Seattle, Washington, has one of the most progressive landslide ordinances and mitigation programs in the United States. The necessity for this is driven by concentrated winter precipitation, steep slopes, and glacial soils that are susceptible to instability. Early in the European development, engineers recognized the vulnerability of Seattle hillsides to landslides, particularly when the hillsides were disturbed. In this paper, we trace the history of mapping of landslide-prone ground in Seattle, started by Miller (1973), detailed by Tubbs (1974, 1975), and most recently catalogued by Shannon & Wilson (2000, 2003).

Owing to the...