平成12年有珠山噴火リモート・センシング:昭和52年噴火活動との比較など

Abstract

2000年3月に有珠山が23年ぶりに噴火し、地形の変化、降灰分布、地表面温度の分布と変化について、1977年の噴火についての解析結果と今回の活動の結果を比較した。航空写真を相互標定、絶対標定し、第1火口群周辺では放射状に周囲に発散するパターンの水平変位を認めた。高さ方向の変位は最大で20mであった。第2火口群周辺では、南側は南に、北側は北に動いた。隆起量は13m程度であった。降灰量が多いのは火口付近と洞爺湖温泉街背後の山地で約400ha、中程度は周縁部で約400ha、軽微な箇所はその周縁部で1,000haであった。温度が高いのは火口や断層帯で、第2火口群周辺が特に高かった。

Mt. Usu erupted in March 2000, 23 years after the last eruption. The analysis results of geographical deformation, distribution of ash fall, and surface temperature distribution from 1977 were compared with those of the results from the new eruption . Aerial photographs were assayed both relatively and absolutely. Around the first crater group, horizontal displacement was found to have been diverged radially. The maximum vertical shift was 20 m. Around the second crater group, the south side shifted to south and the north side shifted to north. The rising height was about 13 m. The amount of ash fall was the largest in the 400 ha area around the craters and in the mountains behind Lake Tohya spa town. Then, the periphery area of 400 ha around those areas was at the medium level, and the ash fall was the smallest in the 1,000 ha periphery area of the middle area. The temperature was the highest at the craters and at the fault zone, especially around the second crater group.