Brand New = 0 merit airdrop
Newbie = 0 merit aidrop
Junior Member = 0 merit airdrop
Member = 10 merit airdrop
Full Member = 100 merit airdrop
Senior Member = 250 merit airdrop
Hero Member = 500 merit airdrop
Legendary = 1000 merit airdrop
Initially, Hero member got 500 merit, Legendary get 1000 merit, not smerits. Smerit is calculated with the formula.
Later Hero member with >=775 activity got 500 more merit.
The exact formula was:
yearActivity = activity in the last ~year, max 378
freeMerit = the merit (not sMerit) you started with
modifier =
0.1 if member
0.2 if full member
0.25 if sr member
0.35 if hero
0.4 if legendary
return (yearActivity/378) * modifier * freeMerit
So the most you could get is if you were a Legendary who maxed out your activity points in the last year, in which case you would get 1 * 0.4 * 1000 = 400 sMerit.
Note that I later made an adjustment giving 500 extra merit to some hero members, but no extra sMerit was given here.
I'll probably publish a dump of the initial sMerit at some point.
I decided that the previous allocation was too unfair in this area, so everyone with activity >= 775 got 500 more merit if they didn't already have 1000 merit (and also Lutpin). No extra sMerit, though.