Infrasound, also known as low-frequency sound, describes sound waves with a frequency below the lower limit of human audibility. But I think the same complexity is what makes them beautiful, he said. University doctoral candidate Alvaro Diaz-Flores Caminero and undergraduate student Claire Pedersen were the lead authors of the paper. TUCSON, Ariz. (AP)  Natural underground caverns on the moon could be used to store frozen samples of Earths species in order to protect biodiversity in the event of global catastrophe, according to a University of Arizona scientist and his students. On the moon, pits in the ground lead to lava tubes, now hollow, that reach down some 8o to 100 meters underground, making them ideal for protecting precious cargo from the lunar elements.
pits in the ground lead to the death of an astronaut.
( z0 lead :ARG0 ( z1 bomb :location ( z2 ground ) ) :ARG2 ( z3 die :ARG1 ( z4 astronaut ) ) )
(z0 / lead-03
    :ARG0 (z1 / bomb
              :location (z2 / ground))
    :ARG2 (z3 / die-01
              :ARG1 (z4 / astronaut)))
pits in the ground lead to the death of an astronaut .
z1 :location z2
z0 :ARG0 z1
z0 :ARG2 z3
z3 :ARG1 z4