<Li> Pinatubo in the Philippines on 15 June 1991, which produced 5 km (1 cu mi) of dacitic magma, a 40 km (25 mi) high eruption column, and released 17 megatons of sulfur dioxide . </Li> <P> Phreatomagmatic eruptions are eruptions that arise from interactions between water and magma . They are driven from thermal contraction (as opposed to magmatic eruptions, which are driven by thermal expansion) of magma when it comes in contact with water . This temperature difference between the two causes violent water - lava interactions that make up the eruption . The products of phreatomagmatic eruptions are believed to be more regular in shape and finer grained than the products of magmatic eruptions because of the differences in eruptive mechanisms . </P> <P> There is debate about the exact nature of phreatomagmatic eruptions, and some scientists believe that fuel - coolant reactions may be more critical to the explosive nature than thermal contraction . Fuel coolant reactions may fragment the volcanic material by propagating stress waves, widening cracks and increasing surface area that ultimately leads to rapid cooling and explosive contraction - driven eruptions . </P> <P> A Surtseyan eruption (or hydrovolcanic) is a type of volcanic eruption caused by shallow - water interactions between water and lava, named so after its most famous example, the eruption and formation of the island of Surtsey off the coast of Iceland in 1963 . Surtseyan eruptions are the "wet" equivalent of ground - based Strombolian eruptions, but because of where they are taking place they are much more explosive . This is because as water is heated by lava, it flashes in steam and expands violently, fragmenting the magma it is in contact with into fine - grained ash . Surtseyan eruptions are the hallmark of shallow - water volcanic oceanic islands, however they are not specifically confined to them . Surtseyan eruptions can happen on land as well, and are caused by rising magma that comes into contact with an aquifer (water - bearing rock formation) at shallow levels under the volcano . The products of Surtseyan eruptions are generally oxidized palagonite basalts (though andesitic eruptions do occur, albeit rarely), and like Strombolian eruptions Surtseyan eruptions are generally continuous or otherwise rhythmic . </P>

Three types of volcanoes on the basis of periodicity of eruption