Air inspection of Asama Volcano (1 October 2004)

Helicopter of Nagano Police, Shinshu
Clear sky with southerly wind
During 09:30 to 10:20 by Yoshimoto and Iijima (JMA-Karuizawa)
During 10:30-11:00 by Nakagawa (JMA-Karuizawa) and Matsuda (JMA)

Smoke is relativey weak, and drifted to the north. New vent of about 70 km diameter and about 40 m depth was formed on the center of the lava cake inside the summit (Kamayama) crater,
which was observed on 16 and 17 September by SAR image of GSI and photographs of the Yomiuri Shimbun, respectively. From the eastern rim of the vent, a crack of incandescence was observed, from which jet of volcanic gas was itenrmittently issued. Surface winkles on the lava cake that were observed on 17 September, were not clear due to coverage of new eruption products (ash and volcanic blocks) of the 23 and 29 eruptions. The highest temperature measured with the infrared camera by JMA was 517 deg C.

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Photo 1: 09:47, SW of the crater; smoke sometimes separted into two lines.
Photo 2: 09:54, same the above
Photo 3: 09:49, vent of 70 m across and about 40 m deep is a little left of the center.
Photo 4: 10:07, close-up view of newly-formed vent. Lava cake surface is covered with lava blocks of ash issued from the vent. Red arrow is a crack of strong gas-jetting.
Photo 5: 09:55, gas jetting from crack nearby the newly-fromed vent.
Photo 6: 09:59,
lava blocks scattered on the crater floor, probably by the 23 or 29 September eruptions.
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