The analyses of the vulcanian eruption products based on combination of the IKONOS high-resolution satellite imagery and the field survey:

Sakagami Masayuki, Sasaki Hisashi, Miyake Yasuyuki, Mukoyama Sakae

doi:10.5575/geosoc.2011.0012

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IKONOS高分解能衛星画像と現地踏査を併用したブルカノ式噴火噴出物の解析：
IKONOS高分解能衛星画像と現地踏査を併用したブルカノ式噴火噴出物の解析 : 浅間火山2004年9月1日噴火を例に
IKONOS コウブンカイノウエイセイガゾウトゲンチトウサオヘイヨウシタブルカノシキフンカフンシュツブツノカイセキ : アサマカザン 2004ネン 9ガツ 1ニチフンカオレイニ
An example of the eruption of the Asama volcano on September 1st in 2004
浅間火山2004年9月1日噴火を例に

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The Asama volcano erupted on 1 September 2004, followed by several more eruptions during the period from September to December 2004. In the proximal area, particularly on the western side of the crater, the distribution and details of ejecta from the September 1 eruption have not been well studied. The purpose of this study is to investigate the ejecta from this area, and to obtain information concerning the juvenile magma of one eruption. Sasaki and Mukoyama (2006) presented a distribution map of the impact craters of the September 1 eruption, using IKONOS high-resolution satellite imagery; this imagery is partially effective for determining the distribution of ejecta from the eruption. However, ejecta in deep forests are not detectable by IKONOS imagery, and the rock types of the ejecta cannot be ascertained from imagery alone. Therefore, we collected field observations on the distribution of ejecta, to evaluate the effectiveness of IKONOS imagery data. After examining 130 impact craters identified by Sasaki and Mukoyama (2006), we determined that more than 100 of the impact craters (of various sizes) had been formed by impacts of massive and/or altered accessory blocks. At the other 30 spots, we discovered three juvenile breadcrust bombs. Moreover, we discovered 24 bombs at sites not detected by the IKONOS imagery. These results indicate that a combination of satellite imagery and field surveys is required to obtain precise distributions and details of volcanic ejecta. The water contents in the glass rinds of the 22 breadcrust bombs were from 0.49 to 0.86 wt.%. Calculations of magma depth on the basis of these water contents indicate that the magma column was at least 180 m high.

Journal

The Journal of the Geological Society of Japan

The Journal of the Geological Society of Japan 117 (12), 671-685, 2011-12-15

The Geological Society of Japan

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