**11. Explosive eruptions of the hydromagmatic type that produce fall-out bedded deposits Vulcanian eruption**

Vulcanian eruptions are direct explosive eruptions rich in magmatic volatile or any water [38].

Phase 1: The magma rich in volatiles interacts with the groundwater causing rapid vaporization and the relative production of water vapor that increases the explosiveness of the eruption.

#### **Figure 30.** *Volcanian eruption (author's collection).*

**Figure 31.** *Scoria deposit caused by a Volcanian eruptions (modified from Schmincke [14]).*

Phase 2: The expulsion of the products is characterized through a number of discrete explosions that follow one another in variable intervals between 10 min and 1 h comparable to cannon shots.

The single explosions produce eruptive columns between 5 and 10 km high (**Figure 30**). A typical example of scoria Vulcanian products is shown in **Figure 31**.

**Figure 32.**

*(a): Phreatoplinian eruption; and (b): Surtseyan eruption (modified from Schmincke [14]).*

**Figure 33.** *Pyroclastic flow (modified from Branney and Kokelaar [31]).*
