The seismic activity has already increased very much in the recent few months, think of the Croatian, the Japanese etc. earthquakes, Mount Etna's eruption and so on. Here's a seismic map: http://ds.iris.edu/seismon/index.phtml
You may ask, how did ancient people know about the future? They didn't, only these things repeat periodically, just like everything else. When a population gets big enough, the evil part tries to take power, and then natural catastrophes eliminate most of the population.
"Further statistical investigations of the results based on cumulative storm hours show consistency with those based on storm days, suggesting that the high probability of geomagnetic storms prior to large-mega earthquakes is significant and robust." Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712061/