explosion-dominated eruptions occur when a body of magma (called a "dike") from deep within io's partially molten mantle reaches the surface at a fissure. this results in a spectacular display of lava fountains. during the beginning of the outburst eruption, thermal emission is dominated by strong, 1–3 μm infrared radiation. it is produced by a large amount of exposed, fresh lava within the fountains at the eruption source vent. outburst eruptions at tvashtar in november 1999 and february 2007 centred on a long, tall lava "curtain" produced at a small patera nested within the larger tvashtar paterae complex.