One difference between mechanical and electromagnetic waves is that mechanical waves need a medium to pass through (solid, liquid, gas). EM waves can travel through matter or though a vacuum. In regards to telecommunications, EM waves can be radio waves, these are used in TV's, phones, computers, radios. Mechanical waves somewhat relate to this since radios produce sound;so an EM wave would turn into a mechanical vibration inside a speaker then sound would be produced.
Guyots are very similar to seamounts, but they have a flat surface on the top rather than a pointy one. The image shown on the question is a guyot, as it's a seamount with a flat top.
What are seamounts?
Seamounts are basically underwater mountains on the ocean floor.
Have a lovely rest of your day/night, and good luck with your assignments! ♡
