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Volcanic lava: How does it erupt from the interior of the Earth?
Lava is molten or partially molten rock (i.e. magma) that erupts from the Earth's interior, usually from the Earth's crust at very high temperatures. Lava can be ejected in volcanic eruptions or through cracks in the Earth's crust, either on land or underwater, and its temperature is typically between 800 and 1200 °C (1470 and 2190 °F). The volcanic rock that forms as it cools is often called lava. Lava flows are the outflow of molten rock during an effusive eruption, in contrast to explosive eruptions which produce a mixture of ash and other debris, called tephra, rather than lava flows.
Lava is about as viscous as ketchup and about 10,000 to 100,000 times more viscous than water.
Lava can flow long distances until it cools and solidifies because lava exposed to air often quickly forms a hard crust that insulates the remaining liquid lava and helps keep it hot and fluid. The properties and behavior of lava are influenced by many factors, including its chemical composition, temperature, and viscosity.
Composition and properties of lava
Solidified lava on the Earth's crust is mainly composed of silicate minerals, including feldspar, silicates, olivine, and garnet. In particular, silicate lavas are composed of two elements, oxygen and silicon, which dominate the molten mixture. In Earth's crust, the way silicon and oxygen combine affects the physical behavior of molten rock.
The viscosity of lava largely determines its flow behavior; the greater the viscosity, the more explosive an eruption tends to be.
Different Types of Lava
Lava can be divided into four chemical types, depending on the silica content: felsic, intermediate, mafic, and ultramafic. in,
- Silicate lava: contains more than 63% silica and usually erupts explosively, forming volcanic ash.
- Neutral lava: contains 52% to 63% silicon and is common in composite volcanoes such as the Andes.
- Basic lava: Lava with high magnesium oxide and iron oxide content, usually forming low shield volcanoes.
- Ultrabasic lava: contains less than 45% silica and can form very fluid lava.
The flow and cooling of lava
There is a direct relationship between the flow rate of lava and its viscosity. Typically, lava is most fluid right after an eruption, but becomes more viscous as the temperature drops. As the lava cools, it shrinks and can cause the lava flow to break up, which affects its surface structure and creates unique natural textures. Therefore, the shape and appearance of lava flows are very diverse.
The shapes of lava flows include flat lava flows, brick-like lava, and special structures of underwater lava, which affect the formation of landforms.
Culture and etymology of lava
The word "lava" is of Italian origin, presumably derived from the Latin "labes," meaning "slide" or "slope." An early use of the word was associated with the eruption of Mount Vesuvius in 1737, when the flowing lava was likened to a stream of water, picking up mud and moving downward.
The Future of Lava and Scientific Exploration
While we have a better understanding of the properties and dynamics of lava, there are still many unanswered questions about its interaction with life and the environment on Earth. Scientists continue to study how lava shapes Earth's landscape and its potential impact on climate change. In this context, understanding the nature of lava is not only a key to understanding physical geography, but also a key to interpreting the past, present and future of our planet.
As technology advances and the study of lava deepens, can we uncover more about the mysteries of these mysterious liquids?
