I would be more inclinded to look at the lunar model, where large impacts from billions of years ago filled up with lava. A large impact could cause an eruption. In the case of the Shiva crater, it landed right off the west coast of India, where the Deccan traps are located. And the Siberian traps are large enough to have covered a major impact crater, and it would be very difficult to locate an impact structure under it.
I would never think of disturbing a watermelon that is capable of self-defense.
When guns are outlawed, watermelons will have no defense against people with knives.
Asteroids are only there to "punctuate" the equilibrium.
Speaking of the effects of "Hydrostatic Shock" (or Seismic Shock in this case) One of the moons in the solar system shows the effects of an impact so large that it cratered one side of the planetoid and warped the opposing side where the shock waves interested at the mirror end of the sphere.
There is some evidence to suggest that our own moon was created in this fashion.
Massive Collision Created The Moon.
The Pacific ocean was left as the remnant of the loss of mass, Pangea (single land mass) the bulge at the opposite side of impact, Water left over from the comet that hit, and the Thermal heat of the core and subsequent volcanism a product of the transferred energy of an impact that ultimately transformed an old, cold piece of rock into a Paradise.
One might rather call that the 'Fist of God.'
I have been out of Archaeology and Geomorphology for sometime otherwise this might have been the subject of a dissertation. I would be curious to hear if anyone can expand on this theory.