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Title: 桜島火山・昭和火口で発生した噴煙のPIV解析
Other Titles: PIV Analysis of Ash Clouds Ejected from Showa Crater of Sakurajima Volcano
Authors: 石峯, 康浩  KAKEN_name
瀧本, 浩史  KAKEN_name
神田, 学  KAKEN_name
木下, 紀正  KAKEN_name
横尾, 亮彦  kyouindb  KAKEN_id  orcid (unconfirmed)
井口, 正人  kyouindb  KAKEN_id
Author's alias: ISHIMINE, Yasuhiro
KANDA, Manabu
YOKOO, Akihiko
IGUCHI, Masato
Keywords: 火山噴火
volcanic eruption
ash clouds
discharge speed
video analysis
Issue Date: 1-Jun-2009
Publisher: 京都大学防災研究所
Journal title: 京都大学防災研究所年報. B = Disaster Prevention Research Institute Annuals. B
Volume: 52
Issue: B
Start page: 319
End page: 322
Abstract: 桜島火山・昭和火口の噴火活動で発生した噴煙を撮影した映像にPIV法を適用し,噴煙の噴出速度を求めた。流れの中に混入した浮遊粒子をトレーサーとして用いるオーソドックスなPIV法とは異なり,本研究では,乱流渦の濃淡をトレーサーとして,加賀ら(1994)が提唱した逐次棄却法を適用した。その結果,視界が良い晴天の日中時に撮影された映像においては,噴煙の噴出速度を適切に抽出することに成功した。例えば,2007年5月24日午前10時19分の噴火では,噴火開始後5秒間の火口直上における最高速度の平均値は約83 m/sと,同じ5秒間での噴煙最高点の平均上昇速度(約31 m/s)の約2.7倍に達していたことが分かった。
The discharge speeds of ash clouds ejected from Showa crater of Sakurajimavolcano in Kagoshima, Japan, were obtained by applying the Particle ImageVelocimetry (PIV) method, which is a computer-aided image analysistechnique, to close-up video images recorded during recent eruptions. Thespatial patterns of turbulent eddies were used as tracers instead ofsuspended particles to yield velocity distributions with SuccessiveAbandonment Method proposed by Kaga et al. (1994). The discharge speeds of ash clouds were successfully identified for the video images with a clear view in daytime. This study revealed that the discharge speed immediately above Showa crater was about 83 m/s during the first five seconds on average for the ash cloud on 24 May 2007 while the average spreading speed of the uppermost part of the same ash cloud was about 31 m/s.
Appears in Collections:No.52 B

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