This is hilarious. Texas Permian frack oil is $2 a barrel, provided they can dump the freshwater frack waste for nearly free. And we know that is crack cocaine for earthquakes. So they keep going somewhere new and start injecting. Today it's Houston. The Illinois one is natural, but the same mechanism. My treatment solution might knock it up to $3, maybe.
ps. Texas is very sensitive to this now, so there might only be the one quake.