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Using Googlemaps To Simulate Tsunamis

timothy posted more than 3 years ago | from the you're-all-wet dept.

Earth 40

flemster writes "Tsunami mapper is a new site which uses the googlemaps elevation service and the flood fill algorithm to predict which areas near a coast are likely to be affected by a tsunami. You can search for your local beach, set a wave heading and height and then double click the tsunami starting point off the coast, after which the tsunami range will be drawn. Naturally, predicting a tsunami is far more complicated than this and this application is a general guide and not a true predictor. However the simulations of the recent Japanese simulation are interesting. Compare the tsunami mapper simulation with this aerial photo of Ishinomaki after the March tsunami."

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Didn't work... (3, Insightful)

SIGBUS (8236) | more than 3 years ago | (#35986266)

"Elevation of starting location is 158.171 meters. A tsunami must start in the ocean."

Then again, I was trying to create a tsunami on Lake Michigan.

Re:Didn't work... (1)

maxwell demon (590494) | more than 3 years ago | (#35986314)

I couldn't get it to work in the ocean, either. I always got told that my tsunami didn't reach land.

Re:Didn't work... (1)

Ziekheid (1427027) | more than 3 years ago | (#35986350)

Same here, no matter what location in the ocean I tried.

Re:Didn't work... (0)

Anonymous Coward | more than 3 years ago | (#35986416)

TACO!!!!!

Actually sortof works (-1, Flamebait)

MickLinux (579158) | more than 3 years ago | (#35986458)

Okay, it appears after looking at the simulation and then the actual flooding, that the program works best on mountainous islands.

The bright blue is the "flooding" area.

That said, the program appears to ignore wave height: the flooding area is the same for 10m and 5000m. Or more likely, it only checks the nearest surrounding kilometer.

Likewise, even if it shows the land flooding in (say) the Elizabeth River, it says that the tsunami didn't reach land: I guess that stuff that registers as "zero elevation" is not considered land, regardless.

Re:Didn't work... (3, Informative)

camperdave (969942) | more than 3 years ago | (#35986440)

They only simulate it for about 10 km, regardless of how high the wave is. I am severely disappointed in this simulation.

Re:Didn't work... (2)

LordKronos (470910) | more than 3 years ago | (#35986574)

I agree. I was hoping to see the result of a 1km wave purely for amusement (or maybe to prepare for a future meteor impact in the ocean). I was severely disappointed. Also, it seems that 1000 meters is some strange cutoff point, as that actually shows less flooding than 999 meters.

Re:Didn't work... (0)

Anonymous Coward | more than 3 years ago | (#35986560)

It is an exercise in desensitizing people to tsunami by appealing to their God complexes. It is no accident, we can expect tsunami incidences to rise due to clandestine man-made underwater nuclear explosions.

The purpose of it, of course, is to provide work for land developers and other contractors who make a living building luxury hotels, beachside resorts, and McMansions along the coastline. The tsunami kills two birds with one stone - it displaces the existing middle-class inhabitants and helps level the existing properties, clearing the way for perks only the uber-rich can afford. It is the same principle for invading and destroying Iraq so billions of dollars could be allocated to overpriced reconstruction and security services via contractor.

Re:Didn't work... (1)

TheClarkster (1130495) | more than 3 years ago | (#35986622)

Haha, you almost had me there. Thought you were serious for a while.

Re:Didn't work... (3, Informative)

Ol Biscuitbarrel (1859702) | more than 3 years ago | (#35986424)

I also like "It's best to start the tsunami a few kilometers from the shore." This in reference to the tsunami not reaching Aberdeen Washington, no matter where I start them from. Maybe the coders are into Nirvana?

Would help to add a scale so we can figure how much map covers those few kms, too...

OK, after looking at the Gallery I think they meant meters, not kilometers - you doubleclick right offshore to mark where, uh, the news crews will congregate? Wave fronts are a bit more diffuse than that, I believe.

Re:Didn't work... (1)

maxwell demon (590494) | more than 3 years ago | (#35986470)

OK, after looking at the Gallery I think they meant meters, not kilometers - you doubleclick right offshore to mark where, uh, the news crews will congregate? Wave fronts are a bit more diffuse than that, I believe.

