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Tuesday, January 26, 2016

Discovering The Deep

"It's a whole new perspective on how the Earth works. We've our eyes and ears on a part of the seafloor that's really dynamic."
Daniel J. Fornari, Woods Hole Oceanographic Institution, Cape Cod, Massachusetts

"We're seeing it come alive. It's exciting. We're just starting to understand what's going on."
Maya Tolstoy, marine geophysicist, Lamont-Doherty Earth Observatory, Columbia University, New York
This images shows bands of glowing magma from submarine volcano.
Credit: NOAA/National Science Foundation

Scientists are forever discovering incredible things about Planet Earth. Voyages of discovery of the past centuries to the present have probed the length and breadth, the surface geology and secrets of the Earth's mantle upon which we live and breathe, prosper and advance technologically, using our natural surroundings as a base and the resources under the Earth's crust to enable us to forge ahead, and now probes of the ocean depths have revealed astonishing new realities to wonder at and decipher.

Hot vents discharging immense water plumes in which Zooplankton flourish in the rich hunting grounds of the mineral-dense warm and buoyant water emitted, have alerted scientists to an entirely novel brave new undersea world with creatures never before imagined. Whale calls have been tracked feeding on swarms of these minuscule creatures, along with red shrimp, brown mussels, pink fish whose tails  undulate and tubeworms with bright red plumes packed together.

The waters are as hot as 120 degrees Celsius but they're packed with swarms of sturdy microbes. These hot springs appear to act as global recycling centers turning complex carbon resulting from aeons of dead oceanic life into simple chemicals capable of forming new life-organisms. "They replace it with material that's biologically reactive. They're the lifeblood of the deep sea", explained Jeffrey A. Hawkes of the University of Oldenburg in Germany.
The Turtle Pits site on the mid-Atlantic Ridge, consisting of two sulfide mounds and a black smoker chimney. Credit Center for Marine Environmental Research/University of Bremen, Germany

From January to June, eruptions such as these take place from the Pacific, the Atlantic and the Arctic Oceans. Dr. Tolstoy imagines this to be related to Earth's elliptical orbit around the sun which changes the power of the sun's gravitational grasp on Earth so that the magnitude of the tides squeeze the planet are timed accordingly. Those great watery eruptions like magma flowing under great power from above-ground volcanoes take place when the squeeze relaxes.

And these are indeed volcanic eruptions, deep undersea, with vents that extend in incredibly long lines. Over 65,000 kilometers, in fact, under the world's oceans, encircling the globe in great seams. These are the midocean ridges hidden deep below in pitch darkness, only known to oceanographers since 1973 for their volcanic nature. The ridges, lying over a kilometer and a half deep in the oceans of the world appear as long rift valleys powerfully shoving giant fields of gushing hot springs into the icy seawater.
The Nature Tower, part of Lost City on the mid-Atlantic Ridge. Credit University of Washington/University of Rhode Island/National Oceanic and Atmospheric Administration, Ocean Exploration Trust

As they do, tons of minerals are brought to the ocean floor from deep below, rich in precious metals as well. One tower in the Pacific Ocean assumed tremendous height, earning the name Godzilla for its 15 story-height. There, thickets of snakelike tubeworms and bizarre aquatic life find their homes in the heated water, preyed upon by prowlers like spider crabs. This is water sufficiently hot to melt lead, where temperatures have been measured as high as 415 degrees Celsius.

Scientists have pooled resources to study ridges off the West Coast of North America where a highly active ridge has been wired with hundreds of sensors and cameras, the monitoring available to  scientists from around the world. The observatory was conceived of by John R. Delaney, an oceanographer working out of the University of Washington. A matter of huge interest is how volcanism alters, since studies may conclude that eruptions of such magnitude may influence both the global sea and the temperature of the planet.

Most of the world's volcanic eruptions occur in these oceanic ridges; about 70 percent. They carry with them not only heat and minerals but gases like carbon dioxide. The Earth's molten interior restlessly churns and oceanic slabs also called tectonic plates gradually pull apart under pressure, enabling molten rock and gases to find an escape route.There are two dozen or so such crustal plates, with the mid-Atlantic Ridge representing the world's longest mountain chain at almost 16,000 kilometers.

Dr. Tolstoy theorizes that the ice ages that regularly appear every 1,500 years produce falling ocean levels as massive continental ice sheets grow, compelling greater numbers of eruptions with reduced ridge pressure, spewing elevated carbon dioxide levels into the atmosphere, trapping heat and warming the planet. The gigantic ice sheets gradually melt and the oceans are refilled. This is a theory that has stimulated predictable debate in the scientific world, struggling with the realities of Climate Change.

The observatory itself sits on the Juan de Fuca Ridge where the volcanic center is over 480 kilometers in length, in a line off the West Coast, from British Columbia, to Oregon. Divided into two parts, the observatory is operated on its northern portion by Canada and at the southern half by the  United States. The two sites have over 1,600 kilometers of cables, countless junction boxes and hundreds of sensors.

On the seabed lie tilt meters, cameras, seismometers, temperature gauges, hydrophones, chemical probes, pressure sensors and fluid samplers as well as mobile platforms placed along stepped moorings to enable readings to be taken high in the water column
A triangular array that was to be deployed to measure the temperature of a venting hot spring below the surface. Credit University of Washington/National Science Foundation-Ocean Observatories Initiative/Canadian Scientific Submersible Facility

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