It’s all about how much silica is in the lava - not much and you have basalt, fairly runny so the gas escapes and you get fire fountaining and lava flows. More silica gives you very viscous lava like rhyolite or andesite - traps the gases, far more explosive and dangerous eruption styles.
It’s all about how much silica is in the lava - not much and you have basalt, fairly runny so the gas escapes and you get fire fountaining and lava flows. More silica gives you very viscous lava like rhyolite or andesite - traps the gases, far more explosive and dangerous eruption styles.