The 1706 Abruzzo earthquake, also known as the Maiella earthquake, occurred on November 3 at 13:00 CEST. The earthquake with a possible epicenter in the Central Apennine Mountains (Maiella), Abruzzo had an estimated moment magnitude of 6.6–6.84 Mw .[1] It was assigned a maximum Mercalli intensity of XI (Extreme),[1] causing tremendous destruction in Valle Peligna. At least 2,400 people were killed.[2][3]
In the Central Apennines, the zone of extension is about 30 km wide, closely matching the zone of observed extensional strain as shown by GPS measurements. Recent large earthquakes in this area have been caused by movement on southwest-dipping normal faults.[4] The region has seen very destructive earthquakes in its history, including an Mw 6.6 in the 2nd century AD, 1706, 1915, 1933, and 2009.[6]
Earthquake
The earthquake was associated with shallow crustal faulting within the extensional zone on the Italian Peninsula, near Maiellamassif. This part of the tectonic zone represents the outermost anticline of the Central Apennines fold and thrust belt. Thrusting resulted in uplift and formation of the massif until the late Pliocene, when extension became dominant. The Caramanico Fault, a 30-km-long normal fault, runs the western base of the massif. Two other faults; the Palena and Porrara faults are situated at the southwestern part of the massif.[7]
The source mechanism of faulting is debated between normal or thrust faulting. A known fault commonly associated with the earthquake is the Porrara Fault; a 20-km-long, west northwest–east southeast trending normal fault located at the southwestern portion of Maiellamassif (Monte Porrara). The fault scarp associated with the Porrara Fault is visible for 3 km.[7] However, modelling of the earthquake using its geological and seismic intensity information suggest rupture on a southwest dipping thrust fault at a shallow depth of 5–10 km.[8]
Damage
The 1706 disaster occurred just three years after a series of destructive earthquakes struck the Central Apennines. It lasted twenty seconds but caused massive destruction.[9] A second shock on the night of November 4 caused additional damage and some casualties in areas less affected by the previous one. In total, the earthquakes killed 2,400 people.[10]
Damage was also reported in the regions of Lazio, Molise, and Apulia. In Cassino and Sora, Lazio, and the wider Apulian region, plaster on buildings fell. It also fell off the Monte Cassino abbey. Many towns in Molise suffered minor to extensive damage, but no human casualties were reported.[14]
^National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information (1972), Significant Earthquake Information, NOAA National Centers for Environmental Information, doi:10.7289/V5TD9V7K