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400 explosions and counting!

November 7, 2009

Many thanks to Wes for passing on information that “explosive eruptions” at Sakurajima passed the 400 mark earlier this week: should Kagoshima start preparing for the big one?!

As the article states, this year has seen the greatest number of explosions for 24 years and activity is very similar to that which preceded the large Showa eruption in 1946. That time lava spewed out from the Showa crater covering much of the eastern flank of the volcano. If this were to happen again, well dear visitors of Kagoshima, you’re in for a treat! Despite damage to local agriculture – and there is a farmer who currently grows broad beans in that vicinity – the prospect of viewing live lava flows would provide a huge boost to local tourism.

However, if explosivity was to increase…

Sakurajima from space (NASA Earth Observatory, via the Eruptions blog)

A recent image of Sakurajima from space (NASA Earth Observatory, via the Eruptions blog). Spot the ash plume in the centre, although much of the haze is from the Asian continent.

Elsewhere, JMA have also published a nice report on their website (in Japanese). The ever-changing colour of the lake at Naka-Dake (中岳), Mount Aso (阿蘇山) has always lured volcanologists, but recent pictures also show a red glow to the side of the crater:

Naka-dake (中岳) crater and area of red glow (from JMA)

Naka-dake crater, Aso and area of red glow (from JMA)

Red glow at Naka-Dake (JMA)

Red glow at side of Naka-Dake crater (from JMA)

What this means I do not know, but there are around nine craters up at Naka-dake and the magma source has shifted activity from one to the next over the years. One outrageous suggestion could be that this is the start of a new shift? We shall have to see – for now the activity remains ‘normal’ and no doubt the glow will provide an extra attraction for the bus tour groups that continue to ride the horrible tarmac all the way to the top.

Ikimashou…

October 25, 2009
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The Mountain Man

October 18, 2009

"Volcano Asama" by Umetaro Azechi (image: Fine Arts Museums of San Francisco)

"Mount Asama" (1953) by Umetaro Azechi (image: Fine Arts Museums of San Francisco)

I am probably committing a huge infringement of copyright laws, but it’s nice to come across artwork of Japanese volcanoes that is not in the guise of traditional woodblock images of Mt. Fuji – as wonderful as they are.

I came across Umetaro Azechi (1902-1999) while exploring the British Museum a few months ago, where framed in the corner of the ‘Japan Room’ was a woodcut of his, titled Mountain Man. Simple, yet jumping out at you, the mountain man was defiant – perhaps a Japanese male refusing to go to the office; instead heading to where the real action is. I couldn’t find the same image online, but here is an equally simple print of Mt. Asama, almost South American in appearance. It could be the Columbian Andes rather than a volcano on the Kanto plain!

You can read more about Azechi – a keen mountain lover – here, a site which also includes a great representation of the winter mountaineer.

Satsuma-Fuji

October 11, 2009
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Sunrise at Kaimon-dake (開聞岳): possibly the finest sunrise I have ever witnessed.

As you may be able to tell, Kaimon is commonly referred to as the “Mount Fuji of Satsuma” (where Satsuma was the old province that now forms a large part of the present day prefecture of Kagoshima). The hike up is a reasonable circular path starting around sea-level and finishing at the 924m summit with clear-weather views towards the smoking peaks of Sakurajima to the north and Satsuma-Iojima to the south. However, for many volcano lovers the mountain’s shape is enough to wetten the appetite and it certainly has my vote as the best Fuji-San imitation.

What’s yours?

Mt. Asama and cosmic rays

October 6, 2009
Active vent of Mt. Asama (photo: Tokyo University)

The active vent of Mt. Asama (photo: Tokyo University)

I love the ingenuity of Japanese volcanologists.

After drilling into Mt. Unzen and sending unmanned machines in to build sabo dams, the New Scientist reports this week that scientists from Tokyo University have demonstrated a technique to measure the mass of material inside a volcano using cosmic radiation. They have “looked” into Mt Asama!

By measuring very complicated-sounding particles called muons, which are formed when cosmic rays interact with our atmosphere, the Tokyo scientists have been able to measure how they pass through the solid Earth. Passing through rocks of different densities the muons are absorbed at different rates, thus under a volcano one can locate molten magma. Understand?!

Essentially, they have been able to “scan” the volcano and come up with a picture of what its inner structure might look like – analogous to an MRI scan to view an unborn baby, say. At Asama volcano, they were able to do this before and after an eruption (in February earlier this year) and calculate just how much material was erupted. The answer? Over 30,000 tonnes – puny in terms of big eruptions, but an accurate figure compared to estimates of total ash fall.

This now means that volcanologists may be able to look at the insides of a volcano like never before: an obvious benefit for monitoring activity. One day they might even be able to see “shifting magma” – a curious insight into the world below.

When it rains, it pours

October 5, 2009

More ash in Kagoshima...

More ash in Kagoshima...

Active Japan

October 1, 2009

Unfortunately Japanese volcanoes only get a brief mention in the SI/USGS Weekly Activity Reports, but here is the current status of the most active volcanoes in the country as of September 27th. Below are the English translations of the volcano names and you will see that Sakurajima is the only volcano with an elevated alert status of level 3: an explosive summer appears to be continuing into autumn – so far today (1st Oct.) there have been 14 explosions!

Volcanic Alert Levels (from JMA; click for more in Japanese)

Volcanic Alert Levels (from JMA; click for more in Japanese)

浅間山, Asama: level 2.

三宅島, Miyakejima: level 2.

桜島, Sakurajima: level 3.

薩摩硫黄島, Satsuma-Iojima: level 2.

口永良部島, Kuchinoerabujima: level 2.

諏訪瀬島, Suwanosejima: level 2.


Ash from Sakurajima on a van (photo: flickr user africadunc)

Ash from Sakurajima on a van (photo: flickr user africadunc)

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