What is volcanic ash (volcanic ash), and why is it dangerous?

Following the closure of European airports for the second time in a year due to the eruption of a volcano in Iceland, we bring again the scientific explanation of the risk posed by the volcanic ash to airplanes and other factors

Volcanic ash consists of tiny, jagged particles of natural glassy rock thrown into the air by a volcanic eruption. The ash can threaten the health of people and animals, is a danger to passenger planes, may cause damage to electronic systems and machines and interfere with electricity production and communications. The wind can carry the ash for many kilometers, affecting more distant areas and many more people than the direct damages of the eruptions. Even after the emission of ash from the volcano ends, the wind and human activity can cause the ash to fall for months and even years and cause long-term health and economic damages.

The case of St. Helens as an example

On the morning of May 18, 1980, many residents of eastern Washington State noticed that it was getting dark and threatening clouds were coming from the west. Most believed that the clouds were part of a system of large thunderstorms common in late spring. However, what they didn't know was that at 08:32 the St. Helens volcano erupted and shot a huge jet of gas and volcanic ash over 20,000 meters into the air.

As the cloud swept over them, a shower of ash began to fall, covering the area in darkness for the rest of the day. Houses, farms and roads were quickly covered in 10 centimeters of dust. The small particles penetrated the machines and all the structures except for the particularly sealed ones. By the end of the day over 500 million tons of ash had fallen over parts of Washington, Idaho and Montana. The ash prevented the possibility of road travel in eastern Washington state due to poor visibility, slippery roads and the impact of the dust on cars, an impact that was felt by about ten thousand people in isolated areas and small communities. Calcutta suffered a loss of over a billion dollars due to the eruption of the St. Helens volcano in 1980 - most of it due to the ash. If a volcanic eruption were to occur in the USA today, the damage would be much greater due to the increase in population and economic activity since the XNUMXs in the western USA. Much more widespread use of computers and electronics and a sharp increase in the amount of flights, especially over the North Atlantic Ocean, have made more people and more property vulnerable to the impact of volcanic ash. Knowing the characteristics of volcanic ash and being prepared for it when the volcano shows signs of restlessness can reduce the economic damage and health consequences of the ash.

What is volcanic ash?

Jagged particles of rocks, minerals, and volcanic glass made of sand and silt 2 millimeters or less in diameter that are ejected from volcanoes are called volcanic ash. The smallest of these particles can be 0.001 millimeters wide). Unlike the shavings created from cutting wood, leaves or paper, the volcanic ash is hard, does not dissolve in water, is jagged and causes erosion, and it also serves as a good electrical conductor when wet.

Volcanic eruptions occur when gases are absorbed by molten rock (magma) and together they escape from the volcano into the air, when it is a wet area, the water also adds to the celebration and turns into steam. The escaping forces cause the rocks to tear, and the lava erupts into the air where it hardens and crystallizes into particles of volcanic rocks and glass. The intensity of the eruption is such that the ash and gas particles create a huge eruption column, sometimes over 10 kilometers high. Fragments and rocks larger than 5 centimeters are ejected and fall in the immediate vicinity, at a distance of a few kilometers from the site of the eruption, but the finer particles are carried by the wind in a visible form as an eruption cloud. As the cloud moves with the wind from the volcano, the heavier ash falls and the cloud is made up of thinner ash layers. The ash cloud can travel thousands of kilometers and even circle the earth.

Some consequences of the volcanic ash

When the volcanic ash accumulates on buildings its weight can cause the roofs to collapse, killing or injuring their occupants. A dry layer of ash 10 centimeters thick can weigh up to 100 kilos per square meter, and wet ash can weigh as much as double. The intensity of the damage depends on the shape of the roof - flat roofs tend to collapse faster than sloped roofs.

Because the ash is electrically conductive, it can short circuits and disable electronic components, especially high voltage circuits and transformers. Power outages are common in areas affected by the ash, and therefore it is recommended to install electrical backup systems in sensitive facilities such as hospitals.

It turns out that even the media - including the cellular one - may suffer damage - when the ash affects in several ways - starting with shorting out end equipment and transmission antennas, the lightning created as a result of electrical voltage discharge also damages and the radio waves are scattered or swallowed by the hot and charged particles.

Damage to car and aircraft engines

Volcanic ash can cause internal combustion engines to break down due to the clogging of air filters leading to damage to moving parts of vehicle engines and machines, including the relays and gears. Jet engines may stop working after flying through the cloud containing even thin ash. Roads, highways and airport runways can become dangerous and unusable due to their slickness and near-zero visibility. Driving a car at a speed of over 8 km/h on roads in an area covered in ash means a real danger of a car accident.

The ash can also clog cooling air conditioning filters for computers based on air flow, which will cause the computers to heat up. Agriculture may also be affected by the fall of volcanic ash, the damage to grain varies according to the thickness of the ash layer, the type of plants and their age, and the timing of the rain that follows. Farm animals, especially grass-fed animals, may suffer health damage, including dehydration, starvation and poisoning.

Like any flow of particles from other sources such as wind bringing dust from the desert (as happened to us last week), forest fires and air pollution, the volcanic ash may cause health problems especially for children, the elderly and people suffering from heart disease or respiratory diseases such as asthma, chronic bronchitis and emphysema ( emphysema). Therefore it is recommended to listen to forecasters who convey this information to the public. The science of meteorology makes it possible to get a forecast hours and even days before the arrival of the cloud and thus the victims can minimize the damages. The US Geological Survey constantly monitors over 40 active volcanoes in the US.