Score Area: A place where each player places his scored or stolen agendas.
The score area is where a player keeps the agendas that are adding points to his/her score. Each player has his/her own score area. When the Corporation scores an agenda, s/he places it in his/her score area; when the Runner steals an agenda, s/he places it in his/her score area. Abilities on agendas are only active when in the Corporation's score area; agendas in the Runner's score area only add points to his/her score.
If the Runner has installed The Source and plays a Notoriety, does the clause "Add Notoriety to your score area as an agenda" cause The Source to be trashed?
No. Adding Notoriety to the Runner's score area is not the same as scoring or stealing an agenda, and so does not trash The Source.