1.)what do you understand by volcano?
2.)What is volcanic eruption?
answer In para. according to 5 Marks.
Answers
Answer:
1) volcano is an opening in the earth’s crust through which lava, volcanic ash, and gases escape. Volcanic eruptions are partly driven by pressure from dissolved gas, much as escaping gases force the cork out of a bottle of champagne. Beneath a volcano, liquid magma containing dissolved gases rises through cracks in the Earth’s crust. As the magma rises, pressure decreases, allowing the gases to form bubbles. How the magma (lava) behaves when it reaches the surface depends on both its gas content and chemical composition. Lavas with low silica contents have low viscosities and flow freely, allowing any gas bubbles to escape readily, while lavas with high silica contents are more viscous (resistant to flow), so that any trapped gases cannot escape gradually.
2) Volcanic eruption-cyclicity is the whole of erupted materials, inside volcanic structures, which are generated during one volcanic activity period, and is generally formed through the erupted volcanic rocks overlaid from several edifices and sedimentary rocks between different volcanic edifices.
The volcanic eruption-cyclicity framework is under magma-migration joint control, evacuation, and filling in of magma chambers, reflecting the entire volcanic activities process from starting time to peak time, then into recession time and dormant time. The thickness variation and framework spatial geometrical shapes, are related to the volcanic eruption mode and the eruption center position. The thickness of the high-value zone shows that the eruption center is near and the eruption has large-scale characteristics, high frequency, long-lasting time, and an abundant supplement of eruptive materials. The low-value zone shows a long distance far from the eruption center, the eruptive materials supplement is relatively poor, the rock thickness is low, and is in depression area between volcanic edifices. Framework shapes represent volcanic eruption modes and volcanic rock spatial distribution patterns. Generally, under the fracture-eruption type, the formed volcanic stratum is layer-spread along fault belts, and its spatial distribution is stable with little strata thickness variation; but under the central-eruption type, the formed volcanic stratum is independent or is bead-spread along fault belts, which shows cone shape apparent features, moundy shape and the strata thickness varies greatly.
In south and west China, the volcanic eruption-cyclicity framework scales are different for different eruption modes, energy, and environment. Generally speaking, the plane areal extent can reach tens to hundreds of kilometers and the vertical depth can reach hundreds to thousands of kilometers. The volcanic eruption-cyclicity framework apparently controls the spatial spread and reservoir strata-thickness variation. In gas reservoir development, the volcanic eruption-cyclicity frameworks are employed to research into volcanic eruption modes and rock distribution patterns.
Answer:
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater.
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