Halloween Zombie Hordes

Released as part of halloween events. As the name suggests this event happens just before halloween, when zombies start clawing their way out of the ground of Gielinor. They come in waves, sometimes bringing skeletal hands with them on the second.

Locations
This can happen in any world- member's or free to play- but generally occurs in one of the following locations
 * 1) lumbridge
 * 2) al kharid (mines or town)
 * 3) draynor
 * 4) the grand exchange
 * 5) edgeville
 * 6) varrock square
 * 7) falador castle
 * 8) clan wars portals
 * 9) daemonheim

Clues as to location and world are released soon before an attack by a j-mod on the official forum thread. You can also follow the attacks by joining the friends chat channel "UndeadTracks" in game, where scouts and zombie hunters exchange information organize themselves.

Update
The official announcement came on October 14th, 2011 in an update callled "the dead walk" posted by mod crow and mod kathy. Part of the article hinted that the hordes would increase in strength as they got father into the month-

"These strikes can happen anywhere, on any world and at any time. The sages augur that as we approach All Hallows Eve we will see the power of the unquiet dead grow, from the crawling hands seen recently, to shambling, dangerous zombies in the weeks leading up to Halloween. The scrying pools grow dark and our seers dare not delve into events surrounding Halloween itself; all we know is that whatever manifests will be truly terrible."

Trivia
-although the post stated that the hands would come through to gielinor first, they seem to appear on the second wave most times.

-it is also worth noting that these zombies are different than the usual attackable npc- they have hair, and although they are level 26 at the moment they are not agressive to lower levels.

-often between waves players will use their living on borrowed time emote from deathcon II to keep the mood going.

-despite rumors there are no rewards other than fun andthe bones dropped for killing the hordes