How do Jupiter's moon Io's volcanoes erupt so intensely?

Io is the most volcanically active body in the Solar System because it is squeezed and stretched by Jupiter’s gravity. The neighboring moons Europa and Ganymede keep Io in a slightly elongated orbit, so tidal forces change continuously as it moves around Jupiter. That flexing creates internal friction, which heats Io’s interior and melts rock into magma. NASA’s Voyager missions first showed Io’s erupting plumes in 1979, and later missions confirmed ongoing volcanic activity. Unlike Earth’s volcanoes, Io’s eruptions are driven mostly by gravity rather than plate tectonics.