https://phys.org/news/2018-11-punctuated-earthquakes-madrid-area-uncovers.html

"We know there were also large earthquakes at ~1450 AD and at ~900 AD," says Ryan Gold of the U.S. Geological Survey (USGS), but frequent earthqakes along the fault may not be the norm.

"If earthquakes happen on the Reelfoot fault every 500 years, and have been doing so for hundreds of thousands of years, we would expect to see a mountain range there—but we don't," says Gold. Instead, he suggests the modest fault scarp associated with the Reelfoot fault indicate that the earthquakes haven't been sustained over a long period of time.