I’m in a department in which the famale faculty tend not to go out for drinks after talks. We have busy family lives, and some of us don’t drink and prefer not to socialize in bars. But this means that chat after talks can happen in bars with only male faculty and a mixed group of grad students. I don’t think this is the best atmosphere but I’m not sure how to change the culture after talks.
Some departments have found it useful to switch a format in which they take the speaker to lunch before the seminar, rather than dinner after. You might suggest this, either as a standard arrangement or as an occasional one. It could even be offered to speakers as an option. Speakers with family commitments may also be grateful for the opportunity to return home sooner.
If the bar socializing remains, it’s important to have some explicit discussion of the risks and responsibilities involved. Faculty need to be made aware that these are precisely the circumstances in which very problematic behavior often takes place, and they need to take responsibility for doing something about this– e.g. bundling a drunken visiting speaker into a taxi, intervening if they see predatory behavior starting up, etc. And students need to be aware that they shouldn’t put up with behavior that they find uncomfortable: they should either speaker up or let someone else know about the problem in time to do something about it. Bystander training may be useful for everyone.