1. Alki Beach is an unfathomably dangerous place. It will kill us all.

2. Major threats to Alki Beach are landslides, earthquakes and tsunamis. 3. Damned if we do...

When we analyze the underlying geological structure of Puget Sound, it seems completely insane for anyone to live anywhere in that region! Alki Beach is located near the Seattle Fault Zone which lies under Puget Sound, and creates a significant dislocation along the fault plane. In a tsunami, the initial wave uplift can be up to 8 meters high between Alki Point and Restoration Point.

4.

Furthermore, the Sound is settled in an area of loose sediment from glacial till, which, along with soil deposits from erosion, cover in stratigraphic layers the underlying topography of the Sound. In the event of a seismic shift, this material can slip and slide under the water in the same way it might on land in a landslide this can contribute to the amplitude and velocity of the wave pickup, and cause tsunamis of an even greater magnitude.

5. ...Damned if we don't.

The Puget Sound region is settled on a foundation of loose sediment and layers of glacial deposits. Surrounding areas are largely composed of steep slopes topped with loose soil, which can come loose under the exertion of gravity, or with seismic activity such as earthquakes, thus causing landslides, many of which have the potential to be highly destructive and dangerous.

6. Many areas of Seattle are prone to landslides. This is due to its typically steep topography and its moist, post-glacial-type soil. 7.

Visiting Alki Beach, the loose, wet soil is evidenced by tilting signposts and utility poles, cracked streets, unstable foundations.

8.

Left: precarious building site. Below: mudslide into a house built at the base of a slope.

9. 10. Other concerns...

In West Seattle, Beach Road was closed down in January of 2010 because of a landslide caused by reckless deforestation techniques. In an area where erosion is a problem naturally, it is especially dangerous to remove vegetation that helps to hold the soil in place.

11.

In addition to the human activity which increases the likelihood of landslides, Alki's irregular erosion patterns (which result from its unique layering of sediment deposits and exposed bedrock) affords problematic wastewater drainage shifting soil increases susceptibility to leaks and spills, and any waste quickly finds its way into Puget Sound.