If the edge of a tectonic plate suddenly flicks upward under the ocean, it can displace a large amount of water, which may form a tsunami at the surface of the ocean. This typically occurs at convergent plate boundaries where one oceanic plate subducts beneath another, causing sudden vertical movements of the seafloor that displace water and generate powerful tsunami waves

. In summary:

• Sudden upward flicking of a plate edge displaces water.
• This displacement can create a tsunami on the ocean surface.
• Tsunamis are common in convergent oceanic-oceanic plate boundaries due to strong earthquakes and vertical seafloor shifts