<p>Just to add some further discussion to <a href="https://earthscience.stackexchange.com/a/4721/2810">@Pont</a> and <a href="https://earthscience.stackexchange.com/a/4722/2810">@fre0n</a> excellent answers. </p>

<p>The problem of the <a href="http://en.wikipedia.org/wiki/Flood_geology" rel="nofollow noreferrer">water needed</a> to submerge the world during the <a href="https://www.biblegateway.com/passage/?search=Genesis%207" rel="nofollow noreferrer">Genesis flood</a> have been discussed for centuries. The narrative could seem legit as  traces of marine condition can be seen even in high mountains. The Biblical flood was the most logic explanation for marine fossils and wave patterns far away from any coast. Moreover, at the time when the Bible was written in the Levant, there might still have been a collective memory of sudden sea level rise from the possible opening of Bosporus and <a href="http://en.wikipedia.org/wiki/Black_Sea_deluge_hypothesis" rel="nofollow noreferrer">flooding of the Black Sea</a>. Other experiences, as <a href="http://www.bbc.co.uk/history/ancient/greeks/minoan_01.shtml" rel="nofollow noreferrer">tsunamis</a> formed in the tectonic active Eastern Mediterranean would also add to the idea of flooding as a divine respond to human actions. </p>

<p>Early scientists that described and compared features in the nature, e.g. <a href="http://muslimheritage.com/article/contribution-ibn-sina-development-earth-sciences" rel="nofollow noreferrer">Ibn-Sinaa</a>, could also see that some rocks was formed by water. They added the superposition principle, that younger rocks are situated above older rocks and that the processes that formed the rocks <a href="http://en.wikipedia.org/wiki/Uniformitarianism" rel="nofollow noreferrer">continues today</a> and must have taken long time. What they could see, describe and test was a continuation of the earlier ideas of flooding, but they used reason instead of dogma. Modern disciplines of science, as <a href="http://en.wikipedia.org/wiki/Radiometric_dating" rel="nofollow noreferrer">radiometric dating</a> and <a href="http://en.wikipedia.org/wiki/Evolutionary_taxonomy" rel="nofollow noreferrer">taxonomy</a>, have further refined our understanding of time and the relation between water and dry ground, but we are still building on the traditions of earlier scholars as Ibn-Sinaa. Sometimes we prove them wrong, just like future scientists will (hopefully) prove us wrong, but the human wish to understand the nature around us can easily be traced back to Old Testament and before. </p>

<p>Sea levels are constantly changing during the history of Earth. There is a number of parameters that controls the global sea level, some are <a href="http://en.wikipedia.org/wiki/Sea_level#Geological_influences" rel="nofollow noreferrer">slow</a> but have a large impact. E.g. during Ordovician, the sea level might have been 3-400m higher than today. Not enough to reach the foot of modern Mt Ararat, but the planet was certainly more blue when the first fishes appeared. Also during Cretaceous, the sea level was 2-300m higher than today and more recent, in early Holocene, the sea level was 120m lower than today. Our ancestors could walk (and maybe a short swim or paddle) from Asia to Alaska, from Java to Australia, and across the Black Sea.</p>

<p><img src="https://i.sstatic.net/VR9VM.png" alt="Picture from the net. I hope it&#39;s correct and allowed to use."></p>

<p>So where did the water go? At colder conditions water can be be trapped in ice shields, glaciers. Antarctica and Greenland holds a rather large fraction of the global fresh water. But most water are in the oceans, and larger sea level changes must be caused by changes of the oceans. </p>

<p><img src="https://i.sstatic.net/q7DdG.png" alt="USGS – Earth&#39;s water distribution By Cmglee (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons"></p>

<p>The oceanic crust is, relatively to the continental crust, thin and soft, but get harder and chemically heavier with age. The oceanic crust press down the <a href="http://en.wikipedia.org/wiki/Asthenosphere" rel="nofollow noreferrer">asthenosphere</a> and this results in more space for water, and the sea level sinks (in relation to the <a href="http://en.wikipedia.org/wiki/Geoid" rel="nofollow noreferrer">geoid</a>). Mid-ocean volcanism on the other hand lifts the seafloor and forces the sea level to rise. Temperature of water is also a factor to consider. Warm water is has less density and occupies larger volume. </p>

<p><img src="https://i.sstatic.net/zrsmz.png" alt="Phanerozoic Sea Level&quot;. Licensed under CC BY-SA 3.0 via Wikimedia Commons"></p>

<p>The total change in sea level in the past 500 million years have been estimated to about 500m, this is impressive, but far more than the 3,896m of Mt Ararat, that was supposed to be covered in the Genesis <a href="http://en.wikipedia.org/wiki/Flood_myth" rel="nofollow noreferrer">flood narrative</a>. As mentioned, there might be more <a href="http://www.sciencemag.org/content/344/6189/1265.abstract?sid=d573efc5-c389-4b1a-a4be-19fa8a3301de" rel="nofollow noreferrer">water</a> trapped in the <a href="http://en.wikipedia.org/wiki/Transition_zone_%28Earth%29" rel="nofollow noreferrer">mantle transition zone</a>, but it's hard to see how it could have slipped out to form liquid water, and even more difficult, how it could get back to the mantle, against gravity, after the flood. </p>

<p>However, as a homage to the Biblical believes, there could be an interesting link between sea level changes and mass extinction. Changing sea levels, especially when it happens rapidly, results in new conditions that species might not have time to <a href="http://en.wikipedia.org/wiki/Adaptation" rel="nofollow noreferrer">adapt</a> to. The connection is discussed in <a href="http://www.sciencedirect.com/science/article/pii/S0012825299000550" rel="nofollow noreferrer">this</a> article by Hallam and Wignall, 1999 (<a href="http://studentresearch.wcp.muohio.edu/extinctionsradiations/massextinctionsealevel.pdf" rel="nofollow noreferrer">Mass extinctions and sea-level changes</a>). The article is also a good example of scientific methods and reason. The language in a scientific article might not be so colorful as in Genesis, but it can open a world far more complex and wonderful than any dogma.</p>

<p>Finally, a reading tip: 
One solution is proposed in Umberto Eco's <a href="http://www.goodreads.com/book/show/10506.The_Island_of_the_Day_Before" rel="nofollow noreferrer">The Island of the Day Before</a>, maybe the water was borrowed from another day, as the Earth contains two days, separated by the <a href="http://en.wikipedia.org/wiki/International_Date_Line" rel="nofollow noreferrer">date line</a>. </p>

