Characterizations of landslides in the Puget Sound and Lake Washington

Abstract

Lake Washington and the Puget Sound are home to many conditions that allow for the generation of landslides. In this paper, I used high-resolution multibeam, seismic reflection, and chirp data to characterize three landslides: one in Juanita Bay, one near Denny Park, and one south of the Mukilteo Ferry landing. I determined that the two types of landslides, those that originated as a failure of a river delta and those that began with a more general hillslope failure both originated subaqueously. The main difference between the two varieties of slide was the runout of the slide, the distance between the headwall and the eventual location of the failed material. The landslide examined that originated as a result of a delta failure, the Juanita Bay slide, had a runout over twice as long, 1.2 km, as the average runout of the landslides generated by hillslope failure, 500m. If this trend holds true, runout could become a way to determine the original conditions of landslide generation.