seaquake vs earthquake

seaquake and earthquake both are nouns.

Word	Noun	Adjective	Verb	Adverb
seaquake	Yes	No	No	No
earthquake	Yes	No	No	No

As nouns, earthquake is a hypernym of seaquake; that is, earthquake is a word with a broader meaning than seaquake:

seaquake: an earthquake at the sea bed
earthquake: shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity

Other hypernyms of seaquake include quake, seism, temblor.

seaquake (noun)	earthquake (noun)
an earthquake at the sea bed	shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity
	a disturbance that is extremely disruptive