The problem of medieval villages and earthquakes

In Japan and California, they’ve spent billions on state-of-the-art earthquake and tsunami preparedness schemes. In poorer countries like Nepal, Haiti, and Indonesia, they’ve resettled survivors in less quake- or flood-prone areas. But Italy presents a fairly unique challenge for earthquake engineers: how do you make historic, medieval towns and villages safer without knocking the whole lot down?

Precariously perched along the spine of the Apennine mountain range, villages like Amatrice that were destroyed by Wednesday’s earthquake are cultural jewels, set in some of Europe’s most beautiful and unspoiled landscapes. You’re not going to stop people wanting to live there; you’re not going to prevent tourists from visiting; and the tectonic activity is unlikely to cease any time soon.

All you can do is try to mitigate the damage, try to keep the toll as low as possible. A strict building code is clearly a good place to start, but Italy already has one of the most stringent in the world.

In 2002, a moderate earthquake in relatively safe seismic territory – Modena, east of Rome – led to the collapse of a primary school in the town of San Giuliano di Puglia. A teacher and 27 primary school children, including an entire year group, died. An exhaustive seismic remapping followed and a new building code was drawn up based on Europe’s existing code, but adding even tighter restrictions. It took effect in July 2009, due to public pressure following the L’Aquila earthquake that claimed more than 300 lives in April of that year.

So why, if Italy has such a stringent building code, did so many people die – 267 and counting – in Wednesday’s earthquake, and why will people continue to be at risk the next time a similar seismic event rocks the picturesque Apennine region?

A cursory glance at the images tells you a great deal: many of the dead were sleeping in homes constructed centuries before building codes even existed.

“The law that was enforced after 2009… it’s a code that only deals with construction and renovation,” Michele Calvi, a professor of earthquake engineering at IUSS Pavia, told IRIN. “So, [there’s] no obligation to do anything if you’re keeping the building as it is.”

Advances in construction and technology have resulted in modern structures that can better withstand the impact of earthquakes. But there were also reports of some modern buildings collapsing, including a hospital, a police station, and a school, raising questions about the hundreds of millions of euros allocated for seismic retro-fitting following L’Aquila.

“Obviously the buildings weren’t all retro-fitted,” Brigitte Leoni, communications officer with the UN’s Office for Disaster Risk Reduction, told IRIN. “You need to do a risk assessment and evaluate your priorities – usually the critical infrastructures like hospitals are first priority. In Italy, they’re aware of it, and compared to other countries they’re really well advanced, but they have a lot of old buildings. After 2009, this was a measure they increased [retro-fitting], but it can’t be 100 percent.”

“There is not a safe and unsafe building. It’s just what you can do to decrease the possibility of collapse,” said Calvi, explaining that different prescriptions apply to different types of structure.

“When you’re dealing with a stone building, like most of these in this area, you can look at minor things like the connection between different floors and the walls, elimination of any structure that’s pushing against it, like arches. It’s not very expensive at all to do these things.”

For more modern, concrete buildings, Calvi suggested the addition of diagonal ties to take care of horizontal forces, the cutting of columns, and the insertion of seismic isolation units.

The cash-strapped Italian government doesn’t have the wherewithal to pump billions of euros into earthquake preparedness.

The writer is Chief Editor of IRIN