抄録
Infrared airbon surveys have been made on the Nishinoshima volcnao of Ogasawara Islands and its surrounding sea surface, on January 13, 1974 by “Nishihnoshima Research Group”. The submarine eruptions near Nishinoshima have been initiated from April 1973. On December 21, the new volcano has grown to an island larger than the old Nishinoshima. This island is about 700 m long, 250 m wide and about 50 m hight above sea level. This volcanic island was named Nishinoshima-shinto which means a new Nishinoshima. On January 13, 1974, two cinder-cones have been formed at the eastern and western parts of the new island. Volcanic activities were limitted to the eastern cinder-cone. The red hot lava was seen in the crater and lava was flowing out from the flank. Small eruptions of Strombolian type with 50～100 m high cinder ejections have been observed at intervals of one to two minutes. Thermal measurments were made by the “Infrared line-scanor Model DEI-1200” having an InSb sensor. A filter from 4.5 to 5.5μ wave length was employed and three different flight levels 300 m, 450 m, and 900 m were employed. In order to determine the thermal feature of the active crater, sea surface and volcanic island, we employed three temperature regions such as “high”, “low” and “intermediate” ones.
