Viewing Inside the Earth

Roland Piquepaille writes "Last week, a study released by Princeton University said that geoscientists have captured images of the interior of the Earth by using techniques similar to body scanning by physicians. This study also revealed in-depth structures which might explain how our planet is changing -- and aging. They studied more than 86,000 earthquakes which occurred since 1964. And they found 32 "mantle plumes" which are believed to cause island chains, such as the Hawaiian Islands and Iceland. They have been conjectured thirty years ago, but this is the first visual evidence they exist. This overview contains more details and references, including a rendering of mantle plumes in action."

Comments

Hype

[adlai]

I would argue that slashdot has just bought into hype surrounding one scientific paper. Seismic tomography work has been incrementally improving for many years.

Moreover, I suspect this paper will be very controversial -- the inversion of tomographic data is necessarily model-dependent, and many scientists are going to be skeptical of the claim that the have settled the source claim of plumes once and for all. [It's much easier to understand why plumes would originate at the thermal boundary at the core; what causes a plume to begin if it starts somewhere in the middle of the mantle?]

Here's some interesting literature

[armando_wall]

...about the Earth's Core (fantasy):

At The Earth's Core, by by Edgar Rice Burroughs.

Re:hollow earth

[Neop2Lemus]

That was the most lunatic thing I've read in years. I can't believe I read it all either.

Re:Why not real body scanning techniques?

[mikerich]

My best guess is that there is no radiation that works well for it. you need something that is strong enough to pass through the planet, but is weak enough to be partially stopped by features you're interested in.

Bingo! Earthquake waves are the only things we know about that go through the planet. Even radio waves don't make it.

Best wishes,
Mike.

Re:seismic survey

[GeoGreg]

While understanding Yellowstone is certainly an interesting and significant problem, EarthScope will probably be of more immediate social benefit in helping us understand what's going on at the San Andreas fault system and the Cascadian subduction zone. The impacts of earthquakes in California and volcanic eruptions in the Cascades are much more immediate than the potential of a catastrophic caldera-forming eruption at Yellowstone. The more likely threat at Yellowstone is from localized hydrothermal (steam) eruptions. It would be nice to be able to get the tourists out of the way if one of those is about to blow. The local sesimic arrays already in place at Yellowstone are probably more useful in predicting these sorts of eruptions than EarthScope will be.

Re:Why not real body scanning techniques?

[GeoGreg]

To elaborate on mikerich's reply, EM waves (e.g. x-rays) attenuate rapidly in the earth. Ground penetrating radar, for instance, can penetrate about 10 meters in good areas. Experiments have been done with extremely high-powered GPR systems, but they tend to turn the ground surface into glass (not good from an airplane). Very low frequency electric currents generated by the interaction of the earth's magnetic field with the solar wind are used in the method known as magnetotellurics. You can see down maybe 100 km, but the wavelengths are so long that the resolution is very coarse. And 100 km is still just the uppermost mantle.