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Sea-Floor Sunday #35: Nisqually Delta, Puget Sound

November 23, 2008

This week’s Sea-Floor Sunday image is from the Nisqually Delta in southernmost Puget Sound, near Olympia, Washington —  I suppose this isn’t technically the sea floor … but hey, it’s bathymetry data … close enough.

The reds/yellows represent shallower regions, the blues/purples are deeper. Distance across image is ~10 km.


credit: USGS Western Coastal & Marine Geology (

If you click on the image you’ll go to the USGS page where I found it. One of the main objectives of collecting this data was to examine potential changes caused by a 6.8 earthquake in this area in 2001. The bathymetric data above was collected only a few weeks after the earthquake. The researchers note that the relatively steep scarp along the northeastern delta front (from green to blue colors) is a landslide scarp from an older event (because it was visible in data acquired prior to the 2001 quake).

The main page of that Open File report has links to more information about other deltas in Puget Sound that were examined at the same time and data you can download. This page will link you to more bathy images.

see all Sea-Floor Sunday posts here.


2 Comments leave one →
  1. November 23, 2008 6:40 pm

    Brian, are those big ripples in the shallower water?

  2. November 23, 2008 7:35 pm

    I think so … some of those features look like sand waves, but the texture is a little weird to me.

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