seism vs microseism

seism and microseism both are nouns.

Word	Noun	Adjective	Verb	Adverb
seism	Yes	No	No	No
microseism	Yes	No	No	No

As nouns, microseism is a hyponym of seism; that is, microseism is a word with a more specific, narrower meaning than seism:

seism: shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity
microseism: a small earthquake

Other hyponyms of seism include seismic disturbance, shock, earth tremor, tremor, seaquake, submarine earthquake.

seism (noun)	microseism (noun)
shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity	a small earthquake