I think blogs should have an indicator for possible triggers. This is my proposal:
When we're composing blogs, there should be an option (maybe under the "Allow Comments" option) we can select that reads "Trigger Warning". If this option is clicked, a textbox will appear under it where you can type in possible triggers. An alternative option is a drop down menu where you can select from a list of possible triggers (but I think manually typing it in is a better method). Listing each one, separated by commas, would be good.
Then blogs with a trigger warning should be indicated by a red dot at the corner of the rating icon thingie, or maybe next to it. When you open the blog, the triggers should be in collapsible box at the top.
Although the intent is very good, I feel like we can leverage our current system to do this.
First of all, you could put, in some sort of alerting manner, a preface on the top of your blog to alert people of possible triggers. You could even put [TRIGGER WARNING] in your title. You could request the blogmins to add an M rating.
An issue arises whenever this system is in place, yet the author could not be bothered to add it in. The expectation would be that there would be no triggers, but there indeed would be, so there would be some sort of disconnect between what is promised and what is delivered.
Honestly, I think this idea could definitely be implemented if the core idea is honed a little.