CC BY-SA 3.0
2017-01-29T17:23:05.387Z
Note that most of the Earth's water is not "in the Ocean", most water is in the Earth's interior. The cube diagram above is missing that. Check ref cited here: https://www.theguardian.com/science/2014/jun/13/earth-may-have-underground-ocean-three-times-that-on-surface , Of course, nobody knows of a mechanism to bring that water catastrophically to the surface
DrGC
CC BY-SA 3.0
2017-01-29T17:32:05.007Z
It is mentioned in the answer, if you read further. The water in the mantel is well known, but it's very difficult to estimate. At the moment a lot of interesting research is done to quantify the amount of water in the mantle.
user2821
CC BY-SA 3.0
2015-04-21T23:55:09.550Z
Very good answer. I enjoyed learning from it.
arkaia
CC BY-SA 3.0
2015-04-22T01:15:59.707Z
@Tobbe  Excellent answer - Further, the cube figure you presented is quite a way to efficiently describe the overall earth water compartmentalization; I am curious if there exist a reference for this I would consider using this style of representation in a slide for courses or presentation (if it is permitted license-wise)
marsisalie
CC BY-SA 3.0
2015-04-22T05:23:56.277Z
@fre0n A reverse Google image search found [the source for the image](http://en.wikipedia.org/wiki/Water_distribution_on_Earth#/media/File:Earth_water_distribution.svg). It's under the [Creative Commons BY-SA 3.0](http://creativecommons.org/licenses/by-sa/3.0/) licence so use in a presentation should be fine.
Pont
CC BY-SA 3.0
2015-05-17T16:31:04.203Z
See also this answer for a more detailed discussion on changed sea levels: http://earthscience.stackexchange.com/a/2557/2536
user2821
CC BY-SA 3.0
2015-04-21T23:51:15.817Z
2015-09-12T08:39:24.303Z
2017-04-13T12:50:30.540Z
user2821
<p>The "precipitation rate" part is easy to answer, at least to a first approximation. We have 40 days and nights (960 hours) in which to raise sea level above the peak of Mount Everest (let's round up and call it 9000m). Thus, we need a precipitation rate of around 9000/960 =~ 9.4 <em>metres</em> per hour. For comparison, the largest rainfall ever recorded over an hour is <a href="http://en.wikipedia.org/wiki/List_of_weather_records#Rain">305mm</a>. So a Noachian flood would require a precipitation rate over 30 times greater than the highest-ever recorded one-hour rate at a single site, sustained continuously over every point on the globe for the entire 40 days and nights.</p>

CC BY-SA 3.0
2015-04-22T14:11:43.393Z
From Genesis 8:2, it seems there were 2 other sources of water in addition to rain: "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "  So there was water coming form "the deep" and well as from above.  http://www.mechon-mamre.org/p/pt/pt0108.htm
DavePhD
CC BY-SA 3.0
2015-04-22T14:57:26.470Z
@DavePhD Good point -- I suspect the "windows of heaven" might just be the supposed origin of the rain, but the "springs of the deep" (which are also mentioned in Genesis 7:11) can't be explained away so easily. But the question seems to be asking specifically for an equivalent precipitation rate, so I think this should be a sufficient answer. At the very least it could give us a baseline figure from which to estimate the required discharge rate from the "springs of the deep", whatever they may be (hydrothermal vents, perhaps?).
Pont
CC BY-SA 3.0
2015-04-21T15:20:31.527Z
2015-04-21T15:20:31.527Z
Pont
<blockquote>
  <p>1.Given the amount of water on Earth (including all the water as liquid, solid, and gas, in all possible places: the atmosphere, the surface, and underground), is there enough water to flood the whole earth until ‘all the high mountains… were covered’?</p>
</blockquote>

<p>Yes.  According to <a href="http://www.newscientist.com/article/dn25723-massive-ocean-discovered-towards-earths-core.html" rel="noreferrer">Massive 'ocean' discovered towards Earth's core</a></p>

<blockquote>
  <p>A reservoir of water three times the volume of all the oceans has been discovered deep beneath the Earth's surface. </p>
</blockquote>

<p>Considering that the average depth of the ocean is 2.3 miles and the Earth is 71% water, three times this amount would be about the amount needed to reach the top of the highest mountains.  </p>

<blockquote>
  <p>2.What is the estimated rainfall intensity based on this description, and how intense is it in comparison with today’s rainfall intensity in tropical areas?</p>
</blockquote>

<p>There is no way to estimate rain fall from the description, because Genesis makes clear water came from "the deep" as well as from above.  For example the passage qouted in the OP says "springs of the great deep burst forth" and Genesis 8:2 says "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "</p>

CC BY-SA 3.0
2015-04-22T19:13:47.773Z
It's an interesting point, but the water in the transition zone is not water as we think about it in aquifers, something that is in contact with surface water and the oceans. It is rather a content of hydrogen and oxygen probably originating in subducted ocean crust. Schmandt et al 2014 talks about an extended water cycle, and the time frame is in the magnitude of Wilson cycles. We would need a good model for why all the 'water' in the mantle suddenly leaves the mantle and penetrate the crust. Even more difficult is to explain how the water suddenly would reenter the mantle, against gravity.
user2821
CC BY-SA 3.0
2015-04-22T14:46:11.670Z
2015-04-22T14:46:11.670Z
DavePhD
<p>Without requiring any rainfall, if you accept a theoretical scenario of a "dead Earth", meaning with no more active tectonics, no flux of heat from the mantle/core and given a long-enough time to almost completely erode mountains, then yes, a complete global flood may be possible. Just imagine to displace all the rocks that today are above the average sea level into the oceanic basins, then let them to compact (reducing porosity) and to reach isostatic equilibrium, pushing water above the sediments by density difference. </p>

<p>The thought experiment may then continue, calculating the average altitude of sediments and the average height of the water column above the surface in that case. A rough estimation should be in the order of a couple thousands meters of water above the global seafloor.</p>

<p>However I do not suppose that this may happen in 40 days, or anytime soon.</p>

CC BY-SA 3.0
2015-04-22T20:15:29.703Z
2015-04-22T20:15:29.703Z
furins
<p>If you'll accept a much slower rain it could happen.  Consider:  As others have shown there is not enough water <strong>on Earth</strong> to do this.  Since there's no feasible mechanism to get all the water on Earth into rain in the first place this isn't all that important anyway.</p>

<p>Instead, lets look elsewhere for the source of our rain:  A large comet.  It's captured by the Earth with the assistance of the Moon but it's in an orbit with a very low perigee.  Comet stuff is shed, hits the atmosphere and comes down.  Since it's mostly gas and ice you get rain, rain and more rain.</p>

