# Can New York be evacuated in the event of a megatsunami? **URL:** \ **Category:** Factual Questions\ **Created:** [December 27, 2004, 4:27am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741 "2004-12-27T04:27:36Z")\ **Posts on this page:** 12\ **Page:** 4
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [December 28, 2004, 10:09pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/61 "2004-12-28T22:09:01Z")
> [@GusNSpot](#): > > IMO, if I was in NYC when the alert sounded, I would steal a small boat and head straight out to the deepest water I could get to. Off shore, the wave is just a hump of water and without special instrumentation you would never know it went under you. Shallow water is the problem. This is not a rogue storm wave but a tsunami . Two different things… > > YMMV I think my best option would depend on where I happened to be at the time the warning sounded. If I was at home (in Hoboken) I think scrambling up the Heights to Jersey City would be the best bet (probably at least 100 ft elevation difference). At work, probably just hang out on one of the top floors of my Midtown office and hope it doesn’t topple. Another option would be to hijack the Hoboken ferry and take it out to deep water. ---
**Author:** ![El\_Cid\_Viscoso](https://avatars.discourse-cdn.com/v4/letter/e/41988e/32.png) [@El\_Cid\_Viscoso](https://boards.straightdope.com/u/El_Cid_Viscoso)\ **Post date:** [December 28, 2004, 10:12pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/62 "2004-12-28T22:12:25Z")
> [@aerodave](#): > > We still haven’t gotten a very satisfactory answer to this question. On the contrary. I answered this question yesterday. Recent simulations say the wave could reach around 12-15 miles inland. 🙂 Since you might’ve missed it, there are some good links in my earlier post. In my opinion, the most interesting is the projection of the La Palma shock wave, and how it curls across the expanse of ocean in 6-8 hours… > [@](#): > > “It would be something like every single sector of the eastern coast being devastated by a category five hurricane simultaneously,” predicted Dr Simon Day from the Benfield Centre at University College London. > [@](#): > > Initially the wave would be around 650 km high, according to research models. > > It would lose height as it moved across the ocean, but would still be around 50 m tall by the time it crashed into the United States. Depending on local topography its [impact could be felt up to 20 km inland](http://www.benfieldhrc.org/SiteRoot/in_the_news/press_cuttings/Insurance%20Day/new_york_tsunami.htm). ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [December 29, 2004, 12:08am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/63 "2004-12-29T00:08:34Z")
> [@](#): > > Initially the wave would be around 650 **km** high :eek: ---
**Author:** ![aahala](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@aahala](https://boards.straightdope.com/u/aahala)\ **Post date:** [December 29, 2004, 12:33am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/64 "2004-12-29T00:33:26Z")
> [@aerodave](#): > > :eek: This is Houston, Space Shuttle, you’ve got a problem.😃 ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [December 29, 2004, 1:04am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/65 "2004-12-29T01:04:18Z")
> [@msmith537](#): > > Another option would be to hijack the Hoboken ferry and take it out to deep water. You think so? You’re going to hijack an open-sided boat with a top speed of 12 - 15 mph to get down the Hudson and out across 100 miles of ocean (since you need to get past the Continental Shelf) before this super wave makes it across the Atlantic at several hundred miles an hour? I hope you luck is better than my luck. (Even Gus is going to have to hope he can find a cigarette boat tied up in downtown NYC.) ---
**Author:** ![El\_Cid\_Viscoso](https://avatars.discourse-cdn.com/v4/letter/e/41988e/32.png) [@El\_Cid\_Viscoso](https://boards.straightdope.com/u/El_Cid_Viscoso)\ **Post date:** [December 29, 2004, 2:22am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/66 "2004-12-29T02:22:33Z")
> [@aerodave](#): > > :eek: Ouch. What a typo. 😃 ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [December 29, 2004, 2:29am UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/67 "2004-12-29T02:29:10Z")
> [@Whack-a-Mole](#): > > I was in Chicago for both of these events as well (I was in the Loop both times) and indeed the area (Loop again) did empty out in good order. There were large backups at the trains and so forth as the mass transit system was not set in evening rush hour mode yet so clearing everyone out took some time but it all got sorted out with little trouble. I don’t know about your train (I’m on the South Shore South Bend electric) but for 9/11 they were just pulling the trains up, loading, then sending them out - _totally_ not the normal schedule, but as you said, folks waited their turns. For the Tunnel Flood I was taking the bus and El, which run frequently anyway (at least it did back then) so while the trains and buses were packed nothing special was required to keep the vehicles coming. > [@](#): > > However, the key here I believe is the total lack of panic on the part of people leaving the city. The “flood” was weird because it was totally out-of-sight and certainly posed no imminent danger to people. For 9/11 people were shaken and worried but no one I am aware of felt death was near. I think the prior experience with the Tunnel Flood was also a factor - I remember a lot of people on 9/11 recalling _that_ evacuation, so in a sense you had a large number of people who had been there before, had some idea how all this would work, and the concept wasn’t completely new. There was a certain trust we _could_ move tens of thousands of people out of the busines district in just a couple hours without problems. One bad incident _could_ have precipitated a panic on 9/11 - a lot of people were on the edge because all we really knew at the time was that tall buildings in big cities were being targeted, and Chicago has five of the ten tallest buildings in the world. Yeah, that’s another thing - on 9/11 it was a _spontaneous_ exodus. No one official ever called for an evacuation, it’s just that 100,000 people all simultaneously decided they wanted to be someone else, got up, and left. You didn’t have to broadcast or disseminate information to the public at large, the public already knew and no one questioned that reducing the number of people in the immediate area was a good idea. > [@](#): > > Further, in both instances you cite, they just cleared out the Chicago Loop (main business district in Chicago) which, while holding a lot of people during the business day, is still only a small fraction of the city. In the event of such a natural disaster heading our way you’d have to clear out a great many more people than just those in the Loop. Very true - you can pull maybe a 100,000 out of a city like Chicago in a couple hours… but Chicago has 3,000,000 in the city as a whole. You can save a lot of people, but you’ll lose even more, LOTS more, than you’ll save. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [December 29, 2004, 3:13pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/68 "2004-12-29T15:13:16Z")
