Never underestimate the effects of small arms in determined hands, Anon.
https://en.wikipedia.org/wiki/11_November_2018_Mayotte_seismic_event
https://bigthink.com/hard-science/mystery-seismic-wave/
https://spacefed.com/other/unusual-seismic-phenomenon-heard-around-the-world/
https://www.nationalgeographic.com/science/article/strange-earthquake-waves-rippled-around-world-earth-geology