Question

How can I activate the Goroma's Volcano world change?

Answer 1

You can't activate this world change. This mini world happens at least once a month, I think. You must check the notice board in the Adventurer Guild. 

Answer 2

You can't activate it. You have to wait for world event. You can check it by using the world board near Npc Charos .

You will see text:

World Board: The volcano on Goroma sends his fiery message into the sky. A lot of creatures are flooding the lands together with its lava.

or from Npc near Thais boat:

Towncryer: Hear ye! Hear ye! The volcano on Goroma is spitting fire. Creatures are spawning, strong and dire. Lava is heading up the land. Adventurer, be careful or it will be your last stand!

Comments

good that you added it. not everyone knows where the board is : d

Answer 3

I guess this is a random change...

You are able to know if it's activated in Adventurer's Guild (using Adventurer Stone inside the temple), using the World Board.

It calls Fire From Earth World Change.

NPC Towncryer: Hear ye! Hear ye! The volcano on Goroma is spitting fire. Creatures are spawning, strong and dire. Lava is heading up the land. Adventurer, be careful or it will be your last stand!

World Board: The volcano on Goroma sends his fiery message into the sky. A lot of creatures are flooding the lands together with its lava.

Answer 4

You can not active this event.  Its a random evend. You need to check what npc in thais says :
Towncryer: Hear ye! Hear ye! The volcano on Goroma is spitting fire. Creatures are spawning, strong and dire. Lava is heading up the land. Adventurer, be careful or it will be your last stand!

Or check  World Board:The volcano on Goroma sends his fiery message into the sky. A lot of creatures are flooding the lands together with its lava.