Return to Tyrah's Workshop and stand on the crafting platform.
"Tyrah: Whoops! I guess the recipe isn't quite right. I'll need to revise it. Thanks for your help!"
"Tyrah: While I am figuring out the recipe for these flares, it would be helpful if you would catalog what is happening on my island..."
"Tyrah: The caves were my first attempt at terraforming... I've been hearing strange sounds coming from the southeast... can you go check them out?"
Access Quest 4: Investigate the center of the Shattered Cavern