Martian what?

[PB666]

http://www.bbc.com/news/science-environment-36333760

 

[insert_name]

Cool, Martian ice tsunami, too bad it happened so long ago, it would have been cool to get footage of that 

[SargeRho]

Well, we already knew that Mars once had large standing bodies of water, so this isn't a big surprise.

[PB666]

3 minutes ago, SargeRho said:

Well, we already knew that Mars once had large standing bodies of water, so this isn't a big surprise.

It seems like a insane conclusion to me, tsunamis on a world that barely had water, isn't there a more conservative conclusion?

[Ten Key]

This is well outside my wheelhouse, but. . .it doesn't take that much water to support a tsunami, does it?

http://www.nature.com/news/ancient-tsunami-devastated-lake-geneva-shoreline-1.11670

[sevenperforce]

Mars had a good deal of water. And you only need water 500 m deep to make a 500 meter high tsunami.

Most of the water on Mars escaped into space because its gravity is a touch low. 

[kerbiloid]

1 hour ago, PB666 said:

It seems like a insane conclusion to me, tsunamis on a world that barely had water, isn't there a more conservative conclusion?

Just try to stay in a rainy day near a road where cars are going there and back.

Soon you'll see that tsunami is possible even in a inch-deep pool.

[PB666]

6 hours ago, kerbiloid said:

Just try to stay in a rainy day near a road where cars are going there and back.

Soon you'll see that tsunami is possible even in a inch-deep pool.

Where is the force coming from, the interior of mars is less dynamic than earth. Sure you can generate a hideous wave by having an imaginary cosmic foot step on mars, but like when does that happen. 

[p1t1o]

Low gravity makes large waves much easier to create for sure. Article seems to imply that it was caused by an impactor, which is entirely plausible.

[kerbiloid]

Quote

The craters that were produced were probably about 30km across, they say. The waves could have been 50m in height, or even 120m at some locations.
The areas affected by the tsunamis cover some 800,000 sq km for the older event and 1,000,000 sq km for the younger one.

Area = 800000..1000000 → Radius = 500..560 km ~= 530 km.

If use this calculator
http://impact.ese.ic.ac.uk/ImpactEffects/

and set:
Distance = 530 km
Projectile Diameter = 3 km
Projectile Density = 3000 kg/m3
Impact Velocity = 15 km/s
Impact Angle = 45 deg
Water of depth = 300 m

Final diameter of the crater = 33.7 km
Tsunami = 11...21 m.

Due to 0.35 g, on Mars this would be ~60 m. So, in narrow places up to 120 m.

Also from their book:
 

Quote

Following  some  initial  spectacular  estimates  of tsunami heights, heights that greatly exceed the depth of the ocean itself (Hills et al. 1994), a reaction occurred (Melosh 2003) based on a newly-unclassified document (Van Dorn et al. 1968) that suggests that impact-tsunami waves break on the continental shelf and pose little threat to coastal locations (the “Van Dorn” effect).

Edited May 20, 2016 by kerbiloid

[KerikBalm]

9 hours ago, PB666 said:

a world that barely had water

https://en.wikipedia.org/wiki/Mars_ocean_hypothesis

"The Mars ocean hypothesis states that nearly a third of the surface of Mars was covered by an ocean of liquid water early in the planet’s geologic history."

~33% for mars compared to 70% for earth.... yea it had smaller oceans, but still plenty of ocean for a tsunami to form.

Have you ever looked at a heightmap of mars?!

I recently made a mod planet based off of mars, adding an ocean to where the ancient shoreline of mars used to be (and other flourishes, like "life" an atmosphere with O2:

That is not "barely any water"

And thats a shoreline that has already receded from its initial levels (indeed, the shorelines seems to have been constantly receding for most of its existence)

"Features shown by the Viking orbiters in 1976, revealed two possible ancient shorelines" My guess is that these mark two periods where the water elvel was receeding slower, maybe one the initial, and a 2nd was a temporary slowdown in the water loss