Mt. Asama and cosmic rays
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.