Historically, multiple triggered mainshocks, with time delays of seconds to days, have caused deadly earthquakes along the Italian Apennine belt, a series of central mountain ranges extending the length of Italy. (sciencedaily.com)
California has borne the brunt of several deadly earthquakes, in part because of its famous San Andreas Fault (SAF), where two of the planet's constantly moving tectonic plates move against each other. (discovermagazine.com)