City authorities and property owners in Los Angeles are making strides in retrofitting the kinds of apartment houses that were particularly susceptible in the earthquake in Northridge in 1994. This week, tens of thousands of houses were toppled and damaged by the devastating — and deadly— temblor that hit 25 years earlier.
As of this month, 1,500 soft-story houses have been retrofitted and, according to statistics from the construction and security department of the city, approximately 6,400 are in progress.
Owners have yet to submit retrofitting plans for approximately 5,000 structures, the first significant benchmark in the process. But for all the 12,865 soft-story structures that need seismic upgrades, “ordering to conform” has been released.
The orders are the first step in the compulsory retrofit program of the city, which requires owners to either provide evidence that their buildings have been retrofitted or file plans to do so within two years.
Chief resilience officer Marissa Aho of the city called the advancement “really interesting news.” “We’re ahead in terms of the amount of houses” that have so far met their two-year compliance date, tells Aho.
She said the city first made an effort to send orders to the owners of larger buildings, so the retrofits would start as quickly as possible for the majority of the units they needed.
Soft-story buildings are wood-frame structures where the first story is mainly open— like the famous dingbat-style apartment houses in LA that have open room on their first floors for parking.
The earthquake in Northridge revealed the vulnerabilities and spread of these kinds of structures across the town.
Approximately 49,000 apartment units in LA were demolished or severely damaged as a result of the earthquake in Northridge; two-thirds of these were in soft-story structures, according to a 2006 study from the California Public Policy Institute.
Twenty-one years after Northridge, the town launched a program in 2015 requiring estate owners to reinforce these houses to resist earthquakes. It started sending notices in May 2016 to estate owners, according to the construction and security department of the city.
At this moment, retrofits on 608 soft-story structures were finished last year and, according to the mayor’s office, nearly 4,000 retrofits were in progress. The fresh figures indicate that since then these figures have increased at least.
Do you need retrofits for your construction?
To verify, enter your address in the Building and Safety Department of Los Angeles database and click on “soft-story retrofits.” Retrofits are also needed for nearly 1,500 pre-1977 constructed non-ductile concrete houses, another type of structure likely to collapse. Seismologist Lucy Jones identified them as “the most deadly buildings when they fall.” By the end of 2018, the city had issued orders to comply with approximately 1,200 concrete buildings that were not ductile. The retrofitting method has been started by owners for about 160 of those constructions. They have to finish building for 25 years.
Mandatory construction retrofits are component of a bigger plan to prepare the town for the climate and bounce back from a major earthquake published in 2014.
The plan produced a range of suggestions directed at improving earthquake preparedness, including upgrades to water distribution systems and mandating less probable to topple cell phone towers in a quake.
With a 93 percent chance that an earthquake as big as (or bigger) the deadly Northridge quake will strike Los Angeles again in less than 30 years, upgrades to the city can not come as quickly as possible.