How dangerous are volcanoes?

Lava at around 1000 degrees, explosions, burning streams – volcanoes are dangerous, no question about it.
Fortunately, it is now possible to predict where an eruption is likely to occur, and when it is imminent, a clear volcanic tremor warns people in the surrounding area. With modern science, this means that it is usually possible to evacuate in time and people die less and less often from volcanic eruptions.
Nevertheless, they are beasts. They are fire-breathing dragons that simply roll over houses and fields as if nothing were there. They have a destructive power that we humans cannot fight. We can only deal with the dangers emanating from volcanoes and avoid personal injury. Anything man-made, volcanoes will just shave away if it gets in their way.

Volcanic eruptions

Volcanic eruptions sound like a very unlikely event, almost like an asteroid falling on someone’s head. But it’s not that rare: around 50 of the active volcanoes erupt every year. Some, like Stromboli in Italy, are always active, while in other regions like the Pacific Fire Belt, volcanic eruptions are commonplace. Usually these are not big, spectacular eruptions, but a little spit, a little ash, a little lava. Nevertheless, people fall victim to them again and again: in the large outbreaks, but also in smaller ones again and again. The reason for this is that the area around volcanoes is very fertile and therefore popular for settlement – if an eruption comes as a surprise to the population, it may be too late to get to safety.
Since 1700, around 300,000 people have died in volcanic eruptions, 25,000 of them in the 1980s alone. Even if predictability is improving all the time: Large, massive eruptions claim more and more victims in heavily populated regions.
The immediate dangers of a volcanic eruption lurk less in the outflowing lava, which is usually quite slow. High numbers of victims cause pyroclastic flows from which one cannot escape. Lava and gravel landslides caused by collapsing craters can also bury entire towns. Mud avalanches, called lahars, composed of water, volcanic ash, and gravel, can bury large regions around a volcano under mud. And last but not least, stored gases can be released explosively.

How close is too close?

Volcanoes can be an interesting spectacle. In Iceland you can see the relatively harmless volcanoes very closely, in Guatemala hiking routes to the crater rim of active volcanoes are part of the normal tourist excursion program, and tours of Mount Etna are very popular. Especially gentle, effusive and long-lasting erupting volcanoes are suitable to look at. But caution is always required: If a volcanic area is closed, there are reasons.

Monitoring active volcanoes

In about 70 volcano observatories, the activities around volcanoes are observed intensively. Especially those that pose a great danger, such as Vesuvius in Europe, are continuously monitored.

In addition to monitoring, human action is required above all: what should happen if scientists predict an outbreak? How seriously this is taken and how early an evacuation is made can mean the difference between a manageable problem and an enormous humanitarian catastrophe.

Travel to volcanic regions

Volcanoes often announce their activities well in advance. If a volcano is observed particularly intensively, there is usually interesting activity there. In that case, it’s a good idea to follow the latest news and see if contingency plans are activated in a region. This usually happens well before a real risk arises, but it is intended to put the population on the alert.

If there are clear signs of an approaching eruption, holidaymakers should consider leaving the area. If you stay: As calmly as possible, simply do what is ordered by the local authorities.

Volcanic gases

Around a volcano, air measuring stations regularly sound the alarm: sulphur, particles, CO2 and too little oxygen – right next to a volcano, the air becomes thin for humans.
That’s why volcanologists who go near a lava flow wear appropriate gas masks, against which any FFP2 mask is airy, and of course protective goggles that fit tightly to the face. And if they come very close still protective suits….
A walk to an active lava tongue without such protection and the appropriate knowledge should definitely be avoided.

CO2 (carbon dioxide)

CO2 is produced with every combustion, as well as with a bubbling volcano in rough quantities. It is the gas that is known as the fuel of the impending climate catastrophe – and the gas that everyone produces when they breathe.
CO2 is heavier than air and can form a layer on the ground where it can accumulate in concentrations that are harmful to health. This can happen in the basements of breweries, but also in depressions on the rims of active volcanoes.

SO2 (sulphur dioxide)

SO2 can combine with water to form sulfuric acid. This is particularly dangerous where lava comes into contact with large quantities of water – e.g. when it enters the sea, when it rains or when it comes into contact with groundwater. The poison, which is highly harmful to humans, should not be inhaled – one of the reasons why the area around active volcanoes is often closed even when there is no longer any danger. Volcanologists only approach the critical zones with gas masks.

Acid rain can form from the released sulfur dioxide, which can rain down far from a volcanic eruption.

H2S (hydrogen sulfide)

The smell of rotten eggs that you can smell around volcanoes is due to the hydrogen sulfide in the air. The smell indicates an incipient unhealthy concentration of this extremely toxic gas, which fortunately rarely causes harm to humans when it occurs in nature: one automatically tries to escape the smell.

Creeping Death: Gas Leaks from Crater Lakes

Gases of volcanic origin can kill people in very unpredictable ways. CO2 can accumulate at the bottom of crater lakes. If it doesn’t combine with the water, it can lie underneath as a gas bubble and explode out in a volcanic tremor. Such an event killed 1700 people in Cameroon in 1986 who were poisoned by C02 creeping down the slope.
Volcanic gases claim individual victims when researchers or interested parties are exposed to high concentrations without protection. The only dead in the Ausbuch of Teneguia on La Palma in 1971 was a photographer who died in the hospital from symptoms of poisoning.

Volcanic Ash

“Lava ash? Yeah, we’re familiar with that here… (laughs) I mean, imagine coming home with your hair and face covered in ashes. Before you take a shower, you first clean up the ashes in the bathroom, then you get rid of them from your hair. There’s still a little bit left, but at least the ashes don’t trickle into your food anymore. And before you go to sleep, you shake the ashes out of your bed… after picking the last grains out of your teeth….”
(Lidia, Los Llanos, La Palma)

Every volcanic explosion is accompanied by ash. The resulting cloud can stretch several kilometers high and be carried hundreds to thousands of kilometers. Extreme amounts of ash can remain in the atmosphere for weeks and months and slow down the entry of sunlight, resulting in short-term climate changes in large regions.
Volcanic ash can therefore not only affect the immediate surroundings of a volcano, but also large airspaces: During the eruption of Eyjafjallajökull in Iceland in 2010 – still remembered by some – the entire northern European airspace came to a standstill for several days because the ash cloud was incompatible with engine safety.
Small ash particles are like glass, incredibly sharp-edged. These particles can become unhealthy for humans.