The Spanish government is facing calls for historic structures in the southern city of Lorca to be strengthened following last week’s destructive earthquake.
Ancient infrastructure “should be reinforced”
Engineers this week said ministers should consider work to reinforce the ancient city’s public buildings and infrastructure, so they can resist events like the 5.2 magnitude earthquake that struck the town last Wednesday.
“There are lots of buildings that predate the engineering means that we have for earthquakes,” said University of Cambridge geotechnical engineering reader Gopal Madabhushi. “You can’t really put a price on historic buildings, can you?”
“As with most European cities there is a lot of building stock which is pretty old and will be susceptible to an earthquake event,” added Arup associate director Ziggy Lubkowski.
Lubkowski said the need for Lorca’s historic buildings to be reinforced against earthquakes is likely to conflict with heritage concerns.
“It’s a difficult balancing act of maintaining that heritage without ruining the visual aspect of it, against trying to do something clever to improve the seismic resistance”
Arup associate director Ziggy Lubkowski
“It’s a difficult balancing act of maintaining that heritage without ruining the visual aspect of it, against trying to do something clever to improve the seismic resistance.”
The cost of such upgrade work would also be an issue. “The economic effects of doing a lot to the old building stock will be pretty huge, and it’s always a question of who’s going to pay for it. It can be expensive to do an adequate retrofit.”
Spanish prime minister José Luis Rodríguez Zapatero said no efforts will be spared for Lorca’s recovery and reconstruction. “We are not going to haggle over any economic resources for the reconstruction task,” he said.
More research needed
Reinforcement could be achieved in a number of ways, such as by using steel mesh or shotcrete, but it often changes the character and appearance of a building. “You need to try and tie the buildings together,” said Lubkowski. “If it is rubble masonry there is not a lot you can do. If it is good quality brick masonry there is more you can work with.”
In a historic city like Lorca, Lubkowski said, smaller, cheaper measures to secure parapets and other external features could go some way towards improving structures in the absence of a full retrofit.
But Madabhushi said seismic retrofitting of heritage buildings is an area of engineering that needs more research.