Full Idea
A state of affairs consists of structures of particulars that endure (of which physical objects would be one type), the properties and powers of those particulars, and the relations obtaining among them. A common 'event' is a change in state of affairs.
Gist of Idea
Events are changes in states of affairs (which consist of structured particulars, with powers and relations)
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 6.IV)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.109
A Reaction
I find 'event' to be so vague, and so dependent on pragmatic interests, that it has hard to find a place for it in an ontological system. Ditto with state of affairs. They overlap. States of affairs can survive change (like a political majority).