<p>This can't happen in 40 days, though--there has to be enough time for it to cool.  If that much water comes down in 40 days it's going to make Venus look positively arctic by comparison.</p>

<p>Thus it's possible for the Earth to become a waterworld like in the movie but not like in <em>Genesis</em>.</p>

CC BY-SA 3.0
2016-07-02T21:25:30.990Z
@Mark, old question I realize, but you wouldn't need to flood the entire world by raising sea level that much.  You'd only need a storm surge maybe 10 miles high.  Displaced water causes floods.     There's enough water on Earth to flood the Earth, if you don't mind the flood being temporary.  (Most floods are temporary).   It would still take a gargantuan amount of energy though, a level 15 earthquake perhaps (which is probably impossible), or a meteor twice the size of the one that killed the dinosaurs (that would cause other serious problems in addition to a global tidal-wave).
userLTK
CC BY-SA 3.0
2016-07-02T21:29:09.883Z
A mantle plume under an ocean mgiht do it, theoretically.   Enough magma create a significant and permanent to boil in an ocean could fill the air with enough water vapor and make it rain for longer than 40 days and 40 nights, Melt the ice caps over time and not literally or completely, but in a practical sense, flood much of the Earth.
userLTK
CC BY-SA 3.0
2016-07-05T20:17:07.527Z
@userLTK That provides the 40 days and nights of rain, it doesn't flood the Earth in the process.
Loren Pechtel
CC BY-SA 3.0
2016-07-06T00:19:09.903Z
@LorenPechtel true, but in combination with a really massive tsunami, much of the Earth could be flooded.   If the Chicxulub impactor had hit square in the pacific ocean, the tidal surge could have swept over the entire United States and Asia.   My point is that floods are usually temporary, not permanent changes in sea level, though they can be some of both.   The initial eruption of a mantle plume and super volcano might create a really big flood, and, followed by 40 days of rain.   It's still an improbable scenario.  I'm just thinking of ways it might happen without adding water.
userLTK
CC BY-SA 3.0
2015-04-22T23:06:44.397Z
The typical comet might have a thousand cubic kilometers of water.  Submerging Mount Everest requires about 4 400 000 000 cubic kilometers.  Bit of a difference there.
Mark
CC BY-SA 3.0
2015-04-22T23:13:29.830Z
@Mark Yeah, I said "large"--I realize the average one won't do it.  There are suitable bodies in the Oort cloud, though.
Loren Pechtel
CC BY-SA 3.0
2015-04-22T23:17:23.933Z
I believe Comet Hale-Bopp is the largest known comet.  If we take the upper bound for size estimate (40 km radius) and assume it's a sphere of pure water, that's still only about 200 000 cubic kilometers -- you'd need 22000 of them to flood the Earth.
Mark
CC BY-SA 3.0
2015-04-22T23:27:20.850Z
As for Oort cloud bodies, if you assume it's pure water, you're looking for something at least 1100 km in radius -- something on a par with Pluto or Eris, and visually not much smaller than Earth's Moon.  We normally call these "dwarf planets", not "comets".
Mark
CC BY-SA 3.0
2015-04-22T23:40:36.520Z
@Mark I think your size is a bit off but I'll accept calling it a dwarf planet.  The basic idea is an extraterrestrial source, the size of the needed body is quibbling about details.
Loren Pechtel
CC BY-SA 3.0
2015-04-23T03:37:53.723Z
The problem with a comet, or comet-like larger body, is that it's going to come down with a heck of a bang.  Maybe not quite enough to splash off a second moon (see http://en.wikipedia.org/wiki/Giant_impact_hypothesis ), but I would think at least enough to melt the crust.
jamesqf
CC BY-SA 3.0
2015-04-23T17:29:39.443Z
@jamesqf A hit from a body that could deliver that much water would be an extinction event.  Note, however, that I am **not** figuring a hit, but rather orbital capture followed by a slow entry of the debris torn off by passing within the Roche limit.
Loren Pechtel
CC BY-SA 3.0
2015-04-23T18:53:28.120Z
@Loren Pechtel:  It can't be that slow, though, since (according to the claim) the Flood happened in 40 days.  So at a minimum, you've got extreme atmospheric heating from the entry of that much mass - which can't enter at less than orbital velocity, at least in any way I can think of.  (And of course we're still left with the question of what happened to all that water afterwards...)
jamesqf
CC BY-SA 3.0
2015-04-23T19:46:07.160Z
@jamesqf Note my first sentence.  I'm saying a global flood (*Waterworld*) is possible but the *Genesis* version of such a flood is not.
Loren Pechtel
CC BY-SA 3.0
2015-04-22T02:03:24.797Z
2015-04-22T02:03:24.797Z
Loren Pechtel
<p>The primary source for the water that generated the flood was neither the upper mantle nor the atmosphere as rainfall, nor cometary bombardment or grazing, but earth's existing ocean water itself. Some water is liberated from the mantle in volcanoes and undersea vents, but these amounts are negligible except over very long periods of time.
Planet earth has a large amount of radioactive elements in its core and lower mantle. Radioactive element decay sequences, if they occur synchronized, could generate significant and rapid changes in the volume occupied by the elements, therefore, could rapidly change Earth's volume, same as a star can change volume in a collapse towards its core or in red giant phase but by a different process. If earth were to have shrunk, it would have displaced earths oceans to overwhelm the continents in wave after wave of tsunamis. If as the decay sequence continues, earths volume again increased, the water would have been displaced off the continents back into the ocean basins. No extra mystery water is needed to generate the flood, and no mystery as to where all the extra water went after the flood.
This radioactive decay would have generated massive heat, which would have shut off earth's protective electromagnetic field generating dynamo; however, an expanding earth would also create large rifts, and expose earth's mantle to the oceans, generating mass extinctions in the oceans, massive rainfall in equatorial regions, and massive blizzards at the poles; ergo, the ice ages; extreme cloud cover would have protected earth's life from cosmic rays till the dynamo turned back on; when the EMF turned back on centuries later, with rapid fluctuations, it seems to have generated a memory scrambling effect, recorded as The Tower of Babel event as the scrambling of languages.</p>

CC BY-SA 3.0
2015-09-12T09:47:54.777Z
Nice that you mention *The Tower of Babel event as the scrambling of languages* at the end, because that is exactly what this [wall of text](http://uncyclopedia.wikia.com/wiki/Wall_of_Text) looks like. [Edit] your answer so that it is readable.
Jan Doggen
CC BY-SA 3.0
2015-09-12T00:55:39.170Z
2015-09-12T00:55:39.170Z
ONE WHITE CROW
<p>there is not enough existing water inside this geosystem IMO for such a thing to occur. Let's see these figures here:</p>

