Volcanic Fissure - Aftershock clarification

The Volcanic Fissure skill text reads:

"

Slam the ground, creating a winding fissure that deals damage as it travels and remains for a duration. Using a different Slam on a fissure will cause an Aftershock, which spreads to all connected fissures.

My question concerns the Aftershock portion of the skill: Is the aftershock damage based A. on the Volcanic Fissure damage or B. the damage of the different slam skill?

B seems unreasonable if you could place 5 fissures then use one hammer of the gods to proc a dozen hammer of the gods tier aftershocks

the other thing im curious about, is it says "aftershock" which is an aoe effect thing, but if you test out volcanic fissure it doesn't seem like there are any aftershocks at all
it seems like there is just this reverb through the fissures and thats it