Other forms: seismically
For the ancient Greeks, "seismos" meant an earthquake. Later on, when the study of earthquakes became a science, anything seismic meant anything related to the study of the pressures in the Earth's crust.
The English language has a long and proud tradition of stealing scientific words and applying them in all sorts of ways that scientists probably wish they didn't: Darwinian, tempestuous, evolutionary — to name but three. It's the same with seismic, which is now far more likely to be applied to political or psychological turmoil than anything to do with the earth opening up and molten hot lava spewing out.