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Mt. Asama and cosmic rays

October 6, 2009
Active vent of Mt. Asama (photo: Tokyo University)

The active vent of Mt. Asama (photo: Tokyo University)

I love the ingenuity of Japanese volcanologists.

After drilling into Mt. Unzen and sending unmanned machines in to build sabo dams, the New Scientist reports this week that scientists from Tokyo University have demonstrated a technique to measure the mass of material inside a volcano using cosmic radiation. They have “looked” into Mt Asama!

By measuring very complicated-sounding particles called muons, which are formed when cosmic rays interact with our atmosphere, the Tokyo scientists have been able to measure how they pass through the solid Earth. Passing through rocks of different densities the muons are absorbed at different rates, thus under a volcano one can locate molten magma. Understand?!

Essentially, they have been able to “scan” the volcano and come up with a picture of what its inner structure might look like – analogous to an MRI scan to view an unborn baby, say. At Asama volcano, they were able to do this before and after an eruption (in February earlier this year) and calculate just how much material was erupted. The answer? Over 30,000 tonnes – puny in terms of big eruptions, but an accurate figure compared to estimates of total ash fall.

This now means that volcanologists may be able to look at the insides of a volcano like never before: an obvious benefit for monitoring activity. One day they might even be able to see “shifting magma” – a curious insight into the world below.

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6 Comments leave one →
  1. October 7, 2009 1:27 am

    Interesting post! Thanks for letting us know about it.

  2. October 7, 2009 12:29 pm

    Very, very cool. My room-mate at uni did his graduation thesis on muons – they are formed when protons hit the atmosphere at such enormous speeds that there is a nuclear reaction that decomposes them into their sub-atomic pieces. Man, science is awesome.

  3. October 11, 2009 1:14 pm

    Hi guys, thanks!
    Yep, science can be pretty awesome and despite the infuriating formality of their universities/research institutes, Japanese scientists do get round to doing some amazing crazy stuff! Long may it continue 🙂

  4. wesu permalink
    October 14, 2009 12:19 pm

    what an amazing aerial photo of Asama! I know you didn’t take it, but it’s really fascinating to see that the hiking trail is completely buried under the ash. They’ll definitely have to blaze a new trail once that crater starts to settle down. I’ve got an old aerial photo of Asama lying around which shows the path before the eruption. I’ll send it to you if I can remember where I put it.

  5. December 9, 2009 7:38 am

    This is fascinating – I wonder what kind of structures the scientists discovered under Asama. Have they published any graphics?

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