Muographic observation of density variations in the vicinity of minami-dake crater of sakurajima volcano

László Oláh, Hiroyuki K.M. Tanaka, Gergő Hamar, Dezső Varga

Research output: Article

1 Citation (Scopus)


Muography is an innovative imaging technique used for inspecting and monitoring density-length variations of large-sized natural or human-made objects based on the measurement of the absorption rate of cosmic-ray muons. The first large-sized, high-resolution muography observatory based on Multi-Wire Proportional Chamber (MWPC) technology is being developed to monitor the mass density variations in the vicinity of Minami-dake crater of Sakurajima volcano. We found that the track rates provided by five ongoing tracking systems with a total surface area of 4 m2 are stable within ±3% from the backward direction, which demonstrates that the MWPC-based Muographic Observation System (MMOS) is applicable for the detection of average density variations above 2%, which is well below the practical limit of 5%. We quantified the time resolution of the designed muography observatory by modeling the muon flux across the volcano; the average density-length variation of 5 (10)% is expected to be detected within 5–20 (2–8) days at a 1σ (68%) confidence level (CL) with an MMOS orientation of 10.86 above the horizon. An automated analysis framework was developed as a data base for raw data reconstruction, analysis, and preparation, and which is accessible via web-server. We observed a more than 2σ CL decrease in average density across the West side of Crater A during the ongoing data collection period. The observed density decrease suggests that the amount of material has decreased inside Crater A due to the consecutive eruptions of Minami-dake during the data collection period from November 30, 2018 to January 11, 2019.

Original languageEnglish
Pages (from-to)701-712
Number of pages12
JournalJournal of Disaster Research
Issue number5
Publication statusPublished - aug. 2019

ASJC Scopus subject areas

  • Safety, Risk, Reliability and Quality
  • Engineering (miscellaneous)

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