You cannot adequately publicise an event without media involvement, both social and mainstream. Your industry press is likely to be particularly important in reaching your target audience.
It is worth putting some early thought into which media outlets are most likely to be interested in your event—and thinking about how to attract them. Media outlets generally want stories, so the best way to keep them interested, and get them to attend the event itself, is to feed them stories or teasers about stories that will emerge at the event. Media outlets may also agree to sponsor the event – they get their logo on communications, and you get publicity. There is more about how to do this here.
Finally, it is worth spending time building relationships with journalists and editors. Press and PR does not stop with the event, after all—especially if it was a success and you want to hold a similar event next year.