# If everyone on earth suddenly disappeared, what would happen to Boulder (Hoover) dam? **URL:** \ **Category:** Factual Questions\ **Created:** [May 23, 2009, 9:11pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422 "2009-05-23T21:11:57Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Early\_Out](https://avatars.discourse-cdn.com/v4/letter/e/6f9a4e/32.png) [@Early\_Out](https://boards.straightdope.com/u/Early_Out)\ **Post date:** [May 24, 2009, 9:42pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/21 "2009-05-24T21:42:47Z")
> [@Markxxx](#): > > … changing the name of Boulder Dam To Hoover Dam… And just to add to the fun, the dam was built in Black Canyon, not Boulder Canyon, which was about 8 miles upstream. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 24, 2009, 10:05pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/22 "2009-05-24T22:05:41Z")
> [@Early\_Out](#): > > Those were probably all earthen dams. Hoover is concrete, as wide at the base (I mean front to back, not side to side) as it is tall, so I don’t think the cascading water would erode the face of the dam to any appreciable degree. The failure of concrete dams is often associated with foundation movement (failure of bearing soils, earthquake, overturning failure of monolithic sections) rather than overtopping. I agree that overtopping of Hoover Dam isn’t quite the emergency that it is for earthen dams. For example, the [St. Francis dam](http://en.wikipedia.org/wiki/St._Francis_Dam#Prelude_to_disaster) (a concrete gravity arch dam) failed due to instability of the underlying geology. I imagine that the USBR has considered the case of overtopping of Hoover Dam but I suspect they’re keeping that info to themselves. ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [May 25, 2009, 1:00am UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/23 "2009-05-25T01:00:23Z")
> [@NinetyWt](#): > > The failure of concrete dams is often associated with foundation movement (failure of bearing soils, earthquake, overturning failure of monolithic sections) rather than overtopping. I agree that overtopping of Hoover Dam isn’t quite the emergency that it is for earthen dams. > > For example, the [St. Francis dam](http://en.wikipedia.org/wiki/St._Francis_Dam#Prelude_to_disaster) (a concrete gravity arch dam) failed due to instability of the underlying geology. > > I imagine that the USBR has considered the case of overtopping of Hoover Dam but I suspect they’re keeping that info to themselves. The case of the [Vajont Dam](http://en.wikipedia.org/wiki/Vajont_Dam) in Italy provides an interesting example, though it’s not nearly the same thing because it was overtopped by an enormous 800-foot wave caused by a catastrophic landslide into the reservoir the dam had created. As the Wikipedia article points out, “the dam’s structure was largely undamaged — the top metre or so of masonry was washed away, but the basic structure remained intact” and “a pumping station was installed to keep the lake at a constant level, and the bypass gallery was later lengthened beyond the dam to let the water flow down to the Piave valley. The dam is being maintained and is still in place, unaffected by the tragedy…” A frickin’ instantaneous wave 800+ feet high, containing 50 million cubic meters of water, hit the dam all at once, and it only took off the top meter of the dam. Of course, this doesn’t tell us much about what would happen over the long haul – how erosive would a slow and steady waterfall over the top of the dam be versus a single enormous event? But it does suggest that it probably wouldn’t result in immediate failure, at least. ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [May 25, 2009, 2:07am UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/24 "2009-05-25T02:07:25Z")
> [@chorpler](#): > > The case of the [Vajont Dam](http://en.wikipedia.org/wiki/Vajont_Dam) in Italy provides an interesting example, though it’s not nearly the same thing because it was overtopped by an enormous 800-foot wave caused by a catastrophic landslide into the reservoir the dam had created. As the Wikipedia article points out, “the dam’s structure was largely undamaged — the top metre or so of masonry was washed away, but the basic structure remained intact” and “a pumping station was installed to keep the lake at a constant level, and the bypass gallery was later lengthened beyond the dam to let the water flow down to the Piave valley. The dam is being maintained and is still in place, unaffected by the tragedy…” > > A frickin’ instantaneous wave 800+ feet high, containing 50 million cubic meters of water, hit the dam all at once, and it only took off the top meter of the dam. Of course, this doesn’t tell us much about what would happen over the long haul – how erosive would a slow and steady waterfall over the top of the dam be versus a single enormous event? But it does suggest that it probably wouldn’t result in immediate failure, at least. The first cite in the Wiki Vajont article is well worth downloading (more or less a pdf-based slideshow): [http://tellnet.jp/pdf/italy.pdf](http://tellnet.jp/pdf/italy.pdf) Thanks for that link. Fascinating. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 25, 2009, 2:34am UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/25 "2009-05-25T02:34:10Z")
> [@chorpler](#): > > how erosive would a slow and steady waterfall over the top of the dam be versus a single enormous event? The depth of erosion resulting from a single event theoretically depends upon the composition of the concrete, the shape of the dam crest, and the depth of the water passing over the crest. It can be calculated. The time it takes to erode away is a function of the cohesiveness of the material. I don’t think that a single event would have time to erode the entire Hoover Dam away. Eventually, of course, the dam would erode away to the river bottom, since the water will keep eating away at it 24/7. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [July 13, 2009, 4:48pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/26 "2009-07-13T16:48:43Z")
> [@](#): > > Gracie) That’s what I mean, instead of changing the name of that great big dam, it would’ve been much easier to change the name of a little man. > > George) Oh I see…Change Herbert Hoover’s name to Hoover Boulder Then we would have had a precedent when President Canaveral was assassinated. ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [July 13, 2009, 7:36pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/27 "2009-07-13T19:36:28Z")
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