subsidence vs settling

subsidence and settling both are nouns.

Word	Noun	Adjective	Verb	Adverb
subsidence	Yes	No	No	No
settling	Yes	No	No	No

As nouns, subsidence and settling are synonyms defined as:

Other synonyms of subsidence include subsiding.

subsidence (noun)	settling (noun)
a gradual sinking to a lower level	a gradual sinking to a lower level
the sudden collapse of something into a hollow beneath it
an abatement in intensity or degree (as in the manifestations of a disease)