Thanks for the hint. I now can create tsunamis as well. And I learned that even kilometer high tsunamis won't go very far. ;-)

Re:Didn't work... (2)

camperdave (969942) | more than 3 years ago | (#35988916)

Here's how it works. Pick a point of 0 elevation. Check the surrounding ten by ten km square (adjusting for "wave direction"). For each 1km by 1 km square in the area, if the elevation is less than the wave height, paint it blue.

Re:Didn't work... (1)

ultranova (717540) | more than 3 years ago | (#35991214)

Here's how it works. Pick a point of 0 elevation. Check the surrounding ten by ten km square (adjusting for "wave direction"). For each 1km by 1 km square in the area, if the elevation is less than the wave height, paint it blue.

In other words, this so-called "simulation" is absolutely worthless.

Re:Didn't work... (1)

mpe (36238) | more than 3 years ago | (#35990014)

"Elevation of starting location is 158.171 meters. A tsunami must start in the ocean."
Then again, I was trying to create a tsunami on Lake Michigan.


Maybe the model they are using dosn't allow for impact generated tsunamis. Is water density also a factor. I suspect the water depth is more relevent than its elevation too.

Doesn't work for the great lakes (0)

Anonymous Coward | more than 3 years ago | (#35986270)

Bummer

honesty/sense used mapping end of cataclysms (0)

Anonymous Coward | more than 3 years ago | (#35986288)

resulting in a much friendlier (like it was a few years ago) place to live. it's beginning to appear that we're far from indestructible, & currently our own worst enemies, again. there is going back. disarm. thank you.

hymenology counsel; there's one born every minute (0)

Anonymous Coward | more than 3 years ago | (#35986984)

but there's no way to know which minute that thing appeared, until the investigations are completed.. god's little gatekeeper. is that cruel? remember, endless suffering prior to dying for the love of fictional characters, is our promised reward? we weren't born with any ability or intention to hate or kill each other either. that must've come from the queers who have been bequeathed with an almost agnostic (knows no bounds) form of hatred by groups of man'kind', expressing the fear we were never trained to express appropriately.

In the US they are called... (0)

Anonymous Coward | more than 3 years ago | (#35986332)

sue nami and are in fact frivolous soaps.

Re:In the US they are called... (0)

Anonymous Coward | more than 3 years ago | (#35986478)

How many could goatse fit in his ass?

Incredible application (1)

Stiletto (12066) | more than 3 years ago | (#35986412)

Oh my god, when you select "West" it draws a blue square to the west of where you clicked, and when you select "East" it draws a blue square to the east. That's incredible. This must have taken five PhDs 2 months to make.

Re:Incredible application (0)

Anonymous Coward | more than 3 years ago | (#35986546)

Actually 10 PhDs, and it took us 2 years to make, it was our Dissertation. All 10 of us were granted degrees.

Re:Incredible application (1)

smitty97 (995791) | more than 3 years ago | (#35986664)

WOW, you GOTTA try NORTH-EAST!!!!!1!one

Flood fill... (0)

Anonymous Coward | more than 3 years ago | (#35986528)

is what a tsunami does.

Earthquake Simulation (0)

Anonymous Coward | more than 3 years ago | (#35986584)

Open an image of your favorite country and hold F11.

Re:Earthquake Simulation (0)

Anonymous Coward | more than 3 years ago | (#35987354)

It this the "it goes to 11 moment"? And, Yes, what everybody else said, It Doesn't WORK and it's a POS. Tried it at my brother's house on the Oregon coast, hoping it would wash him and his bitch of a wife in the sea, No Joy.

unable to use for Wyoming (0)

Anonymous Coward | more than 3 years ago | (#35986912)

I wanted to see what size of tsunami would be necessary to get to my house in Wyoming at 2265 meters elevation above sea level, but the tool seems unable to answer that question.

It's not the size, it's the motion of the ocean. (1)

blair1q (305137) | more than 3 years ago | (#35986950)

I didn't try it, but could someone who did confirm that it knows jack squat about energy?

A "5-meter" tsunami is going to go halfway up a 500-meter cliff if it retains enough energy.

Re:It's not the size, it's the motion of the ocean (1)

ultranova (717540) | more than 3 years ago | (#35991284)

I didn't try it, but could someone who did confirm that it knows jack squat about energy?

It doesn't. As the summary says, it's a flood-fill algorithm - it works like the paint bucket in an image editor, where the flood-stop condition is "elevation >= wave height". Oh, and it only checks a few kilometers worth of land at a time.

