The Meteored meteorologist, José Miguel Viñas, has warned this Wednesday of the creation of lahars in western La Palma due to the heavy rains that are expected for this Thursday and Friday on the island and the accumulation of ash from the volcano.
East rain episode It will remain until Saturday and will be accompanied by winds from the west in high areas.
One of the problems caused by ash, pyroclastic material whose dimension is less than 2 millimeters, is its accumulation, says in a note Lorenzo Pasqualini, a geologist at Meteored.
When it is piled up for example on the roofs of buildings, its weight can cause collapses, and therefore it is important to remove it to avoid collapse.
If the volcanic ash mixed with rainwater, it can turn into mud that blocks roof drains and increases the weight of built structures, increasing the risk of collapse.
East mud it can clog sewers, and increase damage in areas affected by ashfall, causing flooding.
A more fearsome phenomenon caused by the combination of rains and volcanic ash are the so-called lahars, he says, a mud wash that occurs on the slopes of a volcano, formed by pyroclastic materials mixed with moving water, attracted by the force of gravity, towards the areas located at lower elevations.
This type of mud run usually occurs when there is a lot of accumulation of recently expelled pyroclastic materials in a mountainous area with steep slopes, and when there are very violent storms or sudden melting of glaciers.
On the slopes of volcanoes this type of flow can reach very high speeds and destroy anything in its path.
A “terrible example“de lahar is that of 1985 in Colombia, caused by the sudden melting of a glacier in the Nevado de Ruiz eruption, says Pasqualini.
In Italy, during the eruption that buried Pompeii in AD 79, such a mud wash buried the city of Ercolano.