<p><a href="https://water.usgs.gov/edu/earthhowmuch.html" rel="nofollow noreferrer">One estimate of global water distribution</a></p>

<p>Oceans, Seas, &amp; Bays 1,338,000,000  --  96.54% of all water</p>

<p>this figure means that most of the existing water at the global scale is seawater. Sea floor is quite irregular, with some abyss like pits (ex: Mariana trench), up to low water in shallow sea near continents and islands (See figure). A variable topography overall</p>

<p><img src="https://i.sstatic.net/cw8RF.png" alt="Sea depth - division"></p>

<p>This mean that considering the current volume of existing sea water, at say an average of 3 km depth (hypothetical, but it doesn't change the overall reasoning), and removing the continents,  you would have to double, and probably more than double the current volume of sea water to raise the oceanic water level of 1 km, 2 km etc... or ~5 km if we consider MT Ararat.</p>

<p>Here is some hypothetically (rough) calculation to illustrate. Let's say the Earth have a surface area of 510 million km<sup>2</sup> (<a href="http://en.wikipedia.org/wiki/Earth" rel="nofollow noreferrer">Wikipedia</a>) and the overall global water (USGS link in my post) amount to 1386 million km<sup>2</sup>. Dividing the volume by the surface provides the height, as shown by this dimensional analysis :$\frac {L^3}{L^2}=L$, which would amount to 2.71 km in height in this case. But let's not forget that this figure imply</p>

<p><strong>a)</strong> the impermeability of the surface</p>

<p><strong>b)</strong> the surface flatness.</p>

<p>Multiple problems further arise when considering how such an amount of hypothetical water could be suspended at once - there is a interesting debunking explaining implications here:</p>

<p><a href="http://www.talkorigins.org/faqs/faq-noahs-ark.html#flood" rel="nofollow noreferrer">Talk Origins - 5. the Flood itself</a></p>

<p>I think <a href="https://earthscience.stackexchange.com/a/4721/2810">@Pont</a> nicely answered the subquestion about the precipitation rate</p>

CC BY-SA 3.0
2015-04-22T12:05:29.727Z
If we were to assume the earth was completely flat (no mountains) (**not** flat as in not round). how high/thick would the layer of all water on earth be? (assuming it is all equally distributed and there are no tidal forces) would it be 1km?
Vincent
CC BY-SA 3.0
2015-04-22T13:25:39.947Z
@Vincent Advocaat I added some relevant info in the answer as a follow-up to your question
marsisalie
CC BY-SA 3.0
2015-04-21T16:29:44.250Z
2015-09-15T18:41:28.160Z
2017-04-13T12:50:30.540Z
marsisalie
<p><a href="https://www.biblegateway.com/passage/?search=Genesis%207" rel="nofollow noreferrer">Genesis 7:11-20</a> presents an account of an event which, in 40 days, submerges the entire surface of the earth:</p>
<blockquote>
<p>[On] the seventeenth day of the second month — on that day
all the springs of the great deep burst forth, and the
floodgates of the heavens were opened…</p>
<p>For forty days the flood kept coming on the earth… all the high
mountains under the entire heavens were covered. The waters rose
and covered the mountains to a depth of more than fifteen cubits
[6.86 m].</p>
</blockquote>
<p>Based on this account, my questions are:</p>
<ol>
<li><p>Given the amount of water on Earth (including all the water as liquid, solid, and gas, in all possible places: the atmosphere, the surface, and underground), is there enough water to flood the whole earth until ‘all the high mountains… were covered’?</p>
</li>
<li><p>What is the estimated rainfall intensity based on this description, and how intense is it in comparison with today’s rainfall intensity in tropical areas?</p>
</li>
</ol>
<p>Regardless of the veracity or otherwise of the account, this makes for an interesting thought experiment.</p>

