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Radiographic visualization of magma dynamics in an erupting volcano.

Tanaka HK, Kusagaya T, Shinohara H - Nat Commun (2014)

Bottom Line: Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed.In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending.We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

View Article: PubMed Central - PubMed

Affiliation: Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.

ABSTRACT
Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography) with dynamic radiographic imaging. Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed. In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending. We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

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Experimental set-up of current muographic observation system.(a) A profile of residual gravity and topography sliced along the dotted line in (b) is derived from Bouguer anomalies of an assumed density of 2.0 g cm−3 and trend removal of upward-continuation of 500 m (ref. 19) based on the gravity data set obtained for the published map. (b) The topographic map of Satsuma–Iwojima volcano shows the location of the muon detector (indicated by Mu). A topographic profile along the A–B line was created to support muographic images.(c) A schematic view of the detector was used for the present observation. It consists of five lead plates supported by stainless steel plates and six layers of scintillation PSPs. Scale bar 1 m. The inset shows the layout of the PSP consists of adjacent scintillator strips, which together form a segmented plane. (d) Close-up map of the summit area of the cone in the box on the map labelled as (b). This enlarged map shows newly created inner crater between 1997 and 2003 (blue, green and orange lines). The grey line on the map corresponds to the A–B line shown in (b).
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f1: Experimental set-up of current muographic observation system.(a) A profile of residual gravity and topography sliced along the dotted line in (b) is derived from Bouguer anomalies of an assumed density of 2.0 g cm−3 and trend removal of upward-continuation of 500 m (ref. 19) based on the gravity data set obtained for the published map. (b) The topographic map of Satsuma–Iwojima volcano shows the location of the muon detector (indicated by Mu). A topographic profile along the A–B line was created to support muographic images.(c) A schematic view of the detector was used for the present observation. It consists of five lead plates supported by stainless steel plates and six layers of scintillation PSPs. Scale bar 1 m. The inset shows the layout of the PSP consists of adjacent scintillator strips, which together form a segmented plane. (d) Close-up map of the summit area of the cone in the box on the map labelled as (b). This enlarged map shows newly created inner crater between 1997 and 2003 (blue, green and orange lines). The grey line on the map corresponds to the A–B line shown in (b).

Mentions: We developed a muon detector with the lowest noise levels to visualize and analyse magma movements and modification patterns in Satsuma–Iwojima volcano, Japan. Satsuma–Iwojima volcano (Fig. 1a), composed of cooled thick lava flows and corresponding collapsed deposits, discharges a large amount of volcanic gases with SO2 flux of 500–1,000 t day−1 (ref. 21). SO2 flux and volcanic gas composition have been almost constant for at least the last 30 years, and this rate has likely been constant for >100 years (ref. 21). A new vent formed in 1997 and by 2003 had enlarged to become an internal crater (Fig. 1d). On 4 June 2013, the eruption alert level had risen from level 1 (signs of volcano unrest) to level 2 (minor eruptive activity). On 13 June, it was detected that the vent size increased. The eruption sequence of 2013 Satsuma–Iwojima eruption is shown in Table 1. The muon detector was placed ~1.4 km from the summit crater (Mu in Fig. 1a) on 14 June 2013.


Radiographic visualization of magma dynamics in an erupting volcano.

Tanaka HK, Kusagaya T, Shinohara H - Nat Commun (2014)

Experimental set-up of current muographic observation system.(a) A profile of residual gravity and topography sliced along the dotted line in (b) is derived from Bouguer anomalies of an assumed density of 2.0 g cm−3 and trend removal of upward-continuation of 500 m (ref. 19) based on the gravity data set obtained for the published map. (b) The topographic map of Satsuma–Iwojima volcano shows the location of the muon detector (indicated by Mu). A topographic profile along the A–B line was created to support muographic images.(c) A schematic view of the detector was used for the present observation. It consists of five lead plates supported by stainless steel plates and six layers of scintillation PSPs. Scale bar 1 m. The inset shows the layout of the PSP consists of adjacent scintillator strips, which together form a segmented plane. (d) Close-up map of the summit area of the cone in the box on the map labelled as (b). This enlarged map shows newly created inner crater between 1997 and 2003 (blue, green and orange lines). The grey line on the map corresponds to the A–B line shown in (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3959196&req=5

f1: Experimental set-up of current muographic observation system.(a) A profile of residual gravity and topography sliced along the dotted line in (b) is derived from Bouguer anomalies of an assumed density of 2.0 g cm−3 and trend removal of upward-continuation of 500 m (ref. 19) based on the gravity data set obtained for the published map. (b) The topographic map of Satsuma–Iwojima volcano shows the location of the muon detector (indicated by Mu). A topographic profile along the A–B line was created to support muographic images.(c) A schematic view of the detector was used for the present observation. It consists of five lead plates supported by stainless steel plates and six layers of scintillation PSPs. Scale bar 1 m. The inset shows the layout of the PSP consists of adjacent scintillator strips, which together form a segmented plane. (d) Close-up map of the summit area of the cone in the box on the map labelled as (b). This enlarged map shows newly created inner crater between 1997 and 2003 (blue, green and orange lines). The grey line on the map corresponds to the A–B line shown in (b).
Mentions: We developed a muon detector with the lowest noise levels to visualize and analyse magma movements and modification patterns in Satsuma–Iwojima volcano, Japan. Satsuma–Iwojima volcano (Fig. 1a), composed of cooled thick lava flows and corresponding collapsed deposits, discharges a large amount of volcanic gases with SO2 flux of 500–1,000 t day−1 (ref. 21). SO2 flux and volcanic gas composition have been almost constant for at least the last 30 years, and this rate has likely been constant for >100 years (ref. 21). A new vent formed in 1997 and by 2003 had enlarged to become an internal crater (Fig. 1d). On 4 June 2013, the eruption alert level had risen from level 1 (signs of volcano unrest) to level 2 (minor eruptive activity). On 13 June, it was detected that the vent size increased. The eruption sequence of 2013 Satsuma–Iwojima eruption is shown in Table 1. The muon detector was placed ~1.4 km from the summit crater (Mu in Fig. 1a) on 14 June 2013.

Bottom Line: Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed.In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending.We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

View Article: PubMed Central - PubMed

Affiliation: Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.

ABSTRACT
Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography) with dynamic radiographic imaging. Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed. In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending. We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

Show MeSH
Related in: MedlinePlus