Contrary to worldwide news reports, the earthquake on Sunday (20 May 2012) centered in the Italian region Emilia-Romagna about 40 km. north of the city of Bologna was not what it's being described in every news report I can locate – not "...a first for the region in centuries."
Nor should it have been "fairly surprising to seismologists."
Ninety-two years ago, on September 8-9, 1920, the New York Times reported "500 DIE IN ITALY, 20,000 HOMELESS AS QUAKES RECUR"... The paper reported the series of earthquakes took place in "The Emilia district... the communities suffering most today were Reggio, Ospedaletti, Bussana, Toano, and Cavola."
The article explained, "The Emilia embraces the district between the Apennines and the River Po and is dived into the eight provinces of Piacenza, Parka, Reggio, Modena, Bologna, Ferara, Ravenna and Forli. It covers an area of some 7,920 square miles and has a population of approxmately 2,500,000 persons."
So why are contemporary reporters in 2012, reporting the new quakes in the same region saying things such as:
"The strong quake rocked an area with a long history of earthquakes, yet one that has kept relatively quiet for hundreds of years."
"'There has not been a whole lot of action in that area,' Caruso said. 'The fact that they do have records of earthquakes going back a couple thousand years shows this area hasn't been seismically active for a long time,' he said.
"Part of the problem is that the region around the epicenter of the quake (between the cities of Modena and Ferrara) is not as accustomed to earthquakes as in other parts of Italy, such as the North-East, Sicily, or the Apennine region (where l'Aquila is located). Until 2003, it was not even included in seismic hazard maps. 'The buildings which collapsed were mostly built before then, with no antiseismic measures at all,' says Calvi. 'In such cases, prefabricated buildings such as sheds and supermarkets are more at risk than houses, because of their weak structure.'
"In 2003, though, seismologists introduced a new map of seismic hazard across Italy, and the area of Sunday's earthquake was reclassified as one of medium risk. 'We were estimating a 10 per cent probability of an earthquake of this kind in that area over the next 450 years,' says Gianluca Valensise, a research director at INGV. 'This earthquake was a rare event, but not a surprising one.'"
Even Italian reports don't mention the shock of 1920. For example:
"Per quanto riguarda gli altri terremoti che possiamo considerare 'grandi' in Italia, quello del 1976 in Friuli e' stato di magnitudo 6.2, quello dell'Irpinia (1980) di magnitudo 6.8, quello di Umbria e Marche (1997) di magnitudo 5.6." (Regarding the other earthquakes that we consider 'big' in Italy, that of 1976 in Friuli , and was magnitude 6.2, the Irpinia (1980) with a magnitude of 6.8, that of Umbria and Marche (1997) with a magnitude of 5.6.)
It's as if the earthquake and aftershocks of 1920 in this part of Italy never happened!