Comments on: So we know this stuff is bad, but...
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Comments on Ask MetaFilter post So we know this stuff is bad, but...Tue, 20 Apr 2010 11:06:47 -0800Tue, 20 Apr 2010 11:06:47 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Question: So we know this stuff is bad, but...
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but
How many tons of ash has the volcano in Iceland erupted? <br /><br /> I'm looking for numbers about what exactly Eyjafjallajoekull is shooting out. I've found 150-300,000 tons of CO2/day, but gas isn't nearly as fun as solids. <br>
<br>
<a href="http://www2.norvol.hi.is/page/IES-EY-CEMCOM">This </a>will tell me what's <em>in</em> the ash, and <a href="http://www2.norvol.hi.is/page/ies_Eyjafjallajokull_eruption">this </a>will tell me about the <em>magma</em>, but nothing about how much ash! (Although maybe that's "Tephra fallout from eruption plume"?)post:ask.metafilter.com,2010:site.151723Tue, 20 Apr 2010 10:56:04 -0800jenmessvolcanoeruptionicelandBy: jedicus
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2173666
About <a href="http://www.earthice.hi.is/page/ies_Eyjafjallajokull_eruption?79,61">100 million cubic meters</a> of airborne <a href="http://en.wikipedia.org/wiki/Tephra">tephra</a>, most of which was <a href="http://www.earthice.hi.is/Apps/WebObjects/HI.woa/swdocument/1015805/Report+on+14+April+Eyjafjoll+eruption+%C3%9E%C3%9E+GL+AH.pdf">very fine grained</a> [pdf] and therefore classifiable as ash.comment:ask.metafilter.com,2010:site.151723-2173666Tue, 20 Apr 2010 11:06:47 -0800jedicusBy: jedicus
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2173671
That's for the first 72 hours of the eruption, by the way. Presumably more has been released since.comment:ask.metafilter.com,2010:site.151723-2173671Tue, 20 Apr 2010 11:07:48 -0800jedicusBy: jedicus
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2173697
Oh, to convert to tons we can use some<a href="http://volcanoes.usgs.gov/ash/properties.html#density"> general information about the density of volcanic ash</a>. Since the tephra in question is very fine-grained, we'll use the values for pumice fragments, which are the lightest kind of ash in that table. At 100 million cubic meters and 700-1200 kg/cubic meter, we get something like 17 billion - 120 billion kg. If you want tons (the 2000 lb variety), that's 18.7 million - 132 million short tons.<br>
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For comparison, <a href="http://vulcan.wr.usgs.gov/Volcanoes/MSH/Publications/MSHPPF/MSH_past_present_future.html">the 1980 eruption of Mt. St. Helens released 540 million tons of ash</a>.comment:ask.metafilter.com,2010:site.151723-2173697Tue, 20 Apr 2010 11:16:35 -0800jedicusBy: _dario
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2173853
aside: the total surface (land only) of the EU is about 4.32 millions sqkm; neglecting mountains, and considering an altitude of up to 37,000ft (11km) for the airspace I get an approximate volume of 47.52 millions cubic km. (1 cubic km = 10^9 cubic m) which, divided by the above quoted volume of eject (tephra, ash, etc) gives me an average volume ratio of 1 part ash over 475 millions parts air. <br>
It's obvious that the distribution is very inequal, but I'm starting to suspect that all this was a little overestimated by the EU authorities.comment:ask.metafilter.com,2010:site.151723-2173853Tue, 20 Apr 2010 12:47:40 -0800_darioBy: flif
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2173956
Caveat: I know nothing about jet engines, not good at physics, and very naive assumptions are made below.<br>
<br>
Berlin to Paris is ~1000 km = 10<sup>6</sup> m.<br>
Jet engine intake is ~2 m in diameter, 3.14 m<sup>2</sup>.<br>
So during this travel, the air intake is 3.14*10<sup>6</sup> m<sup>3</sup> per engine.<br>
Using 1 part ash / 475 million parts air gives 0.0066 m<sup>3</sup> ~ 6.6 liters ash.comment:ask.metafilter.com,2010:site.151723-2173956Tue, 20 Apr 2010 14:05:16 -0800flifBy: Chocolate Pickle
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2174207
Eruption ejecta totals are usually expressed in cubic kilometers, simply because units like "kilograms" are so ridiculously small. Mt. St. Helens released about a cubic kilometer of ash.comment:ask.metafilter.com,2010:site.151723-2174207Tue, 20 Apr 2010 17:14:31 -0800Chocolate PickleBy: _dario
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2174398
flif, you make an excellent point.comment:ask.metafilter.com,2010:site.151723-2174398Tue, 20 Apr 2010 20:32:31 -0800_darioBy: defcom1
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2174461
flif, you miss one important argument. Air intake is not equal to area x distance travelled. <br>
Air flow through <a href="http://www.stanford.edu/~cantwell/AA283_Course_Material/GE90_Engine_Data.pdf">GE-90 (Boeing 777 engine) is 1350kg/sec</a>. Density of air at 35000ft is .1841kg/m3. This engine moves 7,300m3/sec of air through it.<br>
1 hour flying..2.6x10^7 m3 of air.comment:ask.metafilter.com,2010:site.151723-2174461Tue, 20 Apr 2010 21:41:30 -0800defcom1By: _dario
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2174545
defcom1: exactly. According to flif's calculation, a theoretical plane, flying across from Paris to Berlin in my theoretical "same density of ash everywhere" sky, with its engines turned off would intercept 6.6 liters ash. Per engine.comment:ask.metafilter.com,2010:site.151723-2174545Wed, 21 Apr 2010 00:58:56 -0800_darioBy: defcom1
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2174653
huh? I must be missing something :( (I'm not disagreeing with your statement, just puzzled...?) <a href="http://en.wikipedia.org/wiki/KLM_Flight_867"> Ash BAAAAD.</a> And off topic. Sorry OP.comment:ask.metafilter.com,2010:site.151723-2174653Wed, 21 Apr 2010 05:56:18 -0800defcom1By: soma lkzx
http://ask.metafilter.com/151723/So-we-know-this-stuff-is-bad-but#2175412
well why don't we up and make an <a href="http://xoxosoma.com/iceland/">infographic</a> about itcomment:ask.metafilter.com,2010:site.151723-2175412Wed, 21 Apr 2010 14:14:31 -0800soma lkzx