After reading this article on the LAT website I assumed the old building I now live in had been retrofit during its renovation, but I wanted to make sure so I emailed Louise who works in the rental office and she forwarded the question on to the folks in charge of construction for The KOR Group and here is what Colin Fisher had to say:
Both 121 and 560 were both completely seismically retrofitted as part of the new construction work and brought up to current seismic code.
The buildings the article is concerned with are non-retrofitted buildings, such as 121 and 560 before we did our retrofit.
In that article John Martin, head of one of LA’s biggest structural engineering firms, talks about exactly what we did to retrofit the building, which is building a shear wall to strengthen against lateral forces imposed by earthquakes.
You can most easily see the new shear walls (the most visible part of the retrofit) in the North Unit in 560 along the west wall. You can also see a major shear wall in front of Taisei’s office onsite in the 560 retail space. All of the 121 shear walls have been painted over, so they’re not readily visible as ‘different’ from non-structural walls.
Now, as to how big of an earthquake it would take to reduce the building to rubble. The building is actually designed specifically so that it won’t catastrophically fail. In other words, if there is a massive earthquake and part of the building fails, the rest won’t come tumbling down.
The best way to visually see that is to look at post-Northridge Earthquake photographs. You’ll see buildings that are partially collapsed where a column failed and part of the building collapsed, but the rest of the building stayed up.
The Northride Earthquake was a 6.7 and I don’t remember any buildings failing catastrophically.
And here is what Blair Besten added:
We were required to retrofit when we bought the building in 2001. This
construction was completed this year. The giant, concrete walls you see
(some in center and some opposing) are constructed for this purpose. Look
in the retail spaces if you want to see them in their unpainted, plain gray
concrete state. Louise, if you sit at your desk you are facing one that was
I have no idea what magnitude we could withstand, but I imagine if it’s too
high up on the Richter scale we will be visiting the same place in the sky
as the rest of the City. At least we can rest knowing ours is the newest
retrofit, and therefore one of the safest places to be in that event.