A serendipitous note discovered in a 15th-century Hebrew prayer book has filled an important gap in Italy's earthquake history, providing a brief glimpse into a previously unknown earthquake that affected the Marche region in the central Apennine peninsula.
Paolo Galli discovered the note while searching for contemporaneous records of another historic Italian earthquake in the Vatican Apostolic Library. He wrote in Seismological Research Letters that the note "not only helps us partially fill the gap in the history of Italian earthquakes, but also prompts us to reflect on the fact that even in the era of written records, we still know nothing about the occurrence of earthquakes."
The Importance of Historical Data in Earthquake Research
"Italy's historical data are undoubtedly the richest, but there are gaps in time and place," Galli said. "For example, unlike the Kingdom of Naples, the Papal States (the Marche region was part of the Papal States in the 15th century) are certainly less well-documented in relation to earthquakes."
The note discovered by Galli was written on the leaves of a prayer book that had been copied in Camerino in Marche and completed in September-October 1446. Eight lines of text on the note describe the earthquake that struck around Camerino, which destroyed houses and the governor's courtyard, and devastated cities and villages, "which have been reduced to heaps of stones."
"In Camerino, men and women dressed in white pastel dresses, leading horses, mules and donkeys, laden with bread, food and wine, come here in order to hold the hands of the poor," the note read, while also noting that earthquakes in the area lasted from March to September.
This note is currently the only evidence of a devastating earthquake in the Marche region in the 15th century. Galli said a 1446 petition in Petrino, 20 kilometers from Camerino, requesting funds to repair the walls and castle may be the only written evidence of a damaging earthquake in the area.
A rare glimpse of seismic activity in the 15th century
There are only 450 well-documented earthquake observation points in Italy in the 15th century, about half of which come from an important historical earthquake in the central and southern Apennine Peninsula in 1456. Galli had been looking through the library's medieval manuscripts, hoping to find out more about the series of earthquakes, when he came across the prayer book.
He explains: "The earthquake of 1456, or rather the earthquake of 1456, represents the most catastrophic sequence of earthquakes that occurred in south-central Italy in the late Middle Ages. Despite a large amount of historical data, especially a special treatise on the earthquake written by the famous humanist Giannozzo Manetti, we were still unable to determine the different epicenter areas and therefore the parameters of the individual mainshocks - their magnitude and epicenter - and their origins."
Ghali said the damage described in the prayer book's instructions suggested that Camerino may have experienced strong shaking, with a magnitude of about 8 on the Mekali-Kankani-Siberg seismic intensity scale. This level meant that half of the town's buildings were severely damaged and partially collapsed, along with columns, monuments and walls.
Galli said that the Camerino earthquake may be the "twin brother" of the 1799 earthquake in the area, when the 6.2-magnitude earthquake also caused similar strong shaking: "Of course, this is only a hypothesis, but by comparing the epicenter area and the extent of damage in Camerino and its surrounding areas, it is possible that the earthquake effects described in our manuscript are similar to the 1799 earthquake, albeit only briefly described."
He added: "In particular, the manuscript mentions that many settlements around Camerino were reduced to cairns, suggesting that the epicenter area may have been the same as in 1799. Likewise, the lack of far-field information suggests that the earthquake was most likely caused by a shallow fault, which may have been the case in 1799."
Compiled source: ScitechDaily