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Modenesi's Tower in Finale Emilia was destroyed by a magnitude 6.0 earthquake that hit Emilia on May 20, 2012, killing 7 people and destroying many historic buildings. Credit: Roberto Serra/Iguana Press/Getty Images News.

The tortuous path of the new Italian seismic hazard map has hit another roadblock. Nature Italy has learned that the National Institute of Geophysics and Vulcanology (INGV) has completed the internal evaluation of the map, and that the outcome was negative. This means the new map has effectively been rejected by the same institute whose scientists have worked on it for more than seven years. INGV was tasked in 2015 by the Civil Protection to develop a new map that would update the 2004 one, on which Italian anti-seismic building requirements are based. The evaluation procedure is required for all INGV products that have a regulatory impact.

“The decision was based on the opinion of 13 international peer-reviewers, five selected by the INGV scientific council and the rest by myself”, says INGV president, Carlo Doglioni. “They were asked if the model is scientifically sound and suitable to inform the building code, and their overall assessment was negative,” Doglioni adds. The decision came in December, but it has not been made public so far.

In principle, the Civil Protection could decide to use the map for amending building codes anyway. Its own scientific advisory body, the Major Risk Commission, had approved it in February 2022, after requesting substantial changes to the initial version prepared in 2019. But the Civil Protection says it will continue working with INGV to get to a map approved by both parties. “The dialogue with the Institute and the entire scientific community is ongoing,” the Civil Protection press office wrote to Nature Italy. “We aim at approving a model with the broadest scientific support”.

Doglioni is not surprised by the outcome of the evaluation procedure. “There are many scientists who criticize the approach taken by the coordinators of the map, the so-called Probabilistic Seismic Hazard Assessment, because it relies primarily on historical data and neglects geological, geodetic and rheological information”.

The two coordinators of the map, Carlo Meletti, a researcher at INGV, and Warner Marzocchi, professor at the University of Naples Federico II, note that their work did include different approaches. “When we started the work on the new map in 2015, we opened a call to the Italian seismological community to gather as many models as possible”, Meletti says. “No approach was disregarded on ideological grounds, and we also included models based mostly on geological information rather than historical data. In the end we received 25 proposals from 150 researchers.”

The two scientists also think that the picture painted by the referees’ opinions is more nuanced, at least for those selected by the scientific council. In addition to the final version of the map, delivered to the Civil Protection at the end of 2021 and called MPS19.s, the referees also evaluated the initial version, called MPS19, that was delivered in 20191. MPS19.s was developed to accommodate some requirements from the Major Risk Commission, in particular the request to reassess hazard levels in the southern Italian regions by giving a different weight to historical data.

“Only one referee criticized the probabilistic approach, while the remaining four stated that the original model, MPS19, was scientifically sound and sufficiently validated by the available data.” Meletti says. “However, two among them were dubious about the changes introduced in MPS19.s”.

In the letter addressed to the board of directors to inform them about the outcome of the evaluation, the INGV scientific council stated that even if the referees have pointed out that MPS19.s has limitations, the original model on which it is based, MPS19, is state-of-the-art.

Comparison between the current seismic hazard map (MPS04) and the updated map under discussion (MPS19s). The left panel shows absolute differences for expected peak ground acceleration, the right panel shows percentage differences. Red areas are those for which the peak acceleration increases from the old map to the new one, blue areas mean that it decreases. Expected peak ground accelerations considered for these maps are those that have a 10% probability of being exceeded over 50 years. Map produced by Centro di Pericolosità Sismica of INGV for the Civil Protection and provided to Nature Italy by CPS.

Doglioni says that he is working, together with a group of INGV researchers and without any external funding, on a new map which adopts a quite different approach from the one used so far. “We hope to have a prototype for Central Italy ready by the end of the year”, he says.

As the process continues, Italy still waits for an update of its seismic hazard levels, and thus of its building codes. The new map, for example, would rise the hazard levels in the Po valley, a highly populated area hit by a strong earthquake in 2012. "Areas in the Piedmont, Friuli, Campania, Umbria and Alto Adige regions would also see their seismic hazard rating increase with the new map", Meletti says.