Activity

Recent California earthquake with an epicenter at a Navy weapons depot shows tell-tell signs of an underground nuclear weapon discharge. In an natural earthquake, you will find both P and S waves. In this case, the seismograph only shows P-waves.
Several scenarios come to mind but the idea of a nuclear weapon may be a leap and rather, one could say that a very large explosion occurred at the facility. It may or may not be nuclear but simply very large in scale.

https://seismo.berkeley.edu/blog/2009/05/25/of-nuclear-bombs-and-earthquakes.html
https://earthquake.usgs.gov/monitoring/seismograms/75/20190704