28 August 2011
My wife Lily is an Ecuadorian citizen. She was born in Quito, and we have traveled there together. (She’s also a U.S. citizen.)
After the big earthquake on Tuesday, significant structural damage was reported at several Washington landmarks including the Washington Monument and the Smithsonian Castle. Another one, less recognizable to most folks, but key in our personal geography, is the Embassy of Ecuador. Not only is it an outpost of my wife’s dual citizenship, but it also happens to be located adjacent to Meridian Hill Park (a.k.a. “Malcolm X Park”), a few blocks from where we live in Columbia Heights.
Yesterday morning, after a pre-hurricane run through the Zoo (visiting those putative quake-predictors, the gorillas and lemurs), we detoured past the Ecuadorian Embassy to see if any of the damage was visible from the outside. Indeed it was. After a shower and some breakfast, we walked back armed with our cameras to document what we saw.
Here’s a view of the north side of the building, from the intersection of 15th and Euclid. Perspective is facing the southeast:
You can see that several of the gables near the roof have sustained severe damage, and that apparently they were clobbered by loose bricks launched off a disintegrating chimney above. Zooming in, we can see areas where the bricks apparently bounced down the slate tiles and damaged them on the way down.
As I indicated at the end of Wednesday’s post about damage to my condo, chimneys are a huge risk in earthquakes because they are (a) often constructed from unreinforced masonry which has very low shear strength, and (b) relatively massive, which gives them a lot of inertia. As the ground accelerates out from underneath the building, the chimney’s inertia keeps it where it was. Then, as it finally gets moving, trying to catch up to the rest of the structure, the building beneath it has switched direction, moving back in the opposite direction. Without some internal or external reinforcement like rebar, this is a sure recipe from breaking your chimney into chunks. If your chimney is four storeys above street level, that can present problems for anyone on the sidewalk below.
Down the block a bit, looking back at the same scene, but from a different perspective – view is now towards the southwest:
And a zoom-in on the stub of the chimney itself:
Pre-crumbled structures like this are a big reason that we should still be vigilant during aftershocks, even if they are lesser in magnitude than the original quake (a point also made by the “5 myths about earthquakes” article in yesterday’s Post that you should definitely read).
Using Google Map’s “streetview” feature, I was able to get a look at what this particular chimney looked like before the earthquake last Tuesday:
We walked a bit further down, and saw that on the alley to the east of the embassy, another chimney had partially collapsed. They had already wrapped the top of this one in plastic, a procedure motivated in part by impending arrival of Hurricane Irene.
Note the guy cleaning up below, and also notice the chimney brace, wrought iron and with a decorative filigree added on:
Notice how only the chimney above this strut snapped off – the brace helped keep the lower portion of the chimney mechanically bound to the rest of the building so that they moved together during the earthquake. Shear was thus minimized for the lower portion of the chimney, and accordingly it did not fail.
Screenshot from Google Maps “streetview,” with former position of chimney highlighted by arrow:
Scenes like this should remind us city folk that during an earthquake, it’s better to shelter in place (indoors, under a desk or in a doorway) than to run outside onto the street. Total building collapse is rare; flying debris is common. If you are outside, move the heck away from buildings – and keep in mind that unreinforced masonry may be on its way down to meet you.