Sometimes erupts violently forming a layer of tephara sometimes a quieter eruption forming a lava layer?

Volcanic activity can vary significantly, resulting in different types of eruptions. A violent eruption typically produces tephra, which includes ash, pumice, and other volcanic debris, creating layers of fragmented material. In contrast, a quieter eruption may result in the effusion of lava, leading to the formation of solidified lava layers. The nature of the eruption depends on factors like magma composition, gas content, and pressure build-up within the volcano.