Post by Admin on Sept 5, 2017 1:34:33 GMT
depth to compressional boundary...
"...130 and 190 kilometers underground.
That boundary marks the bottom of continental plates,.."?
...but didn't the north American plate travel over the mantle plume?, the Bermuda hotspot?...isn't this very clear on satellite?...can you see where the scraping and scarring stop across the Atlantic?...just to the west of the mid-Atlantic ridge, and right where the plume begins?...wouldn't this mean the compressional boundary is at the depth of the ocean, and would mean a plate thickness of about 3-6.5km [2-4 miles]? [seems logical?]
[...though it appears the Eurasian plate is the only one still "attached" to the mantle?, as, all the others have been misplaced?, 13kya?, at the YDB?...;-]
Analysis of seismic waves finds runny rock layer where landmass ends?
"...Earthquake vibrations are revealing just how deep the continents beneath our feet go.
Researchers analyzed seismic waves from earthquakes that have rocked various regions throughout the world, including the Americas, Antarctica and Africa. In almost every place, patterns in these waves indicated a layer of partially melted material between 130 and 190 kilometers underground.
That boundary marks the bottom of continental plates, argue Saikiran Tharimena, a seismologist at the University of Southampton in England, and colleagues. Their finding, reported in the Aug. 11 Science, may help resolve a longtime debate over the thickness of Earth’s landmasses.
Estimating continental depth “has been an issue that’s plagued scientists for quite a while,” says Tim Stern, a geophysicist at Victoria University of Wellington in New Zealand, who wasn’t involved in the work. Rock fragments belched up by volcanic eruptions suggest that the rigid rock of the continents extends about 175 kilometers underground, where it sits atop slightly runnier material in Earth’s mantle. But analyses of earthquake vibrations along Earth’s surface have suggested that continents could run 200 or 300 kilometers deep, very gradually transitioning from cold, hard rock to hotter, gooier material.
That disagreement may exist, Tharimena says, because to study continental thickness, seismologists had previously analyzed fairly shallow earthquake vibrations that couldn’t show Earth’s structure in fine detail at depths greater than about 150 kilometers..."
...this investigation is very important, and crucial that it finds accuracy...
...how could the American plates have a thickness greater than the depth of the Atlantic ocean to the height of the tallest mountain?
...as the plates "drifted" along the sea floors, that is where the compressional boundary lies?
...am I right?
"...130 and 190 kilometers underground.
That boundary marks the bottom of continental plates,.."?
...but didn't the north American plate travel over the mantle plume?, the Bermuda hotspot?...isn't this very clear on satellite?...can you see where the scraping and scarring stop across the Atlantic?...just to the west of the mid-Atlantic ridge, and right where the plume begins?...wouldn't this mean the compressional boundary is at the depth of the ocean, and would mean a plate thickness of about 3-6.5km [2-4 miles]? [seems logical?]
[...though it appears the Eurasian plate is the only one still "attached" to the mantle?, as, all the others have been misplaced?, 13kya?, at the YDB?...;-]
Analysis of seismic waves finds runny rock layer where landmass ends?
"...Earthquake vibrations are revealing just how deep the continents beneath our feet go.
Researchers analyzed seismic waves from earthquakes that have rocked various regions throughout the world, including the Americas, Antarctica and Africa. In almost every place, patterns in these waves indicated a layer of partially melted material between 130 and 190 kilometers underground.
That boundary marks the bottom of continental plates, argue Saikiran Tharimena, a seismologist at the University of Southampton in England, and colleagues. Their finding, reported in the Aug. 11 Science, may help resolve a longtime debate over the thickness of Earth’s landmasses.
Estimating continental depth “has been an issue that’s plagued scientists for quite a while,” says Tim Stern, a geophysicist at Victoria University of Wellington in New Zealand, who wasn’t involved in the work. Rock fragments belched up by volcanic eruptions suggest that the rigid rock of the continents extends about 175 kilometers underground, where it sits atop slightly runnier material in Earth’s mantle. But analyses of earthquake vibrations along Earth’s surface have suggested that continents could run 200 or 300 kilometers deep, very gradually transitioning from cold, hard rock to hotter, gooier material.
That disagreement may exist, Tharimena says, because to study continental thickness, seismologists had previously analyzed fairly shallow earthquake vibrations that couldn’t show Earth’s structure in fine detail at depths greater than about 150 kilometers..."
...this investigation is very important, and crucial that it finds accuracy...
...how could the American plates have a thickness greater than the depth of the Atlantic ocean to the height of the tallest mountain?
...as the plates "drifted" along the sea floors, that is where the compressional boundary lies?
...am I right?