Muographic imaging with a multi-layered telescope and its application to the study of the subsurface structure of a volcano

Abstract

In conventional muography observations using two detectors for muon tracking, the accidental coincidence of vertical electromagnetic showers generates identical trajectories to the muon tracks. Although muography has favorable properties, which allow direct density measurements inside a volcano, the measured density is lower than the actual value due to these fortuitous trajectories. We performed muography of Usu volcano, and confirmed that, in comparison with a use of two detectors, background noise levels were reduced by more than one order of magnitude using seven detectors for selecting linear trajectories. The resultant muographic image showed a high-density region underneath the central region of Usu volcano. This picture is consistent with the magma intrusion model proposed in previous studies. To clarify the three-dimensional location and actual size of the detected high-density body, multidirectional muographic measurements are necessary.

Plug Formation Imaged Beneath the Active Craters of Sakurajima Volcano With Muography

“…The application of cosmic muons has a potential to obtain the subsurface density structure of these craters and reveal the cause of deactivation of Showa crater and activation of Minamidake. Muography allows to image the shape of the magma either deposited or intruded Nishiyama et al, 2014Nishiyama et al, , 2017Tanaka & Yokoyama, 2013;Kusagaya & Tanaka, 2015), empty pathways Tioukov et al, 2019), magma degassing , magma ascent and descent , and hydrothermal activity inside lava domes (Jourde et al, 2016).…”

“…Muography allows to image the shape of the magma either deposited (Tanaka et al, ) or intruded (Tanaka et al, ; Nishiyama et al, , ; Tanaka & Yokoyama, ; Kusagaya & Tanaka, ), empty pathways (Tanaka et al, ; Tioukov et al, ), magma degassing (Tanaka et al, ), magma ascent and descent (Tanaka et al, ), and hydrothermal activity inside lava domes (Jourde et al, ).…”

Cosmic Ray Muons as Penetrating Probes to Explore the World around Us

“…This idea, exploited for the first time by Nagamine et al in [7] and Tanaka et al [8], has received an increasing attention in recent years, and a variety of projects, detector prototypes and operational activities have been reported. Important contributions to the field have been given by the Japanese collaboration leaded by H.K.M.Tanaka [8][9][10][11][12], which has employed a muon telescope made by several detection planes with scintillators with PMTs separated by Lead plates, by the Diaphane Collaboration [13][14][15][16], which carried out various measurement campaigns in several locations of the world (in France, Italy and Philippines) with scintillator-based muon telescopes, by the TOMUVOL Collaboration [17], employing resistive plate chambers detectors, and by the MU-RAY Project [18,19], which has employed a muon telescope based on scintillator strips with SiPM photosensors for the exploration of Mt. Vesuvius in Italy.…”

Muography

“…Since high-energy muons have a stronger penetration power than X-rays, this technique can create projection images of hectometric to kilometric sized objects. Although there are limitations to the targetable size of the objects that can be imaged by muography, researchers have applied this technique to various scientific targets that include volcanoes [such as Asama, Japan [1][2][3], Satsuma-Iwojima, Japan [4,5], Showa-shinzan, Japan [6], Usu, Japan [7], Unzen, Japan [8], La Sourfiere, France [9,10], Puy de Dome, France [11], Stromboli, Italy [12] and Etna, Italy [13,14]], seismic faults in Japan [15,16], ancient architecture [such as the Egyptian pyramids [17][18][19], and Mt. Echia, Italy [20]], and industrial plants [including electric furnaces [21] and nuclear reactors [22]].…”