CC BY-SA 3.0
2016-07-04T16:08:56.490Z
Is it 'physically' possible? Yes. But you'd essentially have to smooth out all of earth's crust so there aren't any more extremely low or high points. This would not be a familiar earth.
Logan
CC BY-SA 3.0
2015-09-25T23:56:29.663Z
Lengthy books could be written about the geological, hydrological and other absurdities of a literal Noah's flood. All such discussion is a red herring because the Biblical narrative of Genesis 1 to 11 is an allegory. To treat it as a topic of serious scientific discussion is utterly absurd.
Gordon Stanger
CC BY-SA 4.0
2019-04-25T00:20:03.337Z
While it might not be possible with the current land mass of the Earth, there's a lot of evidence to suggest that all or much of the Earth was indeed once covered by water. Scientists tend to agree that the Western United States was once fully covered by ocean. Dinosaurs are scarcely found in that region because the region was oceanic at that time and land mammals were unable to walk in the area. It's possible that these portions of the Earth were covered by water either because land elevation levels have increased since then, or that there was actually more water on Earth at that time.
Michael d
CC BY-SA 4.0
2019-04-25T05:30:50.287Z
@Michaeld is this your opinion or scientific consensus? If it's the latter, can you make it into an answer? Of course you will have to gain some reputation first, the easiest way is to contribute positive edits...
Graviton
CC BY-SA 4.0
2019-04-30T13:10:17.457Z
@Graviton - Just Google "was Nevada covered by water", or simply read the first paragraph of this Wikipedia entry: https://en.wikipedia.org/wiki/Paleontology_in_Nevada - There seems to be plenty of scientists that agree that water covered much of the west coast during prehistoric times. I can't make it into an answer because as you say, apparently I don't have enough rep here to do so. Maybe I'll earn rep eventually but I'm on other stack exchanges as well. If you like my answer, make it into your own answer if you like.
Michael d
CC BY-SA 3.0
2015-04-21T15:07:41.213Z
I have rephrased the question in more neutral terms. Personally I think it makes for an entertaining thought experiment (cf. the recent question about a 1km hole appearing through the Earth).
Pont
CC BY-SA 3.0
2015-04-21T17:25:51.647Z
@Graviton This article by Hallam and Wignall 1999 could be interesting and hopefully inspiring for you. Sea levels have indeed varied a lot i the geological history and some of the variations might be associated to mass extinctions. http://www.sciencedirect.com/science/article/pii/S0012825299000550 full text here: http://studentresearch.wcp.muohio.edu/extinctionsradiations/massextinctionsealevel.pdf
user2821
CC BY-SA 3.0
2015-04-22T11:29:47.543Z
Don't forget depths of ocean floors and heights of mountains could have been different in the remote past when the flood story is set. We know plate tectonics is constantly altering the shapes of continents. If a deal of water was locked up in minerals or ice and then melted it would take a while to settle into oceans and the weight of so much water could have resulted in the ocean floor sinking to the extent we now find it. After all a cubic kilometre of water weighs a billion tons.
jrrk
CC BY-SA 3.0
2015-04-22T14:25:56.170Z
The "known" Earth was much smaller when this was written.  You might have a more realistic account if you just considered Eurasia/Africa to be flooding.  That being said...7 meters sea level rise is roughly what we would expect if all ice (other than Antarctica) was converted to water.
f.thorpe
CC BY-SA 3.0
2015-04-22T14:30:38.120Z
Genesis is not describing solely a "precipitation even".  The quoted passage says "spings of the great deep" and Genesis 8:2 says: "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "  Precipitation was only one of the components of the event.
DavePhD
CC BY-SA 3.0
2015-04-22T20:53:41.600Z
Flood: Stephen Baxter: 9780451463289, explores the idea of a global flood.
Phil
CC BY-SA 3.0
2015-04-23T03:29:47.250Z
@farrenthorpe: But the original source doesn't say "known Earth", "local area", or anything like that.  It says the whole Earth.  And since the purported author is claimed to be omniscient, we have to take that at face value :-)
jamesqf
CC BY-SA 3.0
2015-04-23T14:58:50.077Z
@jamesqf the purpoted authors are of Greek origin... not omniscient.  We can estimate the century it was written and the knowledge of Earth that the Greeks had at that time.
f.thorpe
CC BY-SA 3.0
2015-04-23T18:46:53.430Z
@farrenthorpe: Huh?  Genesis written by authors of Greek origin?  It was first written in ancient Hebrew, surely?  And the people who wrote it down were merely stenographers of sorts, transcribing the Word of the Author, no?  Also, we know that (according to internal evidence in the document) this Flood happened in 2348 BCE, long before classical Greece.
jamesqf
CC BY-SA 3.0
2015-04-24T04:25:08.737Z
@jamesqf thank you for the correction!  I still say the known world at the time is what the human author was writing about.
f.thorpe
CC BY-SA 3.0
2015-04-26T12:49:50.330Z
@ACuriousJim If you read the full account in Genesis, you will notice that the water didn't just come from the clouds. Also, perhaps the atmosphere was enough different then that there would have been enough moisture in the atmosphere to produce such a flood.
L.B.
<meteorology><hypothetical><water><geomythology><flooding>
Is a complete global flood physically possible on Earth?
Graviton
# Is a complete global flood physically possible on Earth?

(Asked by: username_0 on 2015-04-21)

[Genesis 7:11-20](https://www.biblegateway.com/passage/?search=Genesis%207) presents an account of an event which, in 40 days, submerges the entire surface of the earth:

> [On] the seventeenth day of the second month — on that day
> all the springs of the great deep burst forth, and the
> floodgates of the heavens were opened…
>
> For forty days the flood kept coming on the earth… all the high
> mountains under the entire heavens were covered. The waters rose
> and covered the mountains to a depth of more than fifteen cubits
> [6.86 m].

Based on this account, my questions are:

1. Given the amount of water on Earth (including all the water as liquid, solid, and gas, in all possible places: the atmosphere, the surface, and underground), is there enough water to flood the whole earth until ‘all the high mountains… were covered’?
2. What is the estimated rainfall intensity based on this description, and how intense is it in comparison with today’s rainfall intensity in tropical areas?

Regardless of the veracity or otherwise of the account, this makes for an interesting thought experiment.

**Tags:** meteorology, hypothetical, water, geomythology, flooding

> **Comments:**
> **username_4**: I have rephrased the question in more neutral terms. Personally I think it makes for an entertaining thought experiment (cf. the recent question about a 1km hole appearing through the Earth).  
> **username_5**: @username_0 This article by Hallam and Wignall 1999 could be interesting and hopefully inspiring for you. Sea levels have indeed varied a lot i the geological history and some of the variations might be associated to mass extinctions. http://www.sciencedirect.com/science/article/pii/S0012825299000550 full text here: http://studentresearch.wcp.muohio.edu/extinctionsradiations/massextinctionsealevel.pdf  
> **username_6**: Don't forget depths of ocean floors and heights of mountains could have been different in the remote past when the flood story is set. We know plate tectonics is constantly altering the shapes of continents. If a deal of water was locked up in minerals or ice and then melted it would take a while to settle into oceans and the weight of so much water could have resulted in the ocean floor sinking to the extent we now find it. After all a cubic kilometre of water weighs a billion tons.  
> **username_7**: The "known" Earth was much smaller when this was written.  You might have a more realistic account if you just considered Eurasia/Africa to be flooding.  That being said...7 meters sea level rise is roughly what we would expect if all ice (other than Antarctica) was converted to water.  
> **username_8**: Genesis is not describing solely a "precipitation even".  The quoted passage says "spings of the great deep" and Genesis 8:2 says: "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "  Precipitation was only one of the components of the event.  
> **username_9**: Flood: Stephen Baxter: 9780451463289, explores the idea of a global flood.  
> **username_10**: @farrenthorpe: But the original source doesn't say "known Earth", "local area", or anything like that.  It says the whole Earth.  And since the purported author is claimed to be omniscient, we have to take that at face value :-)  
> **username_7**: @username_10 the purpoted authors are of Greek origin... not omniscient.  We can estimate the century it was written and the knowledge of Earth that the Greeks had at that time.  
> **username_10**: @farrenthorpe: Huh?  Genesis written by authors of Greek origin?  It was first written in ancient Hebrew, surely?  And the people who wrote it down were merely stenographers of sorts, transcribing the Word of the Author, no?  Also, we know that (according to internal evidence in the document) this Flood happened in 2348 BCE, long before classical Greece.  
> **username_7**: @username_10 thank you for the correction!  I still say the known world at the time is what the human author was writing about.  
> **username_11**: @ACuriousJim If you read the full account in Genesis, you will notice that the water didn't just come from the clouds. Also, perhaps the atmosphere was enough different then that there would have been enough moisture in the atmosphere to produce such a flood.  
> **username_2**: Lengthy books could be written about the geological, hydrological and other absurdities of a literal Noah's flood. All such discussion is a red herring because the Biblical narrative of Genesis 1 to 11 is an allegory. To treat it as a topic of serious scientific discussion is utterly absurd.  
> **username_1**: Is it 'physically' possible? Yes. But you'd essentially have to smooth out all of earth's crust so there aren't any more extremely low or high points. This would not be a familiar earth.  
> **username_3**: While it might not be possible with the current land mass of the Earth, there's a lot of evidence to suggest that all or much of the Earth was indeed once covered by water. Scientists tend to agree that the Western United States was once fully covered by ocean. Dinosaurs are scarcely found in that region because the region was oceanic at that time and land mammals were unable to walk in the area. It's possible that these portions of the Earth were covered by water either because land elevation levels have increased since then, or that there was actually more water on Earth at that time.  
> **username_0**: @username_3 is this your opinion or scientific consensus? If it's the latter, can you make it into an answer? Of course you will have to gain some reputation first, the easiest way is to contribute positive edits...  
> **username_3**: @username_0 - Just Google "was Nevada covered by water", or simply read the first paragraph of this Wikipedia entry: https://en.wikipedia.org/wiki/Paleontology_in_Nevada - There seems to be plenty of scientists that agree that water covered much of the west coast during prehistoric times. I can't make it into an answer because as you say, apparently I don't have enough rep here to do so. Maybe I'll earn rep eventually but I'm on other stack exchanges as well. If you like my answer, make it into your own answer if you like.  