> [@tomndebb](#): > > You think so? You’re going to hijack an open-sided boat with a top speed of 12 - 15 mph to get down the Hudson and out across 100 miles of ocean (since you need to get past the Continental Shelf) before this super wave makes it across the Atlantic at several hundred miles an hour? Would you have to get a boat past the Continental Shelf to be safe? I cannot find depth charts online (unless I want to buy them) but my sense has always been you could get a few hundred feet of water under you by not going all that far from shore (I know shoals and such might rise here and there but broadly speaking). Granted a Megatsunami of epic proportions might well start rising in 400 feet of water but at that point wouldn’t it be more like the whole ocean rising than a breaking wave that would tip the boat? Or even a monster swell but still one that a boat could ride over? I am honestly asking as I really have no clue what I would expect to see sitting in 400 feet of water a few miles offshore with a megatsunami hurtling at me (and hope I never do). ---
**Author:** ![sunfish](https://avatars.discourse-cdn.com/v4/letter/s/96bed5/32.png) [@sunfish](https://boards.straightdope.com/u/sunfish)\ **Post date:** [December 29, 2004, 4:44pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/69 "2004-12-29T16:44:59Z")
[This is not the greatest bathymetric map of the New York Bight region,](http://oceanexplorer.noaa.gov/explorations/02hudson/background/mapping/media/elevation.html) but it is the best I can find at the moment without a rotated view or vertical exaggeration. Note that you have to go out pretty far - nearly a hundred miles or so in most cases - to reach water more than 300 feet (~92 m) in depth (the lightest blue shading), and more than that to reach the boundary between the very gently sloping shelf and the steep sloping continental slope (darker shades of blue indicating 500+ feet (~154 m) depth, bounded by the near-black abyssal plain). The continental slope itself is extremely narrow here in comparison to the shelf. Whatever the size of the tsunami is in the open ocean, once it reaches the edge of the continental slope, its speed rapidly decreases and height increases. That’s because the bottom of the wave begins to drag on the sea floor, so the energy of the wave is compressed and the water is pushed up. When this process happens quickly (e.g., with a steep, narrow continental slope), the wave will break. In the case of our tsunami, that wave breaking is not going to prevent the wave from heading further shoreward and causing more havoc (although the shallow slope of the continental shelf will rob it of some energy through friction). Even if we assume that the tsunami on the open sea is “surfable,” I sincerely doubt that any ship would survive an encounter once the wave hits the continental slope, builds and breaks, so you would _have_ to try for the open ocean and its enormous swells… which could still be in excess of 150 feet (~50 m), as per **El Cid Viscoso’s** cite. Personally, I think I would rather run like hell inland rather than try the ocean route. 🙂 > [@Whack-a-Mole](#): > > I am honestly asking as I really have no clue what I would expect to see sitting in 400 feet of water a few miles offshore with a megatsunami hurtling at me (and hope I never do). Have you seen _The Perfect Storm_? The fishing boat _Andrea Gail_ is thought to have been swamped by a 100-foot wave during that storm, and the movie shows how that might have happened. Yes, it’s all CGI but… damn. Just damn. It would give you a little taste of what to expect, I think. ---
**Author:** ![av8rmike](https://avatars.discourse-cdn.com/v4/letter/a/edb3f5/32.png) [@av8rmike](https://boards.straightdope.com/u/av8rmike)\ **Post date:** [December 30, 2004, 4:03pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/70 "2004-12-30T16:03:14Z")
> [@wolfman](#): > > and judging by the spelling of tons, i’m guessing it might actually be 500 _trillion_ tons U.S.-speak. > > gald I could make you feel better. 🙂 No. A “[tonne](http://www.unc.edu/~rowlett/units/dictT.html#tonne)” is the same as a metric ton in the SI system, or 2204.6 pounds, or only about 10% larger than a U.S. ton. Not that it makes much difference when you’re talking about 500 billion of them. ---
**Author:** ![aahala](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@aahala](https://boards.straightdope.com/u/aahala)\ **Post date:** [December 30, 2004, 4:16pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/71 "2004-12-30T16:16:27Z")
> [@av8rmike](#): > > No. A “[tonne](http://www.unc.edu/~rowlett/units/dictT.html#tonne)” is the same as a metric ton in the SI system, or 2204.6 pounds, or only about 10% larger than a U.S. ton. > > Not that it makes much difference when you’re talking about 500 billion of them. wolfman’s comment probably has to do with “trillion”. Tonne is not a term used often in the US, so it’s not likely an American trillion but six additional zeroes on the right. ---
**Author:** ![aahala](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@aahala](https://boards.straightdope.com/u/aahala)\ **Post date:** [December 30, 2004, 4:21pm UTC](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741/72 "2004-12-30T16:21:05Z")
> [@aahala](#): > > wolfman’s comment probably has to do with “trillion”. Tonne is not a term used often in the US, so it’s not likely an American trillion but six additional zeroes on the right. I must have thrown that trillion in just to make it harder. . .Billion is a different number on each side of the Atlantic as well.😃 [Previous page](https://boards.straightdope.com/t/can-new-york-be-evacuated-in-the-event-of-a-megatsunami/281741.md?page=3)