shore vs shore up

shore is a noun but shore up is not a noun.

Word	Noun	Adjective	Verb	Adverb
shore	Yes	No	Yes	No
shore up	No	No	Yes	No

As verbs, shore and shore up are synonyms defined as:

Other synonyms of shore include prop, prop up.

shore (noun)	shore up (noun)
a beam or timber that is propped against a structure to provide support
the land along the edge of a body of water

shore (verb)	shore up (verb)
support by placing against something solid or rigid	support by placing against something solid or rigid
arrive on shore
serve as a shore to