---

## 7 answers

### Answer by username_14 on 2015-04-21. Score: 23 | Accepted answer

there is not enough existing water inside this geosystem IMO for such a thing to occur. Let's see these figures here:

[One estimate of global water distribution](https://water.usgs.gov/edu/earthhowmuch.html)

Oceans, Seas, & Bays 1,338,000,000 -- 96.54% of all water

this figure means that most of the existing water at the global scale is seawater. Sea floor is quite irregular, with some abyss like pits (ex: Mariana trench), up to low water in shallow sea near continents and islands (See figure). A variable topography overall

![Sea depth - division](https://i.sstatic.net/cw8RF.png)

This mean that considering the current volume of existing sea water, at say an average of 3 km depth (hypothetical, but it doesn't change the overall reasoning), and removing the continents, you would have to double, and probably more than double the current volume of sea water to raise the oceanic water level of 1 km, 2 km etc... or ~5 km if we consider MT Ararat.

Here is some hypothetically (rough) calculation to illustrate. Let's say the Earth have a surface area of 510 million km2 ([Wikipedia](http://en.wikipedia.org/wiki/Earth)) and the overall global water (USGS link in my post) amount to 1386 million km2. Dividing the volume by the surface provides the height, as shown by this dimensional analysis :$\frac {L^3}{L^2}=L$, which would amount to 2.71 km in height in this case. But let's not forget that this figure imply

**a)** the impermeability of the surface

**b)** the surface flatness.

Multiple problems further arise when considering how such an amount of hypothetical water could be suspended at once - there is a interesting debunking explaining implications here:

[Talk Origins - 5. the Flood itself](http://www.talkorigins.org/faqs/faq-noahs-ark.html#flood)

I think [@username_4](https://earthscience.stackexchange.com/a/4721/2810) nicely answered the subquestion about the precipitation rate

> **Comments:**
> **username_21**: If we were to assume the earth was completely flat (no mountains) (**not** flat as in not round). how high/thick would the layer of all water on earth be? (assuming it is all equally distributed and there are no tidal forces) would it be 1km?  
> **username_14**: @username_21 Advocaat I added some relevant info in the answer as a follow-up to your question  

---

### Answer by username_5 on 2015-04-21. Score: 30

Just to add some further discussion to [@username_4](https://earthscience.stackexchange.com/a/4721/2810) and [@fre0n](https://earthscience.stackexchange.com/a/4722/2810) excellent answers.

The problem of the [water needed](http://en.wikipedia.org/wiki/Flood_geology) to submerge the world during the [Genesis flood](https://www.biblegateway.com/passage/?search=Genesis%207) have been discussed for centuries. The narrative could seem legit as traces of marine condition can be seen even in high mountains. The Biblical flood was the most logic explanation for marine fossils and wave patterns far away from any coast. Moreover, at the time when the Bible was written in the Levant, there might still have been a collective memory of sudden sea level rise from the possible opening of Bosporus and [flooding of the Black Sea](http://en.wikipedia.org/wiki/Black_Sea_deluge_hypothesis). Other experiences, as [tsunamis](http://www.bbc.co.uk/history/ancient/greeks/minoan_01.shtml) formed in the tectonic active Eastern Mediterranean would also add to the idea of flooding as a divine respond to human actions.

Early scientists that described and compared features in the nature, e.g. [Ibn-Sinaa](http://muslimheritage.com/article/contribution-ibn-sina-development-earth-sciences), could also see that some rocks was formed by water. They added the superposition principle, that younger rocks are situated above older rocks and that the processes that formed the rocks [continues today](http://en.wikipedia.org/wiki/Uniformitarianism) and must have taken long time. What they could see, describe and test was a continuation of the earlier ideas of flooding, but they used reason instead of dogma. Modern disciplines of science, as [radiometric dating](http://en.wikipedia.org/wiki/Radiometric_dating) and [taxonomy](http://en.wikipedia.org/wiki/Evolutionary_taxonomy), have further refined our understanding of time and the relation between water and dry ground, but we are still building on the traditions of earlier scholars as Ibn-Sinaa. Sometimes we prove them wrong, just like future scientists will (hopefully) prove us wrong, but the human wish to understand the nature around us can easily be traced back to Old Testament and before.

Sea levels are constantly changing during the history of Earth. There is a number of parameters that controls the global sea level, some are [slow](http://en.wikipedia.org/wiki/Sea_level#Geological_influences) but have a large impact. E.g. during Ordovician, the sea level might have been 3-400m higher than today. Not enough to reach the foot of modern Mt Ararat, but the planet was certainly more blue when the first fishes appeared. Also during Cretaceous, the sea level was 2-300m higher than today and more recent, in early Holocene, the sea level was 120m lower than today. Our ancestors could walk (and maybe a short swim or paddle) from Asia to Alaska, from Java to Australia, and across the Black Sea.

![Picture from the net. I hope it's correct and allowed to use.](https://i.sstatic.net/VR9VM.png)

So where did the water go? At colder conditions water can be be trapped in ice shields, glaciers. Antarctica and Greenland holds a rather large fraction of the global fresh water. But most water are in the oceans, and larger sea level changes must be caused by changes of the oceans.

