The purple colors are deeper water and nicely show the sinuous canyon. The canyon is between 1 and 2 km wide and up to 1,100 m (~3,600 ft) deep. The tight meander bends remind me of this place. This submarine canyon feeds the enormous Indus submarine fan, which is 1500 km (900 mi) long and 960 km (575 mi) wide, second only to the Bengal submarine fan in size.

Bathymetry of Indus submarine canyon (credit: http://www.abdn.ac.uk/~wpg008/PelagiaIndusCruise.html)

Here’s a zoomed-out map from Google Earth for context.

Clicking on the image below will take you to the page with the live feed.

Static image of this live feed: http://interactiveoceans.washington.edu/story/Live+Video

Here’s a map of the location of Axial Volcano and check out this page to learn more.

General plate tectonic map of the NE Pacific Ocean showing the North American, Pacific, Explorer, Juan de Fuca, and Gorda plates. The Coaxial Segment is just N of Axial Volcano along the Juan de Fuca Ridge. (credit: http://www.volcano.si.edu/world/vol_extra.cfm?name=Blanco%20Transform%20Fault%20Zone)

credit: The Daily Mail

I blogged about this channel system in June 2009 and showed a similar, although much less colorful, image in this post.

The image above and the following quote are from this article in The Daily Mail.

The undersea river – the only active one to have been found so far – stems from salty water spilling through the Bosphorus Strait from the Mediterranean into the Black Sea, where the water has a lower salt content. This causes the dense water from the Mediterranean to flow like a river along the sea bed, carving a channel and deep bank.

The second sentence of that statement is a good one — it explains the mechanism for the origin of this submarine channel system (i.e., saline density currents that hug the sea bottom) and mentions it forms a geomorphic feature similar to a terrestrial river. But the first sentence causes my inner nerd to itch a bit. Firstly, submarine channels are not “undersea rivers” — at least, I’ve never heard anyone else who studies these features call them that. The quote from the researcher included in the piece is simply painting a picture for a general reader that the geomorphology is similar to a river. Secondly, what exactly is meant by “the only active one to have been found so far”? If they mean the active submarine channel systems then, no, this is not the only active one — there are numerous submarine canyon-channel systems that have transmitted density currents in recent decades (e.g. Monterey, Var, Hueneme, Congo, etc.). Perhaps they mean the only active system in which a saline current is the dominant agent? I’m not sure about that — maybe some of my readers could comment on that.

Don’t get me wrong, a discussion about what aspects of submarine channels are similar to rivers and what aspects are different from rivers is a discussion very much worth having. In fact, having that discussion helps us understand these features much better. But, I’m not ready to let the mainstream press and the general public simply call these ‘undersea rivers’ and be done with it — there’s still far too much to learn.

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* pointed out by @jeffersonite last week

Here’s a beautiful shaded-relief image of Perth submarine canyon (see the GoogleEarth image at the bottom for regional context):

Perth submarine canyon (credit: Australia Department of the Environment and Heritage)

Here’s a blurb directly from the site about the mapping that was done in Perth Canyon:

Two of the voyages in 2005 focused on mapping benthic ecosystems (that is, ecosystems at the bottom of the sea) on the deep continental shelf and slope in Australia’s south-west to understand evolution and biogeography. The voyages in this region focused on the Perth Canyon, a unique feature 22 kilometres seaward of Rottnest Island off Perth. The Perth Canyon is as wide and deep as the United States’ Grand Canyon, and during summer, blue whales feed on swarming krill in upwelling zones around its rim. The remarkable marine species recovered and sea floor images captured during these voyages will inform marine planning in south-west waters.

Below is a GoogleEarth image for regional context:

I’ve rotated these images such that north is to the upper right corner. In this first image the width is approximately 100 km (60 miles). The top of the image is more-or-less the edge of the continental shelf, which is about 400 m (1,300 ft) deep. The bottom of the image is well onto the continental slope and greater than 3,000 m (9,800 ft) of water depth. Note how the Hudson canyon (and other smaller canyons) incise across the steepest section of the shelf edge and uppermost slope.

Shaded relief bathymetry, Hudson submarine canyon (credit: USGS Open File Report 2004-1441; http://pubs.usgs.gov/of/2004/1441/html/figures.html)

The image below zooms in on the upper reaches of the canyon. The relatively flat floor of the canyon near the bottom of the image is about a kilometer wide to give you a sense of scale.

Shaded relief bathymetry, Hudson submarine canyon (credit: USGS Open File Report 2004-1441; http://pubs.usgs.gov/of/2004/1441/html/figures.html)

Here’s a snapshot from Google Earth for regional context.

-  Also see this post from 2007 about the Hudson Shelf Valley.

