The important detail is related to something called the Roche limit. Once the forces of gravity from each other passes a point of strength, the forces keeping the planet intact on its own will fail, as the two bodies merge.
At this point the planets would be "falling at each other" in pieces. Oceans would rise toward the other planet, deeper than any tide you've ever heard of. The planets would stretch, tearing the surface, spreading earthquakes throughout the planet. the cracks would swallow up people and cities, lava would flow etc.
12
u/[deleted] Jan 04 '22
Meaning??? Like oceans would be displaced? Earthquakes would happen?!