[SVC38-P18] Present condition of submarged volcano, Teishi Knoll, off Ito, Eastern Izu Peninsula
Keywords:Teishi Knoll, Submerged volcano, Activity, Chemical flux, Heat flow
In Japan there are confirmed 110 active volcanoes, 12 volcanoes of them are located below sea surface. Such submerged volcanoes have not been observed continuously due to its difficulty by visual observation, therefore, those volcanoes have not ranked according their activity by Japan Meteorological Agency. Therefore, we started observation of Teishi volcano in December, 2017, for evaluation whether active magma supply is still continuing or the intrusive magma causing of 1989 eruption is just cooling. Geochemical (water chemistry) and geophysical (heat-flow) observation has been done using training vessels of TUMSAT every half year.
We have not accumulated enough data yet, measurements of geothermal gradient were performed every time. For calculation of the heat-flow it is required the temperature record of the bottom water, so we started long-term temperature observation on the seafloor from the last December. On the other hand, chemistry of the bottom water in the crater showed slight positive anomaly of dissolved inorganic carbon and significant positive anomaly of manganese relative to the bottom water obtained from outside of the crater. Those chemical anomalies suggest that any thermal activity is still alive in the volcano.