volcanology vs geophysics

volcanology and geophysics both are nouns.

Word	Noun	Adjective	Verb	Adverb
volcanology	Yes	No	No	No
geophysics	Yes	No	No	No

As nouns, geophysics is a hypernym of volcanology; that is, geophysics is a word with a broader meaning than volcanology:

volcanology: the branch of geology that studies volcanoes
geophysics: geology that uses physical principles to study properties of the earth

Other hypernyms of volcanology include geophysical science.

volcanology (noun)	geophysics (noun)
the branch of geology that studies volcanoes	geology that uses physical principles to study properties of the earth