15:30 〜 15:45
[SVC36-07] Surface phenomena and hazards of explosive submarine eruptions revealed by a global dataset
★Invited Papers
キーワード：海底噴火、マグマ水蒸気爆発、津波、火砕密度流、データベース
Submarine volcanic eruptions can produce diverse surface phenomena and hazards that differ from those of eruptions on land, such as phreatomagmatic explosions, tsunamis, and pumice rafts. Understanding the causes and processes of these surface phenomena and hazards posed especially by large-scale explosive submarine eruptions is essential for disaster prevention and mitigation for volcanoes near or below sea level. In this presentation, first the surface phenomena and processes of noteworthy explosive submarine eruptions in recent years are summarized. Such an analysis of recent eruptions is useful to elucidate key phenomena and processes during submarine eruptions and to evaluate the types and effects of hazards. Then I constructed a global database of all known submarine eruptions and extracted their general characteristics. I focus on the relationship between the water depth and the occurrence of surface phenomena, such as explosivity, subaerial pyroclastic density currents (PDCs), and tsunamis. Database analysis showed that the number of explosive phenomena on the sea surface and tsunamis decreases dramatically where the vent is at depths deeper than 400 m, and that detection methods are almost entirely limited to seismoacoustic signals, pumice rafts, discolored water, and direct observation by on-site expeditions. The proportion of eruptions accompanied by PDCs over the sea surface is less than 11% of the total, although eruptions in shallow water are more likely to be accompanied by PDCs. The database analysis strengths our knowledge of hazardous phenomena such as phreatomagmatic explosions, high eruption plumes, and tsunamis, and also contributes to constraining phenomena during past historical eruptions and assessing future hazards at submarine volcanoes.