A new campaign was undertaken by Justinian's nephew Germanus Justinus, but he died in 551 CE, succeeded by the general Narses. In 553 CE, Narses defeated Totila and Italy was once again Roman. Justinian's reign lasted almost 40 years, but it was not always popular.
Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent.ome of this magma may cool extremely rapidly and will form volcanic glass (rocks without crystals) such as obsidian. Magma that remains trapped below ground in thin intrusions cools slower than magma exposed to the surface and produces rocks with medium-sized crystals.
A volcanic eruption is the release of molten rock and volcanic gases through Earth 's crust to the surface. Molten rock within the earth, or magma, is driven to erupt by buoyancy because it is lighter than the surrounding rock. Dissolved gases within the magma are under great pressure and force magma upwards.olcanoes are vents or fissures in Earth 's crust through which lava, gases, and pyroclastic debris are released. More commonly, the term volcano refers to the landform built up from the accumulation of lava and/or pyroclastic debris.