The earth beneath our feet is often shifting, sometimes, as today in Italy, with terrible results. Buildings that have stood for hundreds of years can crumble in a minute. When I lived in Oregon, I experienced three quakes that I remember, none catastrophic. Still, I can believe the forecast that the Cascadia fault may produce one that would be.
Earthquakes challenge our basic premise that we can count on the ground beneath our feet. They can force us to wonder what can we truly rely on. At least, that has been the effect they have had on me.