論文

査読有り
2018年4月1日

Distribution and mass of tephra-fall deposits from volcanic eruptions of Sakurajima Volcano based on posteruption surveys

Bulletin of Volcanology
  • Masayuki Oishi
  • ,
  • Kuniaki Nishiki
  • ,
  • Nobuo Geshi
  • ,
  • Ryuta Furukawa
  • ,
  • Yoshihiro Ishizuka
  • ,
  • Teruki Oikawa
  • ,
  • Takahiro Yamamoto
  • ,
  • Futoshi Nanayama
  • ,
  • Akiko Tanaka
  • ,
  • Akinari Hirota
  • ,
  • Takahiro Miwa
  • ,
  • Yasuo Miyabuchi

80
4
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1007/s00445-018-1215-3
出版者・発行元
Springer Verlag

We estimate the total mass of ash fall deposits for individual eruptions of Sakurajima Volcano, southwest Japan based on distribution maps of the tephra fallout. Five ash-sampling campaigns were performed between 2011 and 2015, during which time Sakurajima continued to emit ash from frequent Vulcanian explosions. During each survey, between 29 and 53 ash samplers were installed in a zone 2.2–43 km downwind of the source crater. Total masses of erupted tephra were estimated using several empirical methods based on the relationship between the area surrounded by a given isopleth and the thickness of ash fall within each isopleth. We obtained 70–40,520 t (4.7 × 10−8–2.7 × 10−5-km3 DRE) as the minimum estimated mass of erupted materials for each eruption period. The minimum erupted mass of tephra produced during the recorded events was calculated as being 890–5140 t (5.9 × 10−7–3.6 × 10−6-km3 DRE). This calculation was based on the total mass of tephra collected during any one eruptive period and the number of eruptions during that period. These values may thus also include the contribution of continuous weak ash emissions before and after prominent eruptions. We analyzed the meteorological effects on ash fall distribution patterns and concluded that the width of distribution area of an ash fall is strongly controlled by the near-ground wind speed. The direction of the isopleth axis for larger masses is affected by the local wind direction at ground level. Furthermore, the wind direction influences the direction of the isopleth axes more at higher altitude. While a second maximum of ash fall can appear, the influence of rain might only affect the finer particles in distal areas.

リンク情報
DOI
https://doi.org/10.1007/s00445-018-1215-3
URL
http://link.springer.com/article/10.1007/s00445-018-1215-3/fulltext.html
URL
http://link.springer.com/content/pdf/10.1007/s00445-018-1215-3.pdf

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