Pu'u O'o was angrier than last year. What you are looking at is the vog coming out of the vent about a mile or so off and coming right at you. You are not supposed to go past this point to get any closer.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .