The proposal to build a new city hall and police station on the South Wind property (“Cannon Beach gets a reality check on South Wind,” The Daily Astorian, Dec. 24) is ill-advised economically, as well as geologically. The property is located within a large landslide mapped by state geologists and published in 1972. The marine sedimentary rocks in this region are highly landslide prone, with an estimated 70 percent of the entire upland area of this portion of the Coast Range having undergone some type of downslope movement in the past, according to the 1972 state report.
As a geologist, I mapped landslides along most of the developed shoreline of Clatsop County for the Clatsop-Tillamook Intergovernmental Council in 1977 and 1978, and can attest to the instability of much of the region, especially on moderate to steep slopes.
When weighing the risk of tsunamis versus landslides it should be kept in mind that major earthquakes, such as those generated along the Cascadia Subduction Zone, also commonly cause large landslides. This, in combination with the property having been largely logged off, make it a poor choice for development.