The 2nd Century AD earthquake in Central Italy:a Tentative Parameterization from the Available Archaeosismological Data

Abstract

The 2nd century AD earthquake in central Italy is only known by an epigraph that mentions restorations at the ancient locality of Pagus Interpromium. The available seismic catalogues report this event with the conventional date of 101 AD, a magnitude Maw of 6.3, and an epicentral location at the village of San Valentino in Abruzzo Citeriore in the province of Pescara. Starting from this sparse information, we gathered all the archaeological data collected during modern excavations at sites which were presumably struck by the earthquake, to improve our knowledge of the damage pattern. The most recent archaeological material found in a collapsed unit is a coin of Antoninus Pius, dated at 147-148 AD. This may represent a post quem date very close to the occurrence of the earthquake. The gathered information has allowed us to roughly delineate an area of possible damage, including the Sulmona Plain and surrounding areas. Comparisons between the possible 2nd century damage distribution and (i) the damage patterns of more recent historical events that have struck the investigated area, (ii) a simulated distribution of intensity, given a certain epicentre (i.e. the Sulmona area) and a related epicentral intensity and (iii) a shaking scenario obtained by assuming the activation of the major active fault of the Sulmona Plain area (the Mt. Morrone fault, Mw 6.6-6.7 based on the fault length), have revealed consistency between the ancient earthquake and the activation of this fault. The comparison between the presumed 2nd century damage and the shaking scenario suggests that also the magnitude mentioned is consistent with the presumed effects of the ancient earthquake. Therefore, we can conclude that: (i) the earthquake occurred shortly after 147-148 AD; (ii) a magnitude Mw 6.6-6.7 can be attributed to it; and (iii) the probable macroseismic epicentral area was Sulmona.