isoseismal vs isarithm

isoseismal and isarithm both are nouns.

Word	Noun	Adjective	Verb	Adverb
isoseismal	Yes	No	No	No
isarithm	Yes	No	No	No

As nouns, isarithm is a hypernym of isoseismal; that is, isarithm is a word with a broader meaning than isoseismal:

isoseismal: a line on a map connecting points at which earthquake shocks are of equal intensity.
isarithm: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isoseismal include isogram, isopleth.

isoseismal (noun)	isarithm (noun)
a line on a map connecting points at which earthquake shocks are of equal intensity.	a line drawn on a map connecting points having the same numerical value of some variable