![USGS – Earth's water distribution By Cmglee (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons](https://i.sstatic.net/q7DdG.png)

The oceanic crust is, relatively to the continental crust, thin and soft, but get harder and chemically heavier with age. The oceanic crust press down the [asthenosphere](http://en.wikipedia.org/wiki/Asthenosphere) and this results in more space for water, and the sea level sinks (in relation to the [geoid](http://en.wikipedia.org/wiki/Geoid)). Mid-ocean volcanism on the other hand lifts the seafloor and forces the sea level to rise. Temperature of water is also a factor to consider. Warm water is has less density and occupies larger volume.

![Phanerozoic Sea Level". Licensed under CC BY-SA 3.0 via Wikimedia Commons](https://i.sstatic.net/zrsmz.png)

The total change in sea level in the past 500 million years have been estimated to about 500m, this is impressive, but far more than the 3,896m of Mt Ararat, that was supposed to be covered in the Genesis [flood narrative](http://en.wikipedia.org/wiki/Flood_myth). As mentioned, there might be more [water](http://www.sciencemag.org/content/344/6189/1265.abstract?sid=d573efc5-c389-4b1a-a4be-19fa8a3301de) trapped in the [mantle transition zone](http://en.wikipedia.org/wiki/Transition_zone_%28Earth%29), but it's hard to see how it could have slipped out to form liquid water, and even more difficult, how it could get back to the mantle, against gravity, after the flood.

However, as a homage to the Biblical believes, there could be an interesting link between sea level changes and mass extinction. Changing sea levels, especially when it happens rapidly, results in new conditions that species might not have time to [adapt](http://en.wikipedia.org/wiki/Adaptation) to. The connection is discussed in [this](http://www.sciencedirect.com/science/article/pii/S0012825299000550) article by Hallam and Wignall, 1999 ([Mass extinctions and sea-level changes](http://studentresearch.wcp.muohio.edu/extinctionsradiations/massextinctionsealevel.pdf)). The article is also a good example of scientific methods and reason. The language in a scientific article might not be so colorful as in Genesis, but it can open a world far more complex and wonderful than any dogma.

Finally, a reading tip:
One solution is proposed in Umberto Eco's [The Island of the Day Before](http://www.goodreads.com/book/show/10506.The_Island_of_the_Day_Before), maybe the water was borrowed from another day, as the Earth contains two days, separated by the [date line](http://en.wikipedia.org/wiki/International_Date_Line).

> **Comments:**
> **username_13**: Very good answer. I enjoyed learning from it.  
> **username_14**: @Tobbe  Excellent answer - Further, the cube figure you presented is quite a way to efficiently describe the overall earth water compartmentalization; I am curious if there exist a reference for this I would consider using this style of representation in a slide for courses or presentation (if it is permitted license-wise)  
> **username_4**: @fre0n A reverse Google image search found [the source for the image](http://en.wikipedia.org/wiki/Water_distribution_on_Earth#/media/File:Earth_water_distribution.svg). It's under the [Creative Commons BY-SA 3.0](http://creativecommons.org/licenses/by-sa/3.0/) licence so use in a presentation should be fine.  
> **username_5**: See also this answer for a more detailed discussion on changed sea levels: http://earthscience.stackexchange.com/a/2557/2536  
> **username_12**: Note that most of the Earth's water is not "in the Ocean", most water is in the Earth's interior. The cube diagram above is missing that. Check ref cited here: https://www.theguardian.com/science/2014/jun/13/earth-may-have-underground-ocean-three-times-that-on-surface , Of course, nobody knows of a mechanism to bring that water catastrophically to the surface  
> **username_5**: It is mentioned in the answer, if you read further. The water in the mantel is well known, but it's very difficult to estimate. At the moment a lot of interesting research is done to quantify the amount of water in the mantle.  

---

### Answer by username_4 on 2015-04-21. Score: 22

The "precipitation rate" part is easy to answer, at least to a first approximation. We have 40 days and nights (960 hours) in which to raise sea level above the peak of Mount Everest (let's round up and call it 9000m). Thus, we need a precipitation rate of around 9000/960 =~ 9.4 *metres* per hour. For comparison, the largest rainfall ever recorded over an hour is [305mm](http://en.wikipedia.org/wiki/List_of_weather_records#Rain). So a Noachian flood would require a precipitation rate over 30 times greater than the highest-ever recorded one-hour rate at a single site, sustained continuously over every point on the globe for the entire 40 days and nights.

> **Comments:**
> **username_8**: From Genesis 8:2, it seems there were 2 other sources of water in addition to rain: "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "  So there was water coming form "the deep" and well as from above.  http://www.mechon-mamre.org/p/pt/pt0108.htm  
> **username_4**: @username_8 Good point -- I suspect the "windows of heaven" might just be the supposed origin of the rain, but the "springs of the deep" (which are also mentioned in Genesis 7:11) can't be explained away so easily. But the question seems to be asking specifically for an equivalent precipitation rate, so I think this should be a sufficient answer. At the very least it could give us a baseline figure from which to estimate the required discharge rate from the "springs of the deep", whatever they may be (hydrothermal vents, perhaps?).  

---

### Answer by username_8 on 2015-04-22. Score: 5

> 1.Given the amount of water on Earth (including all the water as liquid, solid, and gas, in all possible places: the atmosphere, the surface, and underground), is there enough water to flood the whole earth until ‘all the high mountains… were covered’?

Yes. According to [Massive 'ocean' discovered towards Earth's core](http://www.newscientist.com/article/dn25723-massive-ocean-discovered-towards-earths-core.html)

> A reservoir of water three times the volume of all the oceans has been discovered deep beneath the Earth's surface.

Considering that the average depth of the ocean is 2.3 miles and the Earth is 71% water, three times this amount would be about the amount needed to reach the top of the highest mountains.

> 2.What is the estimated rainfall intensity based on this description, and how intense is it in comparison with today’s rainfall intensity in tropical areas?

There is no way to estimate rain fall from the description, because Genesis makes clear water came from "the deep" as well as from above. For example the passage qouted in the OP says "springs of the great deep burst forth" and Genesis 8:2 says "the fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained. "

> **Comments:**
> **username_5**: It's an interesting point, but the water in the transition zone is not water as we think about it in aquifers, something that is in contact with surface water and the oceans. It is rather a content of hydrogen and oxygen probably originating in subducted ocean crust. Schmandt et al 2014 talks about an extended water cycle, and the time frame is in the magnitude of Wilson cycles. We would need a good model for why all the 'water' in the mantle suddenly leaves the mantle and penetrate the crust. Even more difficult is to explain how the water suddenly would reenter the mantle, against gravity.  

