Are You Living In a Dangerous Building?
Seattle Open Data Program Shows At-Risk Structures
Seattle is in a high-risk earthquake zone.
According to the City’s Department of Emergency Management, the highest hazard or danger in Seattle right now is an earthquake.
The City sits in a fault zone.
- That’s a thin slice of crushed rock sitting between two blocks of the earth’s crust. When there’s an earthquake, the two blocks slip or slide more easily.
- The fault zone runs east/west through the center of the city.
There’s also a risk of a tsunami.
- It’s possible that a large fault zone earthquake would produce a wave up to 16 feet high that would strike the downtown area within minutes.
The identification and study of all URMs is an important part of earthquake preparedness.
What’s a URM and why do I care?
A URM is an Unreinforced Masonry Building.
That’s a building that doesn’t have reinforcing
These are buildings in Seattle that have been identified as unreinforced. That’s important because they might need retrofitting to make them earthquake-proof.
Seattle’s Open Data Program
Open Data is a database that takes the information generated by the City and makes it available to the public. The idea is to increase transparency, accountability, and comparability.
The program allows the public to browse and search the data, search for reports that have already been created, and create their own reports.
Seismic data is an important tool the City is using to evaluate and plan for the likely event of a catastrophic earthquake occurring on the Seattle Fault Zone.
The City of Seattle IT department has produced a great map from the data in their database and has presented details of URM’s in an easy-to-use form.
There are several filters available in the interactive map.
Building Use Type
- Residential, commercial, schools, and mixed-use are general use types included.
Risk Category
- Emergency buildings and schools.
- Buildings over three stories in poor soil* areas plus buildings with more than 100 occupants.
- All other URMs.
*Poor soil is an important factor in risk analysis when you’re looking at potential earthquake damage.
Hard rock, dense soil, mud, or artificial fill react in different ways to the shaking of an earthquake, and damage to buildings located on the soil is affected.
Projected results use two general characteristics of soil in determining risk.
- The softness of the soil or rock.
- The total thickness of the sediment above the bedrock.
Map View
You are able to change the view on the map to include different building heights and also select the specific risk category you’d like to include.
After poking around a bit, I realized there are a lot of schools over 3 stories high that are unreinforced. If an earthquake hit during school hours, it could be devastating.
I decided to look at the worst-case scenario, which would be the highest building in a poor soil area with more than 100 occupants.
There is a building at 3100 Airport Way S, a 7 story residential building built in 1939 that is unreinforced. The soil in the area is rated as poor, which makes it more susceptible to earthquakes.
There are 6 commercial/mixed-use 7 story buildings in the 1st Avenue, King Street area built in the early 1900s that are unreinforced.
A quick adjustment of the height to 6 stories, reveals quite a few more buildings in that area of unstable soil, several of them are mixed commercial/residential, which puts residents at a higher risk.
What is the City of Seattle doing about URMs?
The National Development Council provided Seattle with a report with recommendations on retrofitting URMs in May 2019.
It’s an interesting read and there is an Executive Summary that sets out a great analysis of why seismic upgrades benefit both private owners and the Seattle public as a whole.
Private owners of a URM will see the benefits of increased safety and resilience in the event of an earthquake. This is a long-term benefit and also benefits the larger public good due to increased safety. The cost of seismic retrofitting tends to outweigh these benefits in the short term.
The City of Seattle might consider incentives that ease the financial burden on individual owners while supporting compliance with the required seismic upgrades.
In the end, Seattle will be safer and more resilient overall.
*a version of this article appears on Newsbreak (by author)
Sources:
https://www.seattle.gov/emergency-management/hazards/earthquake
https://www1.wsrb.com/blog/the-effects-of-soil-type-on-earthquake-damage
http://www.seattle.gov/tech/initiatives/open-data/about-the-open-data-program
