Hawaiian hot spot's deep roots uncovered by scientists

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Washington, December 5 (ANI): A new study by an international research team has opened up a window into the earth to reveal Hawaii's deep roots, by suggesting that the Hawaiian hot spot is the result of an upwelling high-temperature plume from the lower mantle.

The project, called the Plume-Lithosphere Undersea Melt Experiment (PLUME), deployed a large network of seafloor seismometers at 73 sites off Hawaii during four research cruises over more than two-years.

It represented the largest ocean-bottom seismometer (OBS) experiment in the world, reaching deeper into the lower mantle than previous experiments.

Geophysicist Gabi Laske of the Scripps Institution of Oceanography at UC San Diego led the PLUME experiment.

Laske's research involves long-term, ocean-bottom earthquake monitoring to find and image the plume that gives rise to spectacular Hawaiian island chain of volcanoes and to better understand how they are fed by a super-heated plume from deep in the earth.

"The PLUME team has unambiguously traced the Hawaiian plume from the seafloor through Earth's mantle transition zone," said Laske.

The transition zone was previously thought to be a layer that obstructs whole-mantle convection between the core and the surface of the planet.

The seismometers were used to record the timing of seismic shear waves from large earthquakes (magnitudes greater than 5.5) around the world.

This information can be used to determine whether seismic waves travel more slowly through hot rock as they pass beneath Hawaii.

Combining the timing measurements from many earthquakes recorded on many seismometers allowed researchers to construct a sophisticated three-dimensional image of the Hawaiian mantle.

The large, 1,000-kilometers (621-miles) wide aperture of the seafloor ocean bottom seismometer network, developed at Scripps yielded unprecedented precision and resolution in a remote oceanic region and included SKS waves, a type of wave that travels through the earth's core, that was critical for extending the imaging down to 1,500 kilometers (932-mile) depth.

The images from the PLUME experiment provide strong support for the existence of a mantle plume beneath Hawaii.

Results of the project indicate a strong case for the existence of a deep mantle plume, which has fundamental implications-not just for Hawaii, but more generally for the form of convection in the solid Earth, Earth's composition with depth, its evolution over geologic time and how the earth releases heat. (ANI)

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