The police are now monitoring criminal/gang/drug 'activity' in the area.
There has been an increase in the city's (level of) economic 'activity'.
The instruments are used to detect volcanic 'activity' on the island.
(..) my dear Pepi, you double-cross me, it'll be a very long while before you give your next piano recital. Yes? You asked me to keep you informed of Lady Litton's activities. Yes. Well, she's going skiing at . Skiing in this weather? On the glacier. On the glacier? Psst. (..)1975 The Return of the Pink Panther