Muography. Группа авторов
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Название: Muography

Автор: Группа авторов

Издательство: John Wiley & Sons Limited

Жанр: Физика

Серия:

isbn: 9781119723066

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СКАЧАТЬ than expected. As an immediate solution, Rosas‐Carbajal et al. (2017) propose to separate the density sensed by gravity data ( ρ g ) and the density sensed by muography data ( ρ μ ) and relate the two vectors with an unknown constant bias (Δρ), written as ρ g = ρ μ + (Δρ, Δρ, ⋯, Δρ)T. This constant density bias is solved together with ρ μ . Lelièvre et al. (2019) derived a comprehensive formulation for estimating this sort of constant density bias.

      The addition of surface gravity data helps to constrain the solution when the number of muography stations is small. In the case of Fig. 3.5, where only one muography station is given, the gravity data contributes greatly to locating the high‐density lava block. However, the impact of the gravity data would be not so impressive when the target is covered by several muography detectors. According to the numerical simulation by Jourde et al. (2015), the addition of gravity data is only effective when the target is surveyed by one or two muography detectors; gravity data are almost useless when the target is sampled by more than two muography sites. However, significant improvement of the resolution is obtained in deeper regions which are not covered by muography paths, because a fraction of information brought by muography data is transferred to the deep regions coupled to gravity data (Jourde et al., 2015). As technology for particle detection improves, it will be easier to install multiple muography detectors surrounding the target volcano. If the density distribution of the mountain above the muography detectors is accurately determined from only muon tomography, the gravitational contribution can be straightforwardly calculated and removed for density distribution analysis of deeper parts of volcanoes. How does the volcanic conduit extend to the deep reservoir? Is it filled with solidified magma or vacant, thus complying with deformation? These questions could be addressed by the joint analysis. One such measurement is ongoing at Mount Omuro scoria cone, Izu Peninsula, Japan, where more than ten muography detectors made of emulsion films are installed around the volcano (Nagahara & Miyamoto, 2018).

Schematic illustration of 2D density map of Showa-Shinzan lava dome derived from muography data after noise reduction and without noise reduction.

      1 Ambrosino, F., Anastasio, A., Bross, A., Béné, S., Boivin, P., Bonechi, L., et al. (2015). Joint measurement of the atmospheric muon flux through the Puy de Dôme volcano with plastic scintillators and Resistive Plate Chambers detectors. Journal of Geophysical Research Solid Earth, 120, 7290–7307. https://doi.org/10.1002/2015JB011969

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