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U.S. Geological Survey
Professional Paper 1661-E

Seismic Stability of the Duwamish River Delta, Seattle, Washington

By Robert E. Kayen and Walter A. Barnhardt

Color image shows color shaded-relief bathymetry of the Duwamish delta in Elliott Bay, offshore Seattle, Washington.
Color shaded-relief bathymetry of the Duwamish delta in Elliott Bay, offshore Seattle, Washington. Contour interval 20 m. Onshore part of image is from a U.S. Geological Survey digital orthophotoquad (DOQ).


The delta front of the Duwamish River valley near Elliott Bay and Harbor Island is founded on young Holocene deposits shaped by sea-level rise, episodic volcanism, and seismicity. These river-mouth deposits are highly susceptible to seismic soil liquefaction and are potentially prone to submarine landsliding and disintegrative flow failure.

A highly developed commercial-industrial corridor, extending from the City of Kent to the Elliott Bay/Harbor Island marine terminal facilities, is founded on the young Holocene deposits of the Duwamish River valley. The deposits of this Holocene delta have been shaped not only by relative sea-level rise but also by episodic volcanism and seismicity. Ground-penetrating radar (GPR), cores, in situ testing, and outcrops are being used to examine the delta stratigraphy and to infer how these deposits will respond to future volcanic eruptions and earthquakes in the region. A geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

Download Professional Paper 1661-E as an 18-page PDF document (pp1661e.pdf; 1.1 MB)

For questions about the content of this report, contact Robert Kayen

Suggested citation and version history

This is one of a series of chapters in Earthquake Hazards of the Pacific Northwest Coastal and Marine Regions, USGS Professional Paper 1661, edited by Robert Kayen. The others consist of:

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