# Impact craters under water

What would be the resulting impact crater of a meteorite hitting bodies of water on Earth?

Let's take for example the impactor that resulted in Meteor Crater, Arizona. What would the impact look like if it hit a shallow sea? A deep ocean? Is there any depth of water which would result in no crater at all?

• A cool question. Would be nice to have formulae for crater's true & apparent radius & depth, ejecta volume as functions of meteorite size, impact velocity and angle, depth, & type of seabed. Also interesting whether water density makes a difference. Oct 18, 2015 at 13:19
• For want of a better term, the "cohesion/fusion" of a meteor & what it's made of would be important. A massive chrondrite meteor would create a crater on land but might fall apart as it travelled through deep water whereas as a dense iron-nickel meteor would have a deeper penetration capability in water & maintain more of its kinetic energy as it moved through water.
– Fred
Oct 18, 2015 at 13:23
• Oct 18, 2015 at 22:11
• @Fred actually the strength of the meteorite material has no effect at all. It is totally about the kinetic energy of the object. The event, whether marine or terrestrial, is essentially identical to an explosion of the same energy as the original kinetic energy, centered sightly beneath the surface. Oct 19, 2015 at 1:57
• @stali fascinating article. Full version PDF here: onlinelibrary.wiley.com/doi/10.1029/2009RG000308/epdf I read the conclusion and I was shocked that an important parameter was ignored, namely velocity of the object relative to Earth, which can vary by a factor of 7, therefore the kinetic energy can vary by a factor of 50 for the same object mass! Which completely overwhelms any consideration of object density, which they did address. The initial water cavity is a fairly straightforward exercise, but what happens after, both in the fluid & the seafloor, is incredibly complicated. Oct 19, 2015 at 2:08

You don't need much of a depth to be able to stop a meteorite. Less than 100 m water depth should be enough to stop such a meteorite as shown in the provided link without any particular crater on the sea bed.

The rest is mathematics.

Short. At collision all the kinetic energy is transferred to Pressure, and thereafter this pressure is again transferred to kinetic energy; it is explosion. Very simply said it's Bernoulli principle.

By this reason it doesn't penetrate practically any deeper in water than in Earth, and as the water then smooths up you have no crater. A very simple scaling might be made with density; typical rock / water; 2.3/1 depth.

If you need some visual proof, try this video;