Unreinforced masonry buildings are the most dangerous of all structures in an earthquake, said Wilfred D. Iwan, director of the Earthquake Engineering Research Laboratory at Caltech in Pasadena.
"They were built at times when the concerns about earthquakes were not as great, codes were not as
strict and building materials were not as highly rated as they currently have to be," said Iwan
of the Covina buildings, some of which date to the late 1800s.
But relatively simple measures, such as anchoring roofs to walls with metal bolts and plates, are cost-effective and would keep roofs on masonry buildings from quickly collapsing in the event of an earthquake, said Iwan
"Citizens should demand these types of improvements - they are the ones who work, shop and in some cases even live in these buildings," he
said, adding that a magnitude-6quake would cause significant damage to an unreinforced masonry building.