If you look at the stats, there have been several incidents in the past 50 years that saw brick chimneys collapse, even if the house wasn’t harmed at all. To explain more clearly, let us take the Libby Rose’s historic Craftsman house for example. According to Rose, the front chimney fell down in the 1989 quakes, where her home was standing tall as ever. “They just fell all over the back. They broke the back gate,” she said.
Most of the earthquake safety experts overlook the safety risks a brick chimney can pose. However, if a chimney starts to collapse in an event of a seismic activity, the bricks can start flying around and even kill you. A recent study found that brick chimneys, that are more than 20-year-old, are too brittle and weak, and will not withstand a major earthquake. As per the reports, around 15000 brick chimneys were destroyed in the 1994 earthquake in LA, and if another one hits California in the next couple of years, most of the residential buildings downtown LA will be crushed to the ground.
According to Laura Whitehurst, a San Francisco-based structural engineer, “Once the cracks form [in the mortar], then it is very vulnerable. If there is nothing to keep it together, once it starts bending, then you get catastrophic failures when the bricks start falling out.” The recently passed law by the Los Angeles Building and Safety department mandates retrofitting or replacing a brick chimney that has been damaged in an earthquake, even slightly. Lawmakers have also released a list of older buildings that need to be retrofitted soon.
Earthquake retrofitting costs are usually high, as it requires you to incorporate advanced materials and construction methods to retrofit a building. However, to make sure everyone complies with the rule, lawmakers have also said that the retrofitting costs would have to be shared by the tenant and the owner. There are even loan facilities and grants for earthquake retrofitting in Los Angeles.