Sakurajima Volcano Erupts in Japan: Largest Eruption in Decades Sends Ash Plume Thousands of Feet

reply to post by Thorneblood


um..MOVE!!!
ha ha

Originally posted by Nyiah
o.O I could have sworn the Phillipine & Pacific plates subduct under the Eurasian plate, not the other way around.

That is correct. Well sort of. The further subdivision of the North American and Eurasian Plates into the Okhotsk, Amur, and Yangtze microplates can confuse this issue, and is a more recent occurrence. For example, the Pacific plate is diving underneath the Okhotsk Plate, and the Okhotsk Plate itself only recently acquired that name, as geologists were able to see that it apparently existed through study. Formerly, it was part of the North American plate. Its very existence, or not, is the subject of scientific debate. But for the most part, it seems to be accepted as a microplate on its own. But then you have people like PuterMan who don't believe in tectonic plate theory at all, or only in part.

The arrows at the plate boundaries on both the plate maps in this thread indicate the direction of subduction. In other words, those arrows indicate which plate is diving under the other one. There is also another way of referring to them. In my example above, the Pacific Plate can also be called the subducted plate, and the Okhotsk Plate called the subducting plate, because it is the Okhotsk Plate that is subducting down underneath it the Pacific Plate.

There is also usually with many plate tectonic maps like this, a given rate of subduction in mm/year at the plate boundaries. That indicates how many mm per year the subducted plate travels past the interface point, as it is diving under the other plate.

Massive megathrust earthquakes can occur when the upper lip of the subducting plate gets pulled down with the subducted plate and reaches a breaking point when friction cannot hold it any longer. It springs back up violently, and if underwater, causes tsunamis.

At least that's the way I understand how it works. Anyway, yeah, Japan is probably one of the worst countries in the world in which to build nuclear reactors, because of its precarious position on several plate boundary junction points. It has one of the highest rates of seismicity anywhere.

Another curious, little known phenomena can occur too at these critical plate boundaries, and they believe this happened in the 2004 Sumatra Quake which caused that massive tsunami. It happens when a portion of that upper lip is weaker than the rest of the surrounding rock, and during the quake, a piece of it all of sudden rises up sharply, and higher than the rest of the uplift. This can cause a tsunami itself that is higher than the rest of the general tsunami. I believe it is called a splay fault, or something like that. In one report, a guy climbed up a tree on a hill to get away from it, and said the wave STILL went over his head. But he clung on for dear life and survived. Geologists determined that portion of the wave reached some 33 meters (or about 100 feet) high.

EDIT to answer questions below:

What are your thoughts and its eruption with the highest ever recorded ejection height of 3miles? And that in correlation to the plates which will reverberate to Fukushima?

1. Well sometimes volcanoes erupt bigger than last time. Sometimes they don't. It's one of the deep mysteries of volcanic systems that is not well understood- and mostly because there is a limit how far geologists can see what is really going on down there- way deep in the earth. Sometimes magmatic systems get extremely recharged from deep in the earth, and sometimes they only get partially recharged. This can have a drastic effect on the intensity of the eruptions, combined with a whole host of other influences- including magma composition, its related and particular degassing regiments, and the role of hydrothermal features at the time.

2. Volcanic eruptions usually produce limited amplitude seismicity, which can only propagate so far. In this case, I believe there is not, and could not be, any reasonable connection- because of sheer distance- between what is happening at that volcano, and what happens at Fukushima.

reply to post by TrueAmerican


So awesome you came and awesome you shared that clarification. But um, yeah, how about that volcano eh?

What are your thoughts and its eruption with the highest ever recorded ejection height of 3miles? And that in correlation to the plates which will reverberate to Fukushima?

Lastly, what are your thought these events triggering the worst imaginable disaster, Godzilla?

reply to post by Rosinitiate

This page may answer your questions
www.glgarcs.net...

reply to post by this_is_who_we_are


I see someone came in with the answer on that one.

Sakurajima is of course one of the 16/17 volcanoes in the world classified as always erupting.

The one to watch is Fuji-san, not Sakurajima.

reply to post by this_is_who_we_are


you forgot to mention that this volcano literally has erupted 500 times this year

Japan Today: Sakurajima volcano erupts for 500th time this year

sorry, no doom here

Originally posted by autopat51
one thing i'll say.
most of those cars plowing through that ash,
wont be running very long..learned that lesson from st. helens.

Very interesting comment autopat51, makes you wonder if some of those will show up in other parts of the World as second hand Jap imports. Its a big section of the car market here in NZ, I drive an imported Toyota Hiace myself, you get every little detail from the importers about where in Japan the vehicle came from.
I wonder how many ex 2011 Tsunami vehicles were shipped out?
Something I hope I remember to check next time I upgrade mine.

Mainichi

The amount of magma trapped within Sakurajima volcano here is near the level that was present before a huge 1914 eruption, say researchers.

The scientists say that although there are no signs of an immediate large eruption, people should be prepared for one in the future.

Sakurajima is one of the most active volcanoes in the world. Recorded history shows it having large eruptions in 764 A.D., from 1471 to 1476 A.D., from 1779 to 1782 A.D., and in 1914. The 1914 eruption was the worst one in Japan in the 20th century, killing 58 people and burning down 2,268 homes. The eruption emitted around 2.1 billion cubic meters of volcanic matter, around 10 times what spewed out of Mount Unzen in Nagasaki Prefecture from 1990 to 1995.

Following the 1914 eruption, the volcano exploded again in 1946, claiming the life of one person, and from 1955 to the present it has been in a continued period of volcanic activity. From 2006, the majority of volcanic activity has shifted from a crater near the summit to one on the east side, called the Showa crater, and there has been a steep rise in explosive eruptions, with 885 last year.

Thought i would add an update on this story.....the level of the magma seems to indicate something is coming for this area....wonder if it will actually blow its top instead of making noise.