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The Amazing Formation of Volcanic Ash: Do You Know How It's Created?
Volcanic ash is a type of tiny particles composed of rock fragments, mineral crystals and volcanic glass produced during volcanic eruptions. Its diameter is generally less than 2 mm. Although the term volcanic ash is often used more loosely, the correct name should actually be "tephra", which includes all explosive eruption products, including particles larger than 2 mm in diameter. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in molten rock are violently released into the atmosphere. This powerful gas pulverizes the molten rock and sprays it into the air, where it solidifies into volcanic ash particles.
Once volcanic ash enters the atmosphere, it is carried thousands of kilometers by wind.
The formation of volcanic ash occurs primarily in two types of eruptions: explosive eruptions and water-rich eruptions. In these eruptions, when lava reaches the surface, gases expand rapidly and form primordial bubbles, which cause lava particles to be torn apart, forming volcanic ash. When lava meets water, the instantaneous explosion of water molecules quickly turning into steam also shatters the lava blocks, further producing volcanic ash.
During the expansion process, the lava not only becomes lighter, but also erupts upward at a higher speed.
Once volcanic ash becomes airborne, it is carried by the wind and may land in distant areas. The spread of volcanic ash can lead to multiple impacts on society, including impacts on human and animal health, disruption to aviation, and damage to critical infrastructure.
Chemical and physical properties of volcanic ash
The composition of volcanic ash is closely related to the chemical makeup of the lava. Different volcanic eruption styles are directly related to their chemical composition. Generally speaking, low-energy basaltic lavas produce larger-grained ash, while high-energy rhyolite eruptions may release finer ash.
Volcanic ash may contain water, carbon dioxide, hydrogen sulfide, hydrochloric acid and other compounds that may have long-term effects on the environment and human health.
The physical properties of volcanic ash involve the shape, density and size of the particles. The shape of volcanic ash particles varies during different eruptions. The higher viscosity of rhyolite lava can cause the particles to have irregular shapes. The density of volcanic ash ranges from 700 kg/m³ to 3300 kg/m³, which makes different types of volcanic ash have different permeability in the air, thus affecting its settling behavior.
Social impacts of volcanic ash
With the development of human society, more and more cities are being built closer to volcanic areas. Such conditions increase the risk of urban residents being affected by volcanic ash. Volcanic ash emissions often have devastating effects on urban infrastructure, especially when there is a lack of preparation.
The consequences of volcanic ash are not limited to short-term impacts; they can also cause long-term health problems as well as social and economic losses.
While the effects of volcanic ash exposure in generally healthy people are brief and mild, those with pre-existing respiratory conditions are at greater risk. In particular, tiny particles of volcanic ash suspended in the air may cause respiratory discomfort, eye and skin irritation, etc. The increasing health risks and confirmed cases caused by volcanic ash emissions have forced people to rethink the impact of volcanic ash and its prevention measures.
Have you ever wondered how the formation process of volcanic ash can once again affect our lives and the environment?
