Following the eruption of the La Palma volcano, many people had many questions, all related to the characteristics of volcanoes and lava. One of the most frequently asked questions was what happens if the lava reaches the sea.
For this reason, we are going to dedicate this article to telling you what happens if the lava reaches the sea, what its characteristics are and what can happen.
lava characteristics
Inside the Earth, the heat is so intense that the rocks and gases that make up the mantle melt. Our planet has a core made of lava. This core is covered by crust and layers of hard rock. The molten material that forms is magma, and when it is pushed toward the Earth's surface, we call it lava. Although the two layers are distinct—the crust and the rock—they are both constantly changing: solidified rock becomes liquid and vice versa . If magma seeps through the crust and reaches the Earth's surface, it becomes lava.
However, we call the magmatic material that erupts from the Earth's crust and spreads to the surface lava. Lava is very hot, between 700°C and 1200°C. Unlike magma, which can cool quickly, lava is denser and therefore takes longer to cool. This is one of the reasons why it is very dangerous to approach the site of a volcanic eruption, even if it is only a few days later.
What happens if the lava reaches the sea
The lava flow from the La Palma volcano plunged into the sea, triggering an immediate chemical reaction. After falling from a 100-meter precipice, the volcanic material, at a temperature between 900 and 1.000°C, came into contact with water at 20°C. The resulting reaction was intense evaporation, because the temperature difference was so great that the lava was able to heat the water very rapidly and create clouds, much of which was water vapor. But even its main components—water, which contains not only hydrogen and oxygen (H₂O), but also other chemical elements such as chlorine and carbon—produced various gases and volatile substances.
The Canary Islands Institute of Volcanology (INVOLCAN) reports that these formed white clouds or plumes filled with hydrochloric acid, as had been observed from the beginning. Seawater is rich in sodium chloride (NaCl), and the main chemical process that occurs at the high temperature of the lava produces hydrochloric acid (HCl), in addition to the plume of water vapor. A drone with chemical sensors was used in the area to analyze the gas.
In addition, other compounds are produced, but from a safety standpoint they are not comparable to hydrochloric acid since, among other effects, they can cause skin or eye irritation. Therefore, it is advisable to stay away from the area where acidic vapors may be present. The same applies to exhaust gases.
The experts emphasize that this cloud has nothing to do with the huge volcanic plume: “There was a lot of sulfur dioxide (the main gas that helps us monitor the state of the eruption), carbon dioxide and other compounds emitted there, but in much higher".
The plumes of acidic steam produced by hot lava and the oceans also contain tiny grains of volcanic glass. You can read more about underwater volcanoes and their ecological impact.
After exposure to cooler environments and large quantities of water, lava cools very rapidly, causing it to solidify primarily as glass, which shatters due to temperature differences. The lava is generally very hot (over 100°C, the boiling point of water) and can be toxic in some cases. Once released into the atmosphere, it disperses and dissolves. There may be some risk at close range, but this area is obviously surrounded and protected for kilometers around , so it shouldn't be a cause for concern.
what happens to the water
The further you get from the lava flow, the more the water temperature gradually recovers. The heat from the lava boils water in direct contact with it at temperatures exceeding 100°C. The water evaporates, but as you move further away from the lava flow, the temperature gradually decreases.
The further you get from the lava flow, the more the sea temperature gradually recovers. Water is cooler than the lava flow, except in the contact zones where it evaporates immediately. In this context, it's interesting to understand how the Canary Islands formed, given that they are the product of similar volcanic processes; details of which you can find in this article on the formation of the Canary Islands.
As long as lava continues to flow into the sea and solidify, allowing islands to rise above sea level, the chemical reaction will continue. There will always be a layer of water in contact with the hot lava flow. As long as it keeps flowing there, this reaction will continue because that temperature difference will always exist.
What happens if the lava reaches the sea and gases are generated
The effects of gasification, or the release of gases from the lava flow into the sea, are therefore restricted to the contact zone between the lava and the sea, which is the area that undergoes evaporation. In principle, the effect of this erosion on the water tends to disappear or be greatly reduced with increasing distance.
Likewise, INVOLCAN experts warn that these columns of acid vapor are a definite local danger for people who visit or are in coastal areas where lava meets the sea.
Furthermore, they maintain that this steam plume is not as energetic as the plume from the volcanic cone, which is producing potent acidic volcanic gases. These gases inject enormous energy into the atmosphere, reaching altitudes of up to 5 kilometers. For a more comprehensive analysis of the volcanic phenomenon, you can consult this article that explains why volcanoes erupt.
INVOLCAN warns that inhalation or exposure to acidic gases and liquids can irritate the skin, eyes and respiratory tract, in addition to causing respiratory difficulties, especially in those with pre-existing respiratory conditions.
I hope that with this information you can learn more about what happens if the lava reaches the sea.