A "5-meter" tsunami is going to go halfway up a 500-meter cliff if it retains enough energy.

No, because tsunami (like any wave) is a wave, not flow. A 5-meter tsunami is 5 meters high because it has just enough energy to pile water that high when the front starts decelerating near the shore. In a way, it already has gone up a cliff as high as it can; the back parts have piled on top of the front ones.

Or so I've understood, anyway.

Re:It's not the size, it's the motion of the ocean (1)

blair1q (305137) | more than 3 years ago | (#36003610)

No, a tsunami is a longitudinal body wave in the horizontal displacement of the medium. An ordinary wave is a transverse surface wave in the height of the medium.

The height of an ordinary wave is most of the energy involved, no matter how deep the water. You cause them by blowing on the surface of your bathtub.

The height of a tsunami is only a tiny indication of the total energy involved; it's not even proportional when the depth is accounted for. It's like moving your entire bathtub back and forth.

A tsunami is very much a flow. First in, then out. The flowing observed on the shoreline for ordinary waves is just a degeneration of their circular surface motion.

That's why 5-meter waves are fun for surfing and impressive to stand and watch from the shore, but a 5-meter tsunami is a historical monster that you'd better run several kilometers inland to avoid.

There are fjords in Canada that show scarring hundreds of feet up one side from a tsunami caused when a big piece of the slope on the other side broke off and fell into the water, stripping everything loose (vegetation, rocks, dirt, etc.) on its way up the impact side. That's a tsunami that has enough energy.

It is as I feared (1)

RogerWilco (99615) | more than 3 years ago | (#35987362)

My country is doomed!

It doesn't want to start a wave if the elevation is above 2 meters. Well, about 60% of my country, The Netherlands, is below that magic number.
Everywhere I click that's below 2 meters just generates a 10x10 km blue square, so I suppose that's flooded. I took a 20meter tsunami and traced the 2 meter line in my country, having the tsunami travel south-east mostly. Then the blue squares are not entirely filled in, the "water" only flows until it hits things above 20 meters.
So basically what this application does, is draw blue squares for anything below the set height above sea level.

For 20 meters, that's about 70% of my country. It reaches as far inland as Eindhoven, Utrecht, Deventer or Assen. Cities like Amsterdam and Rotterdam disappear completely.

Fortunately tsunami's in the North Sea are rare, only once in about 10.000 years. If they do occur they seem to be quite devastating according to archaeological records though, google for Doggerland. It's an area about the size of Ireland or Colorado that was washed away in the last known tsunami, in about 5000 B.C.

The next tsunami to occur in the North Sea might kill as many as 10 million people, it would reach the Houses of Parliament in London and places like Amsterdam, most of the Netherlands, Bremen and Hamburg would be completely wiped of the map probably.

Don't worry (1)

Anonymous Coward | more than 3 years ago | (#35987552)

The Doggerland tsunami hypothesis is at present just that, a hypothesis. IANAA (nor a P or a G) but as I understand it there are problems with the hypothesis that are still to be resolved. Even so, if tsunami in the North sea come by every 10.000 years or so and the last one was about 8000 years ago, then that might be too close for comfort. So, how are we doing?
Even though self-proclaimed paragnosts and spirituals predict that the Netherlands will be hit by a tsunami every other year, so far the North Sea has proven pretty calm. The reason is that the current plate tectonical situation isn't likely to cause a tsunami.
But if one were to occur? The present geology of the North Sea is such that the tsunami would lose much energy due to various islands and dissipating coastlines further to the north. All the while it would be travelling over a very lightly sloping seabed, which means that the waves cannot build up to the enormous height as they did in Japan and hence cannot overcome the Deltaworks.

Re:It is as I feared (1)

Daniel Dvorkin (106857) | more than 3 years ago | (#35987916)

AFAIK Doggerland was mostly just submerged by rising sea levels at the start of the current interglacial period; the remaining bits of it may have been washed away by a tsunami, but most of it was already underwater. I'm not arguing with your contention that a North Sea tsunami would be devastating, just pointing out that describing Doggerland as "an area about the size of Ireland or Colorado that was washed away in the last known tsunami" is a bit of an exaggeration.

Misread the title ... (1)

Alain Williams (2972) | more than 3 years ago | (#35989314)

Using Googlemaps To Stimulate Tsunamis

Phew! ...

