which type of volcano has explosive eruptions due to thick magma
Types of volcanic eruptions Vulcanian eruptions are a type of volcanic eruption, named after the volcano Vulcano.[20] It was named so following Giuseppe Mercalli's observations of its 1888–1890 eruptions.[21] In Vulcanian eruptions, intermediate viscous magma within the volcano make it difficult for vesiculate gases to escape. Similar to Strombolian eruptions, this leads to the buildup of high gas pressure, eventually popping the cap holding the magma down and resulting in an explosive eruption. However, unlike Strombolian eruptions, ejected lava fragments are not aerodynamic; this is due to the higher viscosity of Vulcanian magma and the greater incorporation of crystalline material broken off from the former cap. They are also more explosive than their Strombolian counterparts, with eruptive columns often reaching between 5 and 10 km (3 and 6 mi) high. Lastly, Vulcanian deposits are andesitic to dacitic rather than basaltic.[20]
Hawaii hotspot Wilson proposed that mantle convection produces small, hot buoyant upwellings under the Earth's surface; these thermally active mantle plumes supply magma which in turn sustains long-lasting volcanic activity. This "mid-plate" volcanism builds peaks that rise from relatively featureless sea floor, initially as seamounts and later as fully-fledged volcanic islands. The local tectonic plate (in the case of the Hawaii hotspot, the Pacific Plate) slowly slides over the hotspot, carrying its volcanoes with it without affecting the plume. Over hundreds of thousands of years, the magma supply for the volcano is slowly cut off, eventually going extinct. No longer active enough to overpower erosion, the volcano slowly sinks beneath the waves, becoming a seamount once again. As the cycle continues, a new volcanic center manifests, and a volcanic island arises anew. The process continues until the mantle plume itself collapses.[1]