Phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a very fine grained matrix. Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava.
A Vulcanian eruption is a short, violent, relatively small explosion of viscous magma (usually andesite, dacite, or rhyolite). This type of eruption results from the fragmentation and explosion of a plug of lava in a volcanic conduit, or from the rupture of a lava dome (viscous lava that piles up over a vent).ere are some of the most common types of eruptions: In a Hawaiian eruption, fluid basaltic lava is thrown into the air in jets from a vent or line of vents (a fissure) at the summit or on the flank of a volcano.
Number of deaths due to the world's major volcanic eruptions from 1900 to 2015*. The statistic presents the death toll in individual countries due to the world's major volcanic eruptions from 1900 to 2015*. The volcanic eruption in Cameroon on August 24, 1986 claimed a total of 1,746 deaths.Volcanic eruptions.A volcanic eruption is defined as a discharge of lava and gas from a volcanic vent or fissure. Volcanoes spew hot, dangerous gases, ash, lava, and rock that are powerfully destructive.he volcanic eruption in Cameroon on August 24, 1986 claimed a total of 1,746 deaths. Volcanic eruptions. A volcanic eruption is defined as a discharge of lava and gas from a volcanic vent or fissure. Volcanoes spew hot, dangerous gases, ash, lava, and rock that are powerfully destructive.