Volcanic disaster

Japanese: 火山災害 - かざんさいがい

Disasters caused by volcanic activity. They are caused by mountain collapses caused by eruptions and volcanic ejecta (lava, volcanic gas, pyroclastic material) spewed onto the ground. In particular, large cinders with a diameter of 20 to 30 cm or more that fly in a ballistic trajectory with little effect from the wind, pyroclastic flows that flow down slopes at high speeds while convecting high-temperature volcanic gas and pyroclastic material, snowmelt-type volcanic mudflows that melt glaciers and snow near the summit and carry soil and sand, and tsunamis caused by eruptions at submarine volcanoes or near the sea area are life-threatening because there is no time to evacuate. On the other hand, lava flows tend to move slowly, and there are relatively few cases of loss of life. Small cinders and volcanic ash are carried by the wind and spread widely, causing damage to transportation such as aircraft and agricultural crops. Inhaling toxic components from volcanic gases can be harmful to health, and when sulfur-containing gas enters the stratosphere, it can cause abnormal weather such as "volcanic winter." Even if the eruption calms down, rain will cause debris flows, which are caused by volcanic material moving. The Japan Meteorological Agency issues information about volcanic activity, such as eruption warnings and forecasts, ash fall forecasts, and volcanic gas forecasts, and calls for caution.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

火山活動によって引き起こされる災害。噴火に伴う山体崩壊や，地上に噴出した火山噴出物（溶岩，火山ガス，火山砕屑物）によってもたらされる。特に，風の影響をほとんど受けずに弾道を描いて飛翔する直径 20～30cm以上の大きな噴石，高温の火山ガスと火山砕屑物が対流しながら高速で斜面を降下する火砕流，山頂付近の氷河や雪が溶けて土砂を巻き込んで流れる融雪型火山泥流，海底火山や海域付近での噴火が招く津波は避難のための時間的猶予がなく，生命の危険につながる。一方，溶岩流は速度の遅いものが多く，人命が失われる事例は比較的少ない。小さな噴石や火山灰は風に乗って広く拡散し，航空機などの交通機関や農作物に被害を与える。火山ガスは有毒な成分を吸引すると健康被害を及ぼすほか，硫黄分を含んだガスが成層圏に入ると「火山の冬」などの異常気象を引き起こすこともある。噴火が沈静化しても，雨によって火山噴出物が流動する土石流は継続する。気象庁は火山活動に関する情報として，噴火警報・予報，降灰予報，火山ガス予報などを発表し，警戒を呼びかけている。

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