Underground muography: the present status and outlook

Abstract

The emerging imaging technique, muography, takes advantage of highly penetrating and ubiquitous cosmic-ray muons, and has been applied to volcano eruption prediction, social infrastructure monitoring, and cultural heritage investigations in the world. Muons arrive from the upper hemisphere in every direction and thus, the topographically prominent objects can be targeted without the necessity of burying the detector. However, researchers have started to develop underground muography to apply the technique to investigations of buried ancient cities, mineral explorations, and underground water monitoring. This review describes the present status of the observational studies in which underground muography has been used. The outlook for the future deep underground muography will be briefly discussed.