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.
1 Subduction is the process by which continental crust slides beneath another portion of crust. 2  The subducting crust melts and becomes magma, the material that fuels volcanic eruption. 3  The melted crust contains carbon in the sediments and soils, thus recycling it through the mantle of the earth. The melted crust convecting through the mantle will eventually resurface in the form of lava during eruptions from volcanoes. 2  These volcanoes were originally formed by tectonic forces--where there is an excess of magma below the crust due to subduction, it is forced to erupt. 3  The process of eruption includes degassing.