Yet another article about the "pending" and "overdue" major earthquake ready to take down the Northwest. Living and working over a major faultline, several actually, allows one to think about the "what ifs?"
Downtown Portland is directly over a major faultline which has the capacity to level most of the buildings in the downtown core. Most built before seismic standards, they are typically unreinforced masonary (including the building I work in); the most dangerous and unstable building material in an earthquake.
In addition, the soil type under the West Hills, is of a type and consistency that when under extreme pressure, i.e. 7.0+ on the Richter scale, it liquifies.
So, all in all, a 7.0 in the downtown area will cause 70-80% of the building to collapse, just before all of the soil from the West Hills comes crashing down on top of us in a massive landslide.
But the real fun would be a 9.0+ off the coast that wipes out the coast and sends a tsunami up the Columbia River flooding hundreds of thousands of people from their homes.
Live in Portland? Find out if you are going to die too! (2.3mb file)