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Publications: SRL: Opinion |
November/December 2009
Earthquake Casualties in Italy: The Blame Game
This note focuses on the true and perceived responsibilities for the recent earthquake losses in central Italy and on the status of seismic zoning in our country.
The 6 April 2009, Mw 6.3 earthquake near L’Aquila (central Italy) was a standard Apenninic event: its magnitude, depth, and focal mechanism are consistent with the seismotectonic features of the area; historical earthquakes occurred in the same area with comparable characteristics, including a long-lasting sequence of foreshocks and aftershocks; strong ground motions seem to match well with existing predictive relationships; and the seismic hazard reaches the highest levels for Italy both on conventional and on time-dependent probabilistic maps. Despite the fact that a seismic building code was adopted in this area as early as 1927, the unacceptable death toll of the earthquake (around 300 victims) is largely to be blamed on the poor quality of construction. As with past earthquakes, severe damage and collapse mainly affected old buildings (unreinforced masonry or stone buildings); but surprisingly, a number of multistory buildings of relatively new construction (reinforced concrete frame buildings with brick infill) were destroyed too: among these, L’Aquila’s main hospital (finished in 2000) and the university’s dormitory (built in the late 1970s).
The responsibility for these collapses is clearly due to the lack of seismic-resistant building elements, but the Italian media obscured this by starting a sort of “blame game.” Eager for sensational news, they first devoted their attention to a prediction reportedly obtained using radon measurements by a technician of an astrophysics research institution. The first targets of the blame game were the authorities and seismologists guilty of not listening to this man. It did not matter that his data were not available for review, nor that his prediction was made for March 29, in Sulmona: eight days and 60 km away from the actual epicenter.
As with past earthquakes, severe damage and collapse mainly affected old buildings (unreinforced masonry or stone buildings); but surprisingly, a number of multistory buildings of relatively new construction (reinforced concrete frame buildings with brick infill) were destroyed too: among these, L’Aquila’s main hospital (finished in 2000) and the university’s dormitory (built in the late 1970s).
Several days after the earthquake, journalists “discovered” the regional seismic zoning map, showing that under the current building code L’Aquila and surrounding towns are assigned to zone 2 (on a scale where zone 1 is the highest seismic hazard and 4 is the lowest). In fact, the town of L’Aquila was first designated “seismic” after the 1915 Fucino earthquake and has been assigned to zone 2 since 1927. They also “discovered” that according to the most recent seismic hazard map, the damaged area could have been assigned to zone 1. A new target for the blame game! Unfortunately, Italian journalists do not like to report that the new provisions apply only to new construction and that the difference between zone 1 and 2 is not substantial. Of course, the almost erratic evolution of the Italian seismic zoning and its inherent complexity make it difficult to explain its function to non-experts (and experts alike!). The following is our attempt to draft a history of how the seismic zoning of Italy has come together.
The history of seismic zones in Italy follows the occurrence of major earthquakes: after the event, the affected area is officially designated “seismic” and some sort of seismic design is required. After the 1980 Irpinia and Basilicata (southern Italy) earthquake, the first comprehensive seismic zoning map was approved for use in 1984. It divided 3,000 municipalities (out of approximately 8,000) into three zones. The remaining municipalities were considered subject only to minor earthquakes and small ground motion, so they were not subjected to any seismic provision. An update of the 1984 map was proposed in 1998 using a modern PSHA study, but the authorities simply ignored it.
Earthquake preparedness and risk mitigation reappeared on political agendas and on the news only after the 2002 earthquake (Mw 5.7) near San Giuliano di Puglia (southern Italy). This village was left out of the 1984 zoning but should have been assigned to seismic zone 2 according to the 1998 update. The Italian government acted swiftly: in six months a new seismic building code was adopted and the seismic zoning was updated based on the 1998 map. A fourth zone was created to make sure that all the territory is assigned to one seismic zone, thus acknowledging that some kind of seismic design is needed everywhere to reduce the impact of earthquakes. It looked like the beginning of a new, modern era: some regional authorities even began checking their schools and public buildings. Unfortunately it did not last long: as soon as the excitement passed, the need for “less emotional” provisions took over and the enforcement of the new provisions was delayed. Meanwhile the Istituto Nazionale di Geofisica e Vulcanologia (INGV) prepared the new, updated seismic hazard map (aka MPS04). The map was officially adopted as the reference that regional authorities must use to update their seismic zoning maps. Once again, it looked good, except that it was not made mandatory for the regional authorities to update their seismic zoning.
Unfortunately, Italian journalists do not like to report that the new provisions apply only to new construction and that the difference between zone 1 and 2 is not substantial.
The media’s attention is now focused on the reconstruction, and MPS04 is very popular; its official website (http://zonesismiche.mi.ingv.it, in Italian) has received an unexpected number of hits and is linked to by several forums, blogs, and other websites. The interest seems to be on the Abruzzo region only with little or no attention paid to the rest of the country, where a huge deficit of seismic design has accumulated through the years (e.g., Catania: destroyed by the 1693 earthquake, but not included in any seismic zone until 1984).
From our point of view, the situation of the municipalities where seismic provisions were adopted only recently is alarming. In these areas most if not all buildings are constructed without any kind of seismic design. Whether it is the seismologist’s job to educate the population about earthquake safety or somebody else’s (e.g., communication experts, authorities), it is clear that preparedness and prevention are the best means to reduce the impact of earthquakes. In Italy this message does not seem to suit any TV or newsroom format, so it does not reach the population at risk. While preparing MPS04 we were guided by the belief that our expertise and our knowledge were serving the common good; far from the intention of generating panic or fear, we wish to remind all Italians that our country is most certainly seismically active, and that prevention and earthquake preparedness are keys to building a safe environment. 
Note: The opinions expressed in this article are those of the authors and not of their employers.
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Posted: 20 October 2009