A Method for Probing Structure of Fault Fracture Zone with Cosmic Ray Muons

― Muography of Fault Fracture Zone ―

Abstract

  Recently, “Muography” technique for probing inner structure using cosmic ray muons is making progress remarkably. Visualization of density structure of inner volcano is one of the remarkable results. However, this technique could be applied to only the structure above the detector, because of its technical characteristic. Therefore, most of former studies using muography technique target object which are above the ground, such as mountain. We developed new observation system to extend observational target to underground, especially seismic fault.

The observation system has been installed at Atotsugawa, Kamioka, Hida, Gifu prefecture where the part of Atotsugawa fault zone. We performed structural survey of the fault zone to depth of 100 m. Then, we observed a sign of average density change caused by the fault zone which exists around the borehole.

  In near future, we extend the observation depth to 300 m and perform for detail investigation.