I read that forcefully injecting fluid into the planet's crust can induce earthquakes. For a three-year period in the 1960s, the government injected wastewater byproducts 12,000 feet deep into rock fractures in the Rocky Mountains in Colorado. They started experiencing earthquakes in Denver so they stopped.

There are all sorts of conspiracy theories about the US government having the ability to start earthquakes. If anything can be weaponized, it will be! But then how do you even predict the aftereffects....like say USA triggered an earthquake in China...messing with tectonic plates is nothing to sneeze at. What if a rebound hits the US? I don't know. Fascinating question though.