Lava Lakes are form in craters or depressions and are when molten lava is ponded. Basalt is the most common type of lava lake as it is highly fluid. The surface of the lake is cooled by the atmosphere and can appear solid but is only cm s thick. The surface mimics the processesof plate tectonics as convection currents below cause turbulence which moves the cracked crust around.Mini subduction and spreading occurs giving an insight into the larger forces at work with tectonic plates.
Nyiragongo , a stratovolcano in Nigeria contains the worlds largest lava lake. Its lava has a very low viscosoity and when it overtops the crater can flow at 60mph helped by the steep slopes of the volcano. Kilauea on Hawaii also has two lava lakes ,one within the summit crater and one from the vent Pu u oo.