Lava is one of the most fascinating and awe-inspiring natural phenomena on Earth. But what is lava exactly, and how does it form? In this article, we will explore the science behind lava, its different types and characteristics, and why it can reach such high temperatures.
What is Lava?
Lava is the term used to describe molten rock that erupts from volcanoes or fissures on the Earth’s surface. Lava is formed when rocks in the Earth’s mantle or crust melt due to high pressure and temperature. The melted rock, called magma, rises through cracks or vents in the Earth’s crust and reaches the surface, where it cools and solidifies into igneous rock.
Types of Lava
Not all lava is the same. Depending on the chemical composition, temperature, and viscosity of the magma, lava can have different properties and behaviors. Some of the main types of lava are:
Pahoehoe lava: This type of lava has a smooth, ropy, or wrinkled surface. It is very fluid and can flow fast and far. Pahoehoe lava is usually basaltic, meaning it has a low silica content and a high iron and magnesium content. Pahoehoe lava is common in Hawaii and Iceland.
Aa lava: This type of lava has a rough, jagged, or blocky surface. It is more viscous and less fluid than pahoehoe lava, and tends to move slower and form thicker flows. Aa lava is also usually basaltic, but it has more gas bubbles and crystals than pahoehoe lava. Aa lava is also common in Hawaii and Iceland.
Pillow lava: This type of lava forms when lava erupts underwater or near the coast. It has a rounded, pillow-like shape with a thin crust. Pillow lava is also basaltic, but it cools very quickly when it comes in contact with water. Pillow lava is found in oceanic ridges and islands.
Andesitic lava: This type of lava has a higher silica content than basaltic lava, which makes it more viscous and less fluid. It also has a lower temperature and a lighter color than basaltic lava. Andesitic lava tends to form thick, dome-shaped flows or explosive eruptions. Andesitic lava is common in the Andes mountains and other subduction zones.
Rhyolitic lava: This type of lava has the highest silica content of all lavas, which makes it very viscous and almost solid. It also has a very high temperature and a light color. Rhyolitic lava tends to form explosive eruptions or thick, glassy flows. Rhyolitic lava is common in continental volcanic areas such as Yellowstone.
Why is Lava So Hot?
Lava can reach temperatures ranging from 700Â°C to 1200Â°C (1300Â°F to 2200Â°F), depending on the type of magma and the depth of its origin. The main source of heat for magma is the radioactive decay of elements such as uranium, thorium, and potassium in the Earth’s interior. This heat causes the rocks to melt and form magma.
Another source of heat for magma is the friction caused by the movement of tectonic plates. When plates collide or diverge, they create cracks or subduction zones where magma can rise to the surface. The friction between the plates and the magma also generates heat.
A third source of heat for magma is the pressure exerted by the overlying rocks. As magma rises to the surface, it encounters less pressure and expands. This expansion lowers the melting point of the magma and makes it hotter.
Lava is a fascinating natural phenomenon that results from the melting of rocks in the Earth’s interior. Lava can have different types, characteristics, and behaviors depending on its chemical composition, temperature, viscosity, and eruption style. Lava can also reach very high temperatures due to various sources of heat such as radioactive decay, friction, and pressure.