Roman to Middle Age Earthquakes Sourced by the 1980 Irpinia Fault: Historical, Archaeoseismological, and Paleoseismological Hints

The Italian seismic compilations are among the most complete and back-in time extended worldwide, with earthquakes on record even before the Common Era. However, we have surely lost the memory of dozen strong events of the historical period, mostly in the first millennium CE. Given the lack of certain or conclusive written sources, besides paleoseismological investigations, a complementary way to infer the occurrence of lost earthquakes is to cross-check archaeoseismic evidence from ancient settlements. This usually happens by investigating collapses/restorations/reconstructions of buildings, the general re-organization of the urban texture, or even the abrupt abandonment of the settlement. Exceptionally, epigraphs mentioning more or less explicitly the effects of the earthquake strengthened the field working hypothesis. Here, I deal with both paleoseismological clues from the Monte Marzano Fault System (the structure responsible for the catastrophic, Mw 6.9 1980 earthquake) and archaeoseismological evidence of settlements founded in its surroundings to cast light on two poorly known earthquakes that occurred at the onset and at the end of the first millennium CE, likely in 62 and in 989 CE. Both should share the same seismogenic structure and the size of the 1980 event (Mw 6.9).