Both in the Lost World book and movie, it's implied InGen(?) bought and/or scared the survivors from talking about the incident.
The Lost World movie sort of mocks this idea by creating an incident they couldn't hide, which is then confirmed by the third one, when every journalist wants to ask Grant about it in a conference.
That's why I wonder which version of Ian Malcom is going to appear in JW2. The one who's been silent for years about the dangers of these animals while watching them build and open a new park on TV, or the one who outran a T-Rex with a convertible in San Diego.