Superquake

In January 1973, Newsweek magazine reported an earthquake somewhere in the world , and added: "It was not a superquake as earth tremors go."

Source: wiktionary

Others have suggested that, since this creeping section separates the two segments that have produced great earthquakes, that it is unlikely a "superquake" that ruptured all three sections could occur at one time.

Source: wiktionary

This "superquake" may have been the largest in a series of earthquakes, thus marking the end of what's known as a supercycle: a sequence of several large earthquakes.

Source: wiktionary