Thursday, July 11, 2013

Geological Movie Review of The Day After Tomorrow - Part 7

Geological Movie Review of The Day After Tomorrow - Overview

- Super Flooding -
- Starting off Slow -
NYC Flooding0:43:20 - As the movie moves along they continue to get more and more unrealistic. This includes the massive flooding along, apparently, everywhere in the northern hemisphere, including coastal lands from Nova Scotia to Florida. These are the only confirmed areas of flooding, but since they are flooding in such a variety of areas you can assume that most coastal areas of North America are affected as well.
   The flooding in the movie started with a "slow" rise in water seen through the sewer grates below some of the cars. Flooding in New York City is not unheard of. Hurricane Sandy in 2012 showed that NYC could easily be flooded to some extent. However, the movie at this point centers around the New York Public Library which is located at the corner of W 42nd St and 5th Ave. The elevation at this point is ~57 ft (FEMA) which is not super high (obviously) but it is significantly higher than most of the regions adjacent to the water. The library is located approximately equal distance from the East River and the Hudson River, where most of the flooding would come from. It is not even in the Category 4 Hurricane Flood Advisory (as pictured to the left) (
     The flooding in NYC is because the city is prone to storm surges, which is where the wind pushes the water against the shore. It is not an increase in the actual water level from normal, just an increase in the local water level. If it is high tide, like it was for Hurricane Sandy, then the water has a higher starting point from which the storm surge can flood from. But assuming a "normal" storm, or even a large hurricane category 4 storm, the water level would not even be close to reaching the library as can be seen on the map to the right (light blue is category 4 storm surge).
- Nova Scotia Waves -
0:43:53 - Following the flooding in NYC, flooding is mentioned in Nova Scotia. Since it is along the eastern shore of North America, we can assume that the flooding in Nova Scotia and NYC are tied to the same storm surge event. Statue of LibertyIn Nova Scotia, it was mentioned that the "ocean rose by 25 feet in a matter of seconds". Assuming that this is broadcast media sensationalism, let us take it as a large wave that over took the island. If we look at wave heights for Hurricane Sandy, it was recorded that they reached a record 32.5 feet before hitting land (Climate Central). Given waves of this height for a Category 1 hurricane, it is easy to believe that Nova Scotia could be inundated by waves of 25 feet with a far larger storm.
- Tsunami? -
0:48:06 - We are now entering into what is getting to be really unbelievable. We are shown what could only be considered a ~240 foot tsunami cresting the Statue of Liberty. A tsunami is generated from something like an earthquake or a volcanic eruption, both of which can displace large quantities of water or land (by moving land you move the water on top of it). Nothing in the movie has indicated any such event as happening. A storm surge is strong at times but there is definitely not enough wind power to generate such a strong wave. That and the wind power would need to be ramped up suddenly causing such a tsunami to form, otherwise it would just be a gradual storm surge increase. Also, immediately following a normal tsunami, the water rapidly retreats due to the imbalance that is caused with the water being at a higher elevation then what gravity will allow it to be, so most of the water will return to the sea. This is contrary to the movie where not only does the water not retreat, it rises. Which, is indicative of a storm surge. In a storm surge, the water will remain on land as long as the wind providing the force to keep it there remains strong. On a side note, the water level did decrease from the ~240 feet at the Statue of Liberty to ~100 feet when it hit the library.

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