Research Institute for Earth Science and Disaster Prevention.
It shows very clearly that the earthquake has the signature of an underground nuclear explosion and not a natural earthquake.
See here for a contrast between a natural earthquake and a nuclear explosion: