[Mongoose]

There were also reports of an eruption in Indonesia.  It's not a good time to be living on the Ring of Fire.

[Flipside]

There's also an increase in Volcanic activity in Hawaii.

http://www.earthweek.com/2011/ew110311/ew110311d.html

Thing is though, this was being predicted to be on the cards when I was younger. It's just part of a cycle that the ring of fire goes through.

[DCFan]

How many people died?

[watsisname]

There were also reports of an eruption in Indonesia.  It's not a good time to be living on the Ring of Fire.

I don't think there's ever a good time to be living on the Ring of Fire... that is to say within close proximity of an active volcano.

Both eruptions took place at volcanoes that have seen lots of activity in the recent past, and I remain skeptical of any real causal link between the quake and the eruptions.  Especially in the case of Hawaii, since it's a hotspot smack in the middle of the Pacific Plate and thus not related to the fault system that caused the Japanese quake.

[Flipside]

Well, Earthquakes send shockwaves across and, more importantly, through the planet, but, yes, I'm inclined to agree to no direct causal link (Since that Hawaii episode happened some time before the quake, on March 5th), but tectonic activity tends to go through cycles much like anything else, and I remember being in the Natural History museum at 16 and being told the Earth was close to entering a new period of higher tectonic activity, but that this was nothing to get overly concerned about on the larger scale (though obviously on the 'smaller' per-event scale, events like this are obviously another matter).

[General Battuta]

it burns burns burns
that burning ring of fire

[Mongoose]

There were also reports of an eruption in Indonesia.  It's not a good time to be living on the Ring of Fire.

I don't think there's ever a good time to be living on the Ring of Fire... that is to say within close proximity of an active volcano.

Both eruptions took place at volcanoes that have seen lots of activity in the recent past, and I remain skeptical of any real causal link between the quake and the eruptions.  Especially in the case of Hawaii, since it's a hotspot smack in the middle of the Pacific Plate and thus not related to the fault system that caused the Japanese quake.

See, I've also heard scientists state that it's difficult to draw causal links even between recent tectonic events in the same area of the world, but something about that has always bothered me.  When an earthquake occurs, continental plates jerk or shift along a particular fault line.  So if movement occurs to release pressure along one edge of a tectonic plate, wouldn't it follow that some other border of that plate might be put under greater pressure as a result, possibly leading to tectonic activity along another fault line?  Granted, I'm not saying that something like the Hawaii eruption is related, but when you look at something like the Christchurch earthquake...things get a bit murkier.

[watsisname]

Oh I don't doubt one bit that earthquakes themselves can be linked in such a way, especially if they are occurring on the same plate boundary.  Come to think of it I do recall seeing research that suggested how an earthquake at one location on a fault would increase or decrease stresses in other areas, in some cases going so far as to cause a linear progression of earthquakes, one by one, down the fault line.  I can't remember offhand where I saw this though.

I'm just skeptical of earthquakes having any profound effect on volcanic activity, particularly over large distances.  I think that the recent volcanic activity taking place after the March 11th earthquake is simply coincidence, or perhaps its due to some cyclic pattern in how the "ring of fire" goes off.  Certainly the Christchurch quake may provide some support for the latter theory.

[Bobboau]

well, I don't think it is inconceivable that some sort of phenomena exists that results in increased magma pressure under a plate that triggers volcanism and earth quakes. that said 'not inconceivable' != 'likely'

[Klaustrophobia]

the most geology i had was in high school "earth science" class, but i don't think it's too much of a strech that earthquakes and volcanic activity can be related, even over great distances.  the shift in the plate that caused the earthquake could also potentially open up a gap and release magma.  now hawaii, being smack dab in the middle of the pacific plate, wouldn't really fit this idea.

[Kosh]

well, I don't think it is inconceivable that some sort of phenomena exists that results in increased magma pressure under a plate that triggers volcanism and earth quakes. that said 'not inconceivable' != 'likely'

Actually it does lead to volcanism, though usually not immediately. The ocean plate subducts and gets melted, creating more magma which in turn increases the magma pressure.

[Bobboau]

well that is clearly not something that would link the Hawaii volcanism and the west pacific earthquakes.

[Androgeos Exeunt]

Another explosion has occurred at the Fukushima plant.

http://www.bbc.co.uk/news/world-asia-pacific-12729138

[Flipside]

http://www.bbc.co.uk/news/world-asia-pacific-12733393

Not good, Not good at all.... Looks like the reactor rods has been exposed, causing a meltdown alert....

[perihelion]

So, how long does it take for the radioactivity in the fuel rods to die down enough that active cooling (pumping) is no longer needed?  A couple weeks?

[Black Wolf]

A couple of billion years. They're made of uranium.

[perihelion]

   I really don't think my question was worded that poorly, but to clarify:  How long must active cooling be maintained before the radioactivity from short-term daughter reactions has died down enough that there is no longer a risk of the fuel rods melting?  The fission reaction has been effectively killed, but there is still a lot of short-term radioactive decay going on from fission by-products that will last for "a little while," i.e. days and weeks.  We are not talking million-year plus half lives here.  These are extremely fast decaying byproducts that, while the reactor is operating, are present in relatively steady amounts.  They form once the reaction is brought online, then they eventually reach a steady-state maximum as the rate of their formation and rate of decay find an equilibrium.  Now that the fission reaction is dead, the rate at which these byproducts are are being made should be... I don't know if it would be zero, but it would be several orders of magnitude lower than the rate of decay.  So those byproducts will be present and accounting for most of the heat still being produced until enough has decayed that the heat output is so low that natural convection and radiant heat transfer can prevent melting.

I am probably not using the correct terms (or using them incorrectly) since this is not my field, but I think I'm asking the right questions?  Isn't this the one that really matters?  If they can find a way to keep the fuel rods from getting too hot for a few more days, enough of the high-rate radioactives will have been decayed that the problem will fix itself?

[Flipside]

It doesn't take long to stabilise so long as there is a supply of coolant flowing over the rods. They have managed to get some sort of system in place, so hopefully that will hold until a more permanent system can be put in place.

The rods themselves will just go on reacting regardless. The danger of the exposed core is that the rods will get so hot they will melt through the bottom of the reactor, if that happens, the land over it will be radioactive for centuries at the least. The reactions themselves will stop eventually, but so much radiation will have been pumped out by then that it won't matter.

The other factor is the fact that it's going to be years before these stations are safe to use again regardless of outcome.

[perihelion]

[sigh]  I guess I'm either not communicating effectively or am talking about technical details most people don't know about.  Klaustraphobia, would you help me out a little?

I am not talking about radioactivity in general.  I am talking about specific short-lived byproducts that contribute a significant amount to the total heat output of a functioning fission reactor (I've heard 6 - 7% bandied about, but it's been awhile since I read up).  The fuel rods will be nasty and radioactive for uncounted years, yes, but their heat output will only be sufficient to cause them to melt until enough of the short-term fission byproducts have decayed.  When the rate of heat generated by decay drops down to the rate at which heat can be passively removed from the fuel rods (without an active cooling loop in motion) there is no longer a risk of the fuel rods melting.

Those pumps eventually get shut down during turnaround.  It isn't like the fuel rods must have water circulating over them indefinitely.

EDIT: Now reading I may be incorrect in this assumption.  The fuel rods may not cool off enough that they are passively safe from melt down for years.  Apparently spent fuel pools are actively cooled as well.  I did not think this was the case.

[Suongadon]

How long it takes depends on how well they can sustain the coolant flow without incident, and the concentration//efficacy of poison (boric acid still?) in the coolant flow. It could be as little as a week or maybe two of a fully filled reactor vessel and no interruption of flow, or this could go on for months. I suspect that, as the further it goes past the lower number, the closer the Japanese government comes to nuking it from orbit writing the area off and dumping as much boric acid and concrete as they can find on top of it.