---

### Answer by username_15 on 2015-04-22. Score: 2

Without requiring any rainfall, if you accept a theoretical scenario of a "dead Earth", meaning with no more active tectonics, no flux of heat from the mantle/core and given a long-enough time to almost completely erode mountains, then yes, a complete global flood may be possible. Just imagine to displace all the rocks that today are above the average sea level into the oceanic basins, then let them to compact (reducing porosity) and to reach isostatic equilibrium, pushing water above the sediments by density difference.

The thought experiment may then continue, calculating the average altitude of sediments and the average height of the water column above the surface in that case. A rough estimation should be in the order of a couple thousands meters of water above the global seafloor.

However I do not suppose that this may happen in 40 days, or anytime soon.


---

### Answer by username_16 on 2015-04-22. Score: -1

If you'll accept a much slower rain it could happen. Consider: As others have shown there is not enough water **on Earth** to do this. Since there's no feasible mechanism to get all the water on Earth into rain in the first place this isn't all that important anyway.

Instead, lets look elsewhere for the source of our rain: A large comet. It's captured by the Earth with the assistance of the Moon but it's in an orbit with a very low perigee. Comet stuff is shed, hits the atmosphere and comes down. Since it's mostly gas and ice you get rain, rain and more rain.

This can't happen in 40 days, though--there has to be enough time for it to cool. If that much water comes down in 40 days it's going to make Venus look positively arctic by comparison.

Thus it's possible for the Earth to become a waterworld like in the movie but not like in *Genesis*.

> **Comments:**
> **username_18**: The typical comet might have a thousand cubic kilometers of water.  Submerging Mount Everest requires about 4 400 000 000 cubic kilometers.  Bit of a difference there.  
> **username_16**: @username_18 Yeah, I said "large"--I realize the average one won't do it.  There are suitable bodies in the Oort cloud, though.  
> **username_18**: I believe Comet Hale-Bopp is the largest known comet.  If we take the upper bound for size estimate (40 km radius) and assume it's a sphere of pure water, that's still only about 200 000 cubic kilometers -- you'd need 22000 of them to flood the Earth.  
> **username_18**: As for Oort cloud bodies, if you assume it's pure water, you're looking for something at least 1100 km in radius -- something on a par with Pluto or Eris, and visually not much smaller than Earth's Moon.  We normally call these "dwarf planets", not "comets".  
> **username_16**: @username_18 I think your size is a bit off but I'll accept calling it a dwarf planet.  The basic idea is an extraterrestrial source, the size of the needed body is quibbling about details.  
> **username_10**: The problem with a comet, or comet-like larger body, is that it's going to come down with a heck of a bang.  Maybe not quite enough to splash off a second moon (see http://en.wikipedia.org/wiki/Giant_impact_hypothesis ), but I would think at least enough to melt the crust.  
> **username_16**: @username_10 A hit from a body that could deliver that much water would be an extinction event.  Note, however, that I am **not** figuring a hit, but rather orbital capture followed by a slow entry of the debris torn off by passing within the Roche limit.  
> **username_10**: @username_16:  It can't be that slow, though, since (according to the claim) the Flood happened in 40 days.  So at a minimum, you've got extreme atmospheric heating from the entry of that much mass - which can't enter at less than orbital velocity, at least in any way I can think of.  (And of course we're still left with the question of what happened to all that water afterwards...)  
> **username_16**: @username_10 Note my first sentence.  I'm saying a global flood (*Waterworld*) is possible but the *Genesis* version of such a flood is not.  
> **username_17**: @username_18, old question I realize, but you wouldn't need to flood the entire world by raising sea level that much.  You'd only need a storm surge maybe 10 miles high.  Displaced water causes floods.     There's enough water on Earth to flood the Earth, if you don't mind the flood being temporary.  (Most floods are temporary).   It would still take a gargantuan amount of energy though, a level 15 earthquake perhaps (which is probably impossible), or a meteor twice the size of the one that killed the dinosaurs (that would cause other serious problems in addition to a global tidal-wave).  
> **username_17**: A mantle plume under an ocean mgiht do it, theoretically.   Enough magma create a significant and permanent to boil in an ocean could fill the air with enough water vapor and make it rain for longer than 40 days and 40 nights, Melt the ice caps over time and not literally or completely, but in a practical sense, flood much of the Earth.  
> **username_16**: @username_17 That provides the 40 days and nights of rain, it doesn't flood the Earth in the process.  
> **username_17**: @username_16 true, but in combination with a really massive tsunami, much of the Earth could be flooded.   If the Chicxulub impactor had hit square in the pacific ocean, the tidal surge could have swept over the entire United States and Asia.   My point is that floods are usually temporary, not permanent changes in sea level, though they can be some of both.   The initial eruption of a mantle plume and super volcano might create a really big flood, and, followed by 40 days of rain.   It's still an improbable scenario.  I'm just thinking of ways it might happen without adding water.  

---

### Answer by username_19 on 2015-09-12. Score: -4

The primary source for the water that generated the flood was neither the upper mantle nor the atmosphere as rainfall, nor cometary bombardment or grazing, but earth's existing ocean water itself. Some water is liberated from the mantle in volcanoes and undersea vents, but these amounts are negligible except over very long periods of time.
Planet earth has a large amount of radioactive elements in its core and lower mantle. Radioactive element decay sequences, if they occur synchronized, could generate significant and rapid changes in the volume occupied by the elements, therefore, could rapidly change Earth's volume, same as a star can change volume in a collapse towards its core or in red giant phase but by a different process. If earth were to have shrunk, it would have displaced earths oceans to overwhelm the continents in wave after wave of tsunamis. If as the decay sequence continues, earths volume again increased, the water would have been displaced off the continents back into the ocean basins. No extra mystery water is needed to generate the flood, and no mystery as to where all the extra water went after the flood.
This radioactive decay would have generated massive heat, which would have shut off earth's protective electromagnetic field generating dynamo; however, an expanding earth would also create large rifts, and expose earth's mantle to the oceans, generating mass extinctions in the oceans, massive rainfall in equatorial regions, and massive blizzards at the poles; ergo, the ice ages; extreme cloud cover would have protected earth's life from cosmic rays till the dynamo turned back on; when the EMF turned back on centuries later, with rapid fluctuations, it seems to have generated a memory scrambling effect, recorded as The Tower of Babel event as the scrambling of languages.

> **Comments:**
> **username_20**: Nice that you mention *The Tower of Babel event as the scrambling of languages* at the end, because that is exactly what this [wall of text](http://uncyclopedia.wikia.com/wiki/Wall_of_Text) looks like. [Edit] your answer so that it is readable.  

---

