熔岩喷发

• 作 者: 申童
• 出 处: 中华少年(DK少年百科)
• 发表日期: 2009年06期
• 关键词: 熔岩流 夏威夷群岛 坡度平缓 火山灰云 火山带 露出水面 海底火山 夏威夷岛 枕状熔岩 主图

在剧烈的喷发中,爆发的火山会毁坏土地,并且把炽热的火山灰云抛入天空。但另一种火山爆发却很平静,只是从地幔深处涌出流动和滚烫的岩浆。它们喷出的熔岩会冷却成一种深色的玄武岩,所以又称做玄武岩火山。这种火山经常活动,所以内部不会累积巨大的压力,反而会向上冒出,形成熔岩喷泉,且熔岩向四周溢流。经过一段时间后,这些溢流熔岩堆积成广大且坡度平缓的山。冰岛群岛和夏威夷群岛就是这么形成的。当熔岩流扩向海里时,火山岛会随着变大。海底火山如果增大而露出水面就形成新的岛屿。

In a violent eruption, the eruption of the volcano can destroy the land and throw the hot volcanic ash cloud into the sky. But another eruption was calm, except that the flow and hot magma gushed from the depths of the mantle. They emit the lava will be cooled into a dark basalt, so called basalt volcano. The volcano, which is constantly active, does not accumulate tremendous pressure on the interior, but instead rises upwards to form a lava fountain that overflows all around. Over time, these overflow lava stacked into a broad and gentle slope of the mountain. This is how the Icelandic and Hawaiian islands formed. When the lava flows into the sea, the volcano island will become larger. Submarine volcanoes increase if exposed to the surface of the water to form a new island.