Seattle and surrounding areas are the 2nd most earthquake prone areas in the country.  Seattle sits directly over a major fault in part of the Cascadia Subduction Fault Zone.  Recent studies have alarmingly show that Seattle and its surrounding areas are at a significant risk of experiencing a major earthquake (Magnitude 8.0-9.0) in the next 30-50 years. 

another recent study showed that in a m6.7 earthquake, currently more than 130,000 single family homes would suffer moderate or severe damage & more than 46,000 households would be displaced. 

Homes built in earthquake prone areas

Houses built before 1985 are at significant risk of damage and displacement in an earthquake.  During an earthquake the strength of a house is put to the test.  Ground forces try to tear it apart and in many cases, cause severe damage.  Building codes now require every house and building to meet higher structural design standards.  Houses built prior to or around 1985 though are likely unsecured to their foundation and weekly connected.

Homes built before 1985

If your home is not built on a concrete slab, chances are it’s built on a raised foundation. This means the house was built on a system of posts, beams and “cripple walls”These houses typically have basements or crawl spaces underneath them. They are susceptible to damage because the supporting structure under the house may not have been anchored to resist seismic forces.  Past earthquakes have shown these areas are highly susceptible to structural failures. 

Homes built on a raised foundation

Houses built on a hillside typically have raised foundations and crawl spaces as those described above and can experience similar failures. However, these failures tend to be more severe because the posts and cripple walls supporting the home are built at different heights due to the uneven terrain.

Homes built on

a hill

Garages are vulnerable areas of a house due to the large garage door opening.  Because of this large opening, the narrow walls on either side of the garage door must be designed to resist earthquake forces.  This is extremely important if there is a living space above the garage because these rooms add weight that the garage must support.  Current building codes require that these narrow walls be specially designed to resist earthquake forces.  Older homes, however, typically were not designed to address this issue and are more vulnerable to damage during an earthquake.

Homes with a living space above a garage