Re:Misread the title ... (1)

1u3hr (530656) | more than 3 years ago | (#35989456)

Product placement for Lex Luthor's next real estate plot.

A note from the author... (1)

flemster (600506) | more than 3 years ago | (#35989694)

Thanks for the feedback. A couple of points:
1) Yes - you do need to set the direction before clicking on the map. Otherwise the wave will go in the wrong direction and the results will be bad.
Next release (give me 24 hours) will force the user to enter a direction and also put a little arrow showing the direction chosen.

2) Yes - the flooded area can only be 10km by 10km. I chose this based on some basic research on tsunami reach and needing a reasonable response time from google's elevation service.

3) Yes - it only uses flood fill algorithm to determine if an error is blue or not. If the elevation of the location is less than the wave and it has a neighboring sector which is blue, then its blue.
If someone can point me to the maths that describes how to calculate this based on the wave's energy, velocity etc then I'll have a try. But there may be a limit to what can be done in 300 lines of JavaScript :-)

Re:A note from the author... (1)

bananaendian (928499) | more than 3 years ago | (#35991642)

Perhaps you could've slightly improved your piece of 'code' before slashing it here, but then anything get plastered around here these days...

Google maps DEM (Digital Elevation Model) is based on SRTM [nasa.gov] (Shuttle Radar Topography Mission) data over most of the globe. You can download [usgs.gov] the original processed data from NASA and apply it to any GIS software [opensourcegis.org] of your choice.

Then with a single click of the elevation tool you can raise or lower the global sea level by x meters of your choice. Was playing around with this 7 years ago when the data came out. Now bored of it.

Like some have pointed out already, the flood fill algorithm is a bit pointless since tsunamis don't behave like flood filled algorithms. A more informative map would simply color areas more than a certain height green showing areas that are definitely out of reach of a tsunami of certain height. Then people could at least see where its relatively safe by inputting the maximum wave height. With large tsunamis we do not even have scientific data on how far inland they could actually travel. Some geologists for example speculate that a super tsunami might have swept across the whole of the Australian continent.

Re:A note from the author... (1)

Askmum (1038780) | more than 3 years ago | (#35997434)

3) Yes - it only uses flood fill algorithm to determine if an error is blue or not. If the elevation of the location is less than the wave and it has a neighboring sector which is blue, then its blue. If someone can point me to the maths that describes how to calculate this based on the wave's energy, velocity etc then I'll have a try. But there may be a limit to what can be done in 300 lines of JavaScript :-)

Then I have a far easier solution. Find and show an overlay with 1 meter increments and you know what a tsunami does in your simulation. IMHO your solution is only good as a programming excercise, not as anything worth showing the world.

As one of the previous commenters I also live in the low country and I would be very interested to see what a tsunami does. To limit it to 10x10 km means it does not show anything. I'm 15 meters up and 150 km inland. What does a 20 meter tsunami do to me?

But will there be a red dot... (0)

Anonymous Coward | more than 3 years ago | (#35989730)

...with emanating glowing circles?

http://youtu.be/8wHMaJ6AtNs

Absolutely... (1)

pigiron (104729) | more than 3 years ago | (#35991146)

lame simulation.

In summary... (1)

flemster (600506) | more than 3 years ago | (#36061486)

Thanks everyone for their feedback. Nothing like getting slash-dotted for finding out what the world thinks.

Now that its off the front page, I'm going to to take the opportunity to get the last word.

Few more points:
1) In the initial description it does say "... this application is a general guide and not a true prediction" and so yes I agree flood fill isn't the most accurate algorithm for predicting tsunamis. More accurate is GeoClaw [washington.edu] which has a lot of fortran and phython code and some very detailed wave models - but obviously its not easy to incorporate into a simple Applet like mine.

2) IMHO, flood fill is better than simply testing the elevation of all points against the wave cause it prevents the water moving through mountain ranges. The logic for flood fill is very simple (maybe 100 lines of code) and its a small extension to basic elevation testing we can handle.

3) Keep watching the web site, cause I do have some improvements planned. Namely handling more than a 10km by 10km area and taking what we do map down to lower level of detail. But for the algorithm I'll probably be sticking with flood fill at least in the short term.

Finally, if someone is bored I am open to collaboration - in particular to with regard to point 1 above, I'm sure someone with the right knowledge could make a much better algorithm. Check the site for email address.
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