アイスランドの噴火、６か月に　ここ５０年で最長

【ファグラダールスフィヤットルＡＦＰ＝時事】アイスランドの首都レイキャビク近くで今年３月に始まった噴火は、１９日で継続期間が半年となり、同国で発生した噴火としてはここおよそ５０年で最長となった。（写真はアイスランド南西部ファグラダールスフィヤットル山近くの谷に流れ込む溶岩）
　レイキャビク南西のレイキャネース半島のファグラダールスフィヤットル山近くの亀裂から、最初に溶岩が噴き出したのは３月１９日の午後。以降、アイスランド観光局によるとこれまでに３０万人の見物客が訪れた。
　火山学者のソルバルドル・トールダルソン氏は、「６か月はそこそこ長い」と語った。
　これまで流れ出た溶岩は約１億４３００万立方メートルに及ぶ。
　しかし、実はこの量は比較的少なく、過去２３０年で最大だったホルフロインの噴火で流れ出た玄武岩質溶岩の、わずか１０分の１にも満たない。
　アイスランドでこれまでに観測された噴火の最長記録は、５０年以上前に同国南部沖に浮かぶスルツェイ島で発生した噴火で、１９６３年１１月～６７年６月の４年近く続いた。
　アイスランド大学の地球科学研究所によると、現在も噴火口１か所で活動が続いている。この噴火口は３３４メートルで、周辺地域の最高峰からわずか数十メートルに位置する。
　噴火活動が近いうちに衰退する兆候はなく、地球科学研究所のハルドル・ギアソン氏は「どのマグマだまりにも十分なマグマがあるとみられる。噴火は長く続く可能性がある」と述べた。【翻訳編集ＡＦＰＢＢＮｅｗｓ】

〔ＡＦＰ＝時事〕（2021/09/21-10:45）

It will be six months on Sunday that the volcanic eruption currently mesmerising spectators near Reykjavik first began, making it the longest Iceland has witnessed in more than 50 years.
The first lava began spewing out of a fissure close to Mount Fagradalsfjall on the evening of March 19 on the Reykjanes peninsula to the southwest of Reykjavik.
And the ensuing spectacle -- ranging from just a slow trickle of lava at times to more dramatic geyser-like spurts of rocks and stones at others -- has become a major tourist attraction, drawing 300,000 visitors so far, according to the Iceland Tourist Board.
Iceland's sixth volcanic eruption in 20 years is already longer than the preceding one in Holuhraun, in the centre-east of the island, which lasted from the end of August 2014 until the end of February 2015.
Six months is a reasonably long eruption, volcanologist Thorvaldur Thordarson told AFP.
The lava field that has formed this time has been christened Fagradalshraun -- which can be translated as beautiful valley of lava -- and takes its name from nearby Mount Fagradalsfjall.
Almost 143 million cubic metres of lava have been spewed out so far.
But that is actually comparatively small, representing just under a tenth of the volume of the Holuhraun eruption, which spewed out the biggest basalt lava flow in Iceland in 230 years.
The latest eruption is special in the sense that it has kept a relatively steady outflow, so it's been going quite strong, said Halldor Geirsson, a geophysicist at the Institute of Earth Science.
The usual behaviour that we know from volcanoes in Iceland is that they start really active and pour out lava, and then the outflow sort of decreases over time until it stops, he said.
Iceland's longest-ever eruption took place more than 50 years ago -- on Surtsey island just off the southern coast -- and lasted nearly four years, from November 1963 until June 1967.
- No end in sight -
After subsiding for nine days, the lava reappeared at Fagradalshraun in early September, occasionally spurting red-hot from the crater and accompanied by a powerful plume of smoke.
It also accumulated in fiery tunnels beneath the solidified surface, forming pockets that eventually gave way and unfurled like a wave onto the shore.
The real number of visitors trekking to the rough hills to view the spectacle is probably even higher than the estimated 300,000, as the first counter installed on the paths leading to the site was only set up five days after the eruption.
In the first month, 10 fissures opened up, forming seven small craters, of which only two are still visible.
Only one crater is still active, measuring 334 metres (1,100 feet), according to the Institute of Earth Science, just a few dozen metres short of the highest peak in the surrounding area.
Nevertheless, the volcano is showing no sign of fading anytime soon.
There seems to be still enough magma from whatever reservoir the eruption is tapping. So it could go on for a long time, said Geirsson.