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Detailed seafloor gravity map brings the Earth’s surface into sharp focus

by • January 18, 2016 • No Comments

Not so long ago the ocean floor was as unknown as the far side of the Moon. Now, an international team of scientists is via satellite data to chart the deep ocean by measuring the Earth’s gravitational field. The outcome is a new, highly-detailed map that covers the three-quarters of the Earth’s surface that lies underwater. The map is may already providing new insights into global geology.

  • Relief map of the Atlantic Ocean
  • Gravity map of the Indian Ocean
  • Relief map of the Indian Ocean
  • Gravity map of the Atlantic Ocean

Up until of a hundred years ago, the only way to learn anything of the bottom of the sea was to toss a piece of lead overboard on the end of a line. Measuring the line gave the depth and if you were quite sophisticated, you stuck a wad of wax on a depression in the lead to bring up a sample of the bottom. More sophisticated techniques were turn it intod, but at the end of the day, they were only weights and grabs on the end of a quite long string.

Things took a step forward with the invention of sonar, but actually with decades of intense work by the world’s excellent navies and scientific institutions, only a quite tiny fraction of the seafloor was mapped at a resolution that missed whole mountains. What was needed was a way of measuring the bottom showcases without having a ship passing over equite point to take direct measurements.

Choosing data of ESA’s CryoSat-2 and NASA/CNES’ Jason-1 satellites as well as older space missions, scientists of the University of Sydney have now taken a additional lateral approach. They utilized the data to turn it into a map of the Earth’s gravitational field by studying how the orbits of the satellites alterd, and of this deduced what the seafloor looked like.

The yett was based on the fact that the Earth’s gravitational field is far of uniform. Because of the Earth’s irregular shape and the presence of areas of denser materials in the crust, the field is quite unactually, with its pull varying of place to place. This can be measured in units called milligals, that is a alter in the pull of gravity by one thousandth of one centimeter per 2nd squared.

This alter in the Earth’s surface distorts sea level heights above them. By combining the orbital data with sea level heights and comparing them against direct bottom measurements via desktop analysis, a map of the sea floor can be drawn with resolutions down to objects 5 km (3 mi) wide. The outcome is a world map in shades of orange and red, that represent denser areas corresponding to underwater ridges, seamounts, and the edges of Earth’s tectonic plates, and darker blue areas for less dense areas revealing the deepest troughs and trenches.

This map is may already making new insights into the ocean floor, as stated by a team of the Scripps Institution of Oceanography and the US National Oceanic and Atmospheric Administration when studying an area of the Indian Ocean floor the dimensions of West Virginia or Tasmania. This area broke off of the Antarctic tectonic plate when it rammed into Asia at 15 cm (6 in) per year to turn it into the Himalayas a few 47 million years ago. Called the Mammerickx Microplate after seafloor mapping pioneer Jacqueline Mammerickx, it is actually the initially discovered on the Indian Ocean floor. The impact was so complex that the microplate spun like a ball bearing – yet at a geological pace.

NASA says that the new map can provide a advantageous belief of how the Earth’s plates move, that may lead to advantageous earthquake prediction. It can in addition prove valuable to prospectors, as well as surface ship and submarine captains.

Source: NASA


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