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* FYI: I opened the PDF file in Illustrator and deleted all the linework and annotation to highlight just the shaded relief

I came across this fantastic perspective image of the Florida Escarpment and deep basin floor of the Gulf of Mexico (see the regional map at the bottom of the post for context). What you’re looking at is a backscatter image, which relates to the intensity of the returned signal (read more about seafloor mapping technologies here).

Backscatter perspective image of Mississippi Fan lobes (credit: Center for Coastal and Ocean Mapping, http://ccom.unh.edu)

If you look at the flat basin floor you’ll notice a dashed yellow line drawn in — this separates the the light-colored, or high backscatter, regions from the dark-colored, or low backscatter, regions. The lighter colored regions are interpreted to represent sandier sediment and the dark is muddier.

The finger-like, lobate shape of the boundary of those sandier sediments are submarine fan lobes that are constructing the Mississippi submarine fan over time. The next image below shows the same area but now in a regular map view.

Backscatter image of Mississippi Fan lobes (credit: Center for Coastal and Ocean Mapping, http://ccom.unh.edu)

The backscatter image on the submarine lobes reveals a complex texture of small channels traversing the seafloor. I’ve zoomed in a bit more in the image below. This rich geomorphology is created by many thousands of years of turbidity currents delivering sand and mud from the Mississippi delta front to the deep sea.

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This map below shows the regional context for the images above.

The images below (Fig. 8 from their paper) are perspective images of seafloor topography (bathymetry) where the warm colors are shallow water and the cool colors are deeper water. The shallowest part shown is a few hundred meters below sea level and the deepest, at the deformation front, is approximately 2,500 meters below sea level.

Note the strong east-west trend in the ridges and valleys of the deformed zone. These images remind me a lot of similar perspective bathymetric images of the Cascadia accretionary wedge offshore Oregon and Washington.

In this paper, Bourget et al. investigate the character of the turbidite systems that traverse this topographically complex continental slope. Submarine canyons and channels zig-zag their way down through this maze depositing sediment in the elongate basins behind uplifted ridges, commonly referred to as “piggy-back basins”. The patterns of sedimentation differ along the margin as a function of varying tectonic styles/rates and onshore sediment-feeder systems. Check out the paper if you want to learn more.

Here’s a snapshot from Google Earth showing the regional context for this area.

The first author of this paper, Julien, has commented on this blog in the past so I’m sure he’ll be happy to share more information — feel free to ask questions in the comment thread below.
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BOURGET, J., ZARAGOSI, S., ELLOUZ-ZIMMERMANN, N., MOUCHOT, N., GARLAN, T., SCHNEIDER, J., LANFUMEY, V., & LALLEMANT, S. (2010). Turbidite system architecture and sedimentary processes along topographically complex slopes: the Makran convergent margin Sedimentology DOI: 10.1111/j.1365-3091.2010.01168.x

Lake Baikal is a lake in southeastern Russia and part of the Baikal-Vitim rift system between the Siberian platform to the north and fold-thrust belts of Mongolia to the south. You can read more about the geology of this region here.

credit: http://users.ugent.be/~mdbatist/intas/intas.htm

Although not very wide, this lake is very deep — up to 1.6 km (1 mi) — and, in fact, the deepest lake on Earth.

Below is a nice 3D perspective image showing the bathymetry (light and dark blues) with the surrounding topography (greens, yellows, and reds).

credit: http://users.ugent.be/~mdbatist/intas/intas.htm

I realize this isn’t technically a “seafloor” image, but I do show bathymetric images from lakes from time to time.

The first image (below) is a regional map centered on Iceland. I found it on this article on the mantleplumes.org site.

North Atlantic and Arctic Oceans and surrounding regions (credit: http://www.mantleplumes.org/Iceland2.html)

The next one is from GeoMapApp and simply shows the position of the Mid-Atlantic Ridge, Iceland, and Eyjafjallajokull.

basemap created in GeoMapApp

Here is a nice perspective bathymetric image (found here) showing the relationship of Iceland to Great Britain, the North Sea, and Scandinavia.

Perspective bathymetric image of the Nordic Seas (credit: http://folk.uio.no/bjorng/tidevannsmodeller/tidemod.html)

While searching for images I came across a great site from Tobias Weisenberger that, among many other topics, included a page on the geology of Iceland. If you want to learn more about the origin and evolution of this area I recommend it. The image below shows the bathymetry in relation to the age of the Iceland plume (yellow dots in millions of years) and the active rift zones (red lines).

Bathymetry around Iceland, active rift zones, and age of Iceland plume (credit: http://www.tobias-weisenberger.de/6Iceland.html)

Although not a bathymetric image I figured I’d throw in this simplified geologic map (also from Weisenberger’s site). Note location of Eyjafjallajokull near the southern tip of the island.

credit: http://www.tobias-weisenberger.de/6Iceland.html

As I mentioned in my post on Friday (showing a video of a jökulhlaup) check out the Eruptions blog and The Volcanism Blog for continuing coverage of this geologic event.