Wizard island is a new volcanic cone growing out of the lake. These volcanic chains exist because subduction is occurring along most of the rim of the Pacific. Hawaii Volcanoes - Big island of Hawaii is the active volcano of a hot spot. The other islands, to northwest, are extinct volcanoes that have moved off the hot spot. Formed by thousands of successive layers of basalt flows.
Basaltic lava has relatively low viscosity, so flows move far and fast.