Large Earthquakes & Tall Buildings

English: Mexico City Earthquake, September 19,...

English: Mexico City Earthquake, September 19, 1985. Eight-story frame structure with brick infill walls broken in two. The foundation also came off. Credit: U.S. Geological Survey Department of the Interior/USGS/I.D. Celebi Source:http://libraryphoto.cr.usgs.gov/cgi-bin/show_picture.cgi?ID=ID.%20Celebi,%20M.%2024ct (Photo credit: Wikipedia)

I always wonder how large buildings will sustain a large earthquake since both my husband and I work in high rise buildings.

I recently found an article that reviews possible scenarios with earthquakes and how various buildings will handle the stress from the shaking ground. What I discovered was interesting and a bit scary…

First, when it comes a 9.0+ earthquake many scientists really don’t know how “skyscrapers” will handle the prolonged seismic activity. For one thing, severe earthquakes are rare (thankfully) and the large earthquakes aren’t always striking urban landscapes.

Bottom line, we don’t really know.

There are some simulations that help illustrate what could possibly happen and the results were interesting. There is a theory that with a large 9.0 earthquake that tall buildings could possibly collapse since they are not designed to severely sway for up to 5 minutes. A wood-framed small home (per this research) could sustain the 9.0+ earthquake and possibly get out with broken windows and of course, damaged contents.  A brick building might partially collapse under the stress.

Here is the interesting part… say if you have a 7.0 earthquake (think Haiti) – which are often times shallow with a short and abrupt land movement for up to 60 seconds… these earthquakes could slide a wood-framed home off of its foundation, the brick building could totally collapse and the “skyscraper” might have minor damage.

The article also alluded to findings after the 1985 Mexico City earthquake and in that quake (around an 8.1 on the Richter scale) the small and tall buildings survived. Buildings with 6-15 floors had a difficult time absorbing the shock waves  therefore 60% of the buildings in this size range were significantly damaged or collapsed.

How a  building performs is the condition of the shaking and the engineering/design of the structure.

Whatever building type that you and your family live, work, or reside in… may it always be safe.

Source:

http://www.iris.edu/hq/files/programs/education_and_outreach/retm/tm_100112_haiti/BuildingsInEQs.pdf

The Turkish Earthquakes

English: Map showing the epicentre of the 1999...

English: Map showing the epicentre of the 1999 İzmit earthquake. Türkçe: 1999 Gölcük Depremi merkezi ve etki alanı (Photo credit: Wikipedia)

I spent a lot of time in Turkey for personal reasons and I got to know the country and I met many people along the way. For one thing, it’s a gorgeous country and they have amazing food, however, they are plagued with an active fault that produced two very serious earthquakes that toppled many buildings where many lives were lost. Granted many of those who perished were in buildings with un-reinforced masonry, however, it still doesn’t discount the fact that many people died.

I have heard  push back on preparations in the Northwest after referencing these incredible death tolls. In fact, some Americans think the Turkish deaths were a result of older building codes — Many Turkish buildings were older and the US building standards are much better.

Not so fast… not really… not always.

I know in Portland that geologists worry about roughly 1,600 structures in the downtown area. These are older brick buildings, like the ones in parts of Turkey, that couldn’t handle significant shaking. The earthquake in 1999 was only a 7.6… in the Northwest we are talking about a 9.0+.  That is exponentially worse than the Turkish quakes.

These brick buildings in the Northwest will be no match for megaquake. I know the going theory is duck and cover, however, in my personal (unprofessional opinion) if you are in an un-reinforced brick building…. cover your head and run… run for your life.

I knew of three people in the Gölcük earthquake (pronounced Gul-juck) — one person was on the 6th floor of his building and it collapsed as he slept. Amazingly enough he rode the collapsing debris down, dusted himself off and began searching for neighbors in the rubble. I had another friend who was on the second floor of her building, asleep in her bed, and the building collapsed on her. Her will to dig won out and in shock she dusted herself off and staggered down the street counting her blessings…. the last person I met was a survivor… a sole survivor… he lost 9 people in the earthquake. I was told he stood in line and the government issued him 9 death certificates. He lost his parents, siblings, a spouse, and two young nieces.

Anyone reading this, please take these warnings seriously and prepare. It may save your life.

Don’t forget to join us on Facebook (Facebook.com/cascadiaearthquake) and Twitter @CascadiaQuake