Ocean Maps Dive Deep
Up Close and Personal With Landscapes of the Abyss | Source: Earth.Columbia.Edu
Starting today, armchair explorers
will be able to view parts of the deep ocean floors in far greater
detail than ever before, thanks to a new synthesis of seafloor
topography released through Google Earth. Developed by oceanographers
at Columbia University's Lamont-Doherty Earth Observatory from
scientific data collected on research cruises, the new feature
tightens resolution in covered areas from the former 1-kilometer
grids to just 100 meters.
The ocean floors contain dramatic landscapes--volcanic ridges,
lofty peaks, wide plains and deep valleys-but most areas remain
mapped in less detail than the surfaces of the Moon and Mars.
The new, sharper focus is currently available for about 5 percent
of the oceans-even at that, an area larger than North America--and
provides spectacular scenery, including the huge Hudson Canyon
off New York City, the Wini Seamount near Hawaii, and the sharp-edged
10,000-foot-high Mendocino Ridge off the U.S Pacific Coast.
Google's new 2011 Seafloor Tour takes you to some prime spots,
such as the Pacific Ocean's Lamont Seamounts (named for the institution)
and Mendocino Ridge, where the Juan de Fuca plate slides toward
western North America, and where an earthquake could potentially
send a massive tsunami up onto land.
Viewers can use the "ground level view" feature of Google
Earth to take them to the seafloor for a closer look at the terrain.
To find which areas offer greater detail, users can download a
plug-in, the Columbia Ocean Terrain Synthesis. This provides an
extra layer to the conventional Google Earth imagery, showing
the tracks of research cruises that have produced the higher resolution.
(For those who really want to dive in, there is information on
the cruises themselves, and even the original bathymetry data.)
A second virtual tour, Deep Sea Ridge 2000, fueled by the new
synthesis and produced by Lamont-Doherty scientist Vicki Ferrini
and colleagues, takes visitors to see seafloor hydrothermal vents
spewing lava and hot liquids, and to learn about the creatures
that thrive there.
In addition to providing intriguing imagery, the more accurate
data reflected in the pictures is helping scientists understand
the risks posed by some features, including earthquake zones.
"In spite of the importance of the oceans for life on earth,
the landscape beneath the sea is hidden in darkness and poorly
mapped," said William Ryan, an oceanographer at Lamont-Doherty
who, along with Suzanne Carbotte and their team, created the system
used to generate the imagery. "While we can map the surface
of planets from spacecraft in a single mission, to obtain comparable
detail of the hidden seascape requires visiting every spot with
a ship." (The 100-meter resolution in the new views is still
generally less than the resolution on land, which goes to centimeters
in some areas.)
The imagery is the result of hundreds of cruises by scientific
research vessels from many institutions traveling roughly 3 million
miles across the oceans over the past two decades. To create the
new maps, the team combined multi-beam sonar measurements into
Lamont-Doherty's Global Multi-Resolution Topography system. This
same database feeds the recently released EarthObserver, Lamont's
global scientific mapping application for iPads and other mobile
devices. The ocean synthesis was begun in the early 2000s, with
funding from the National Science Foundation. It is ongoing, with
the team continually adding new data. While most of the data assembled
so far has come from U.S. institutions, many foreign institutions
hold troves of mapping data, which the team hopes to tap in the
Lamont scientists have long been at the forefront of ocean-floor
mapping. Lamont oceanographers Marie Tharp and Bruce Heezen created
the first comprehensive map of the world's ocean beds, published
in 1977. In the 1980s, satellite measurements helped fill in gaps,
and another Lamont scientist, William Haxby, used these to compose
the first "gravity field" map of the oceans. These maps
revolutionized seafloor imaging by providing a uniform, if low-resolution,
view of the global seafloor. With the advent of multi-beam sonar
mapping, also in the 1980s, scientists began to chart the ups
and downs of the seafloor in much finer detail.
Even from the 5 percent now available, scientists have learned
much. For instance, researchers can see details of earthquake
faults and underwater landslides. Shifts in the seafloor can trigger
tsunamis, as shown by this year's disaster in Japan, and the 2004
wave that swept Sumatra. The sharper imagery helps scientists
assess the risk in various regions, including along the U.S./Canada
west coast. The maps also bring erupting mid-ocean ridges into
sharper focus and help scientists understand volcanic eruptions
on earth, the vast majority of which occur hidden far from view
on the ocean floor.
Other institutions that have contributed data to the effort include
the Monterey Bay Aquarium Research Institute, Scripps Institution
of Oceanography, University of Hawaii, University of New Hampshire,
University of Washington, the U.S. Coast Guard, the U.S. National
Oceanic and Atmospheric Administration, the U.S. Navy, Woods Hole
Oceanographic Institution, the Leibniz Institute of Marine Sciences
at the University of Kiel and the Hydrographic and Oceanographic
Service of the Chilean Navy.