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Metro tunnels are one of the safest places during an earthquake, officials say

By Rachel Garcia
Published: Wednesday, August 15, 2012, at 08:58AM
Boarding the Metro Red Line at 7th / Metro Station Eric Richardson / blogdowntown

Riders board a Red Line train at 7th / Metro station in Downtown L.A.

DOWNTOWN LOS ANGELES — Every weekday Derek James takes three different trains from his home in Burbank to his job at USC, passing through subway tunnels along the way. He seemed discomforted at the possibility of an earthquake hitting during the underground portion of his daily commute.

"I don't even want to think about being down here during an earthquake," James said while standing in the Metro tunnel at 7th and Flower.

However, officials say tunnels are one of the best locations to find yourself when a quake strikes.

"Tunnels are the safest place during an earthquake because tunnels move as one unit with the ground," explained Murthy Krishniah, executive director of Transit Project Delivery for Metro.

L.A. Metro tunnels were designed in 1984 based on criteria developed by Metro engineers and the California Institute of Technology. Taking into account local fault lines, the structures were designed to withstand up to magnitude 7 earthquakes. The structures' test came in 1994 with the 6.7 magnitude Northridge earthquake, which the tunnels withstood without damage, Krishniah said.

In the event of significant shaking, underground recording centers are notified. The auto-setting in the system brings the trains to a complete stop, then reduces their speed to 5 mph or less, said Scott Norwood, emergency and preparedness manager for Metro.

Following large earthquakes, engineers inspect the tunnels, looking for cracks and other damage to the structures. Metro tunnels have not been significantly damaged due to past earthquakes, according to Krishniah.

"[During an earthquake], I would rather be in a subway tunnel than anywhere else," Norwood said.

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User_32

blinkie () on August 15, 2012, at 09:32AM – #1

"The structures' test came in 1994 with the 4.8 magnitude Northridge earthquake"

Northridge, a 4.8? According to the USGS it was a 6.7. Most 4.8s don't have a death toll like Northride did.


User_32

on August 15, 2012, at 10:07AM – #2

Corrected, Blinkie, thanks!


User_32

Scott M on August 15, 2012, at 12:18PM – #3

I think the subway structures are probably very safe--but getting trampled by panicked patrons--probably not so much...


User_32

David McBane on August 15, 2012, at 08:14PM – #4

Don't tell Beverly Hills they are safe - they will just say it is a conspiracy and they are destined to explode.


User_32

Barry P on August 15, 2012, at 11:36PM – #5

Universal Studios has done nothing to help perceptions of the subway in L.A. I can still hear the screams as that truck crashed through the roof of the flaming tunnel ... and the roar of the water flooding the station ...


User_32

BJBigler () on August 16, 2012, at 09:48AM – #6

From Metro's blog:

"There is no specific magnitude that subways are designed to universally withstand. The strength and flexibility the subway is designed for depends on the characteristics of earthquake faults in the area and their proximity to the structure being designed. In other words, the main question engineers ask is this: how strong is the ground shaking likely to be at the tunnels and stations?"

http://thesource.metro.net/2012/08/10/designing-a-subway-to-withstand-an-earthquake/


User_32

Rachel Garcia on August 16, 2012, at 02:32PM – #7

BJBigler-

Thank you for your input.

As mentioned in my article and as the blog post you quoted says, the tunnels were built taking into consideration the earthquake magnitudes that local faults are capable of producing. Local L.A. county faults were found capable of producing magnitude 7 earthquakes, according to Murthy Krishniah, the executive director for Transit Projects Delivery for Metro. Taking that magnitude into consideration, Krishniah told me that L.A. tunnels were designed to withstand "up to" magnitude 7 earthquakes.

Since the blog you quoted goes on to list different cities worldwide and the earthquake strengths that those places have experienced, I believe that the quote "there is no specific magnitude that subways are designed to universally withstand," refers to the fact that, worldwide, different tunnels have different strains depending on local faultiness. Therefore, the structure for an L.A. tunnel might not work for tunnels elsewhere.


User_32

DenOfLosAngeles on August 18, 2012, at 01:28PM – #8

Even though the Universal Studios Earthquake tram tour attraction simulates a big quake in a (Frisco) subway station it's over-exaggerated. During the earthquake Los Angeles subway stations came out of it better than expected with little or no damage.


Steven Harris on August 22, 2012, at 07:33PM – #9

If you get on YouTube you will find tourist videos in the Tokyo Metro subway lines during the big 8.9 earthquake there a couple years go. Very little is moving other than the trains rocking slightly. On the surface things sway, but underground deep inside rock little is happening.

http://www.subwayjoyride.com



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