{ metropolis devoured }
a tribute to my san francisco

3/4 oz scotch whiskey
3/4 oz local politics
1/4 oz public policy
1/4 oz disaster preparedness
1/2 oz alamo square

Shake over neighborhood dives & venues, strain into a chilled cocktail dress, garnish with a sprig of gov 2.0, and serve.

Monday, June 28, 2010

Earthquakes are not new to San Francisco.

Today's 3.3 magnitude earthquake in San Francisco generated a response on my Twitter feed that I was frankly quite surprised to read: What do you actually do in an earthquake? I'd expect this from the Canadians, whose 5.0 caught many by surprise last week, but my own home town in earthquake country? I'd be betraying my profession if I didn't address at least some of the questions that seem to have folks concerned. Please keep in mind that this advice is regional in nature, and not all earthquake-prone regions have the same hazards, such as tsunamis. The durability of your building will also depend on the building codes of your country, and I am speaking strictly from building codes and seismic safety standard enforced in the US. If you're reading this from elsewhere, google your country's seismic safety building codes and see if there is a provision for life safety.

What do the numbers mean?

An event usually produces several different magnitude results that get reported during different phases of the event. The first numbers reported are based on a small and easily accessible number of seismic devices and are meant to get a quick picture of the magnitude out to the public. Later the results are recalculated using a larger number of sensors and the magnitude is often downgraded. Earthquakes are measured using several different models. The local magnitude scale (better known as the Richter Scale) is widely used, but becomes less and less precise with larger magnitude earthquakes (6 and above). The USGS uses the moment magnitude scale, which is an extension of the local magnitude scale, to accurately represent the size of earthquakes. The equation that calculates magnitude using the moment magnitude scale contains constants that make the results consistent with magnitude values produced by earlier scales, including Richter.

What do I do during the earthquake?

It's the same thing you heard in elementary school: drop, cover, and hold on.

In the event of seismic activity, however minor, one should immediately become aware of their surroundings. Because the performance of your building will greatly depend on the type of building material and what it's standing on, take into consideration the type of structure you're in and what sort of topography it's built on.

The first thing you should do is locate a sturdy table and get under it. If your table is from Ikea, like mine, I'd highly recommend getting under the table AND grabbing a large pillow to protect your head and neck. Thanks to modern building codes, our buildings are built to a "life safety" standard, meaning they may not be operable after an event, but they are generally built to not crush inhabitants.

The "triangle of life" (which advocates laying down next to a large object) theory does not work. Here's a Red Cross paper explaining why: http://www2.bpaonline.org/Emergencyprep/arc-on-doug-copp.html. If you don't feel like reading the whole thing, here's the gist: the evidence for using the "triangle of life" theory is mostly anecdotal and relies on many false assumptions about earthquake mechanics and hazards. It also relies heavily on photographic evidence from events in places where building codes are nonexistent. We have building codes. Even historic buildings have mostly been retrofitted to modern seismic standards.

The majority of injuries sustained during an earthquake are from falling objects and debris. You aren't getting under a table because the table will protect you from your collapsing house because your house is built to NOT collapse (though structural damage and lean may occur). You're getting under the table to prevent the light fixture, which is heavier than you think, from falling on your head. Same with that plant in a terra cotta pot on top of your bookshelf.

In the absence of a table or other similar surface you can get under, go and stand next to an interior wall, away from windows, bookshelves, light fixtures, or other objects that have the potential to fall. Grab a pillow of one is available to protect your eyes, head and neck.

Be aware of aftershocks and remain in a safe place in the building until it's OK to move. Aftershocks may not happen immediately and may not be as strong, but can still shake objects loose and create falling debris. There's no way to determine when aftershocks will happen, so just use your common sense and don't run out of the building the moment the shaking stops.

And if you are experiencing a significant earthquake while located near the ocean or the bay, move to higher ground as soon as it's safe to do so.

Things NOT to do:

  • Do NOT run outside. Unless you want to get knocked on the head by falling debris.

  • Do NOT attempt to stand in a violent earthquake. It'll throw you down anyway, and might injure you. Get down on your own.

  • Do NOT stand in the doorway. The doorway is not a safe structure in modern buildings. You'll get knocked by falling debris.

  • Do NOT use the "triangle of life" technique.

Resources that will help you get prepared:
  • Many people didn't actually feel the quake this morning. Props to your building engineer. Some mistook it for a passing train. If you want to know for sure, register your cell phone with Alert SF and they will send you a notification. I found out about the quake when I got the text. The USGS has a notification service as well. I generally avoid redundancy, but in this case I think registering with multiple services is a good idea.

  • Take simple steps to make your house safer. Secure bookshelves to the wall, make sure your heavier frames are on hung on closed hooks, secure heavy objects like pots and vases with earthquake putty or museum clay, and take other steps suggested on the Earthquake Country website.

  • Have a kit. You maybe be without essential services for 72 hours, and you'll need to be able to rely on your own resources. Go to 72Hours.org to learn what to put in yours.

  • If you live close to the ocean or the bay, take a look at the Tsunami Inundation Map to learn if you're in a tsunami risk zone.

  • Keep tabs on the San Francisco Department of Emergency Management. DEM is always engaging in opportunities to get preparedness tips and other relevant information out to the public. The website also contains all the most recent plans, updates to the 72Hour website, and plans for future exercises.

Alrighty. Any questions? Please feel free to ask via comment.


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