Volcanic bombs are shreds, “drops”, of incandescent lava that are expelled from the mouth of a volcano, even many kilometers away. They can have different dimensions, ranging from a few tens of centimeters up to many meters. In order to be defined as “bombs” the diameter must always be greater than 64 cm, otherwise they will fall into the category of slag or lapilli. Mount Etna is a volcano now “expert” in bombs. With each eruption it expels thousands of them and it is precisely these that create the fire show that so many of us love to admire.
Types of volcanic bombs
Volcanic bombs can be divided into three types, in general. Some cool during expulsion and therefore land already with a hard crust. Some arrive on the ground still soft and incandescent. Others are shaped during flight. This depends on the magma and the impact of the climate on the molten rock.
Bombs that cool down, once on the ground, remain hot only inside and actually crack on the surface, or break in two. The bombs that fall to the ground while still hot tend to pile up. For this reason they are also called “cow dung”, while the other type is called “bread crust”. The bombs that are shaped during flight, thinning due to the effect of the air on the surface, take the shape of enormous almonds and are truly giant projectiles.
Dangerousness of volcanic bombs
Volcanic bombs are one of the biggest dangers for tourists who love volcanoes. More lethal than lava itself, these flying molten rocks can strike and kill even several kilometers away from the crater. This is the reason why, during an eruption, you must ALWAYS climb together with an expert guide who you must listen to.
A guide will know where to stay in case of lava fountains (those that eject volcanic bombs to greater distances). In fact, on these occasions it is very important to know from which side the winds are blowing. Because if you are in favour of the wind you are right in the path of the bomb rain. The ideal, in the event of an eruption with lava fountains, is to admire the show from the valley, avoiding getting too close to the eruptive scenario.
Volcanic bombs on Etna
In the past, volcanic bombs expelled by the explosions of Etna have also caused victims. As many as 9 tourists were killed in September 1979, due to a sudden explosion from the Bocca Nuova crater which projected gigantic stones for kilometers.
Admiring volcanic bombs “in times of quiet” however is an emotion and a wonder that everyone should experience.
Obviously the highest number of volcanic bombs on Etna is at the base of the four summit craters which are literally surrounded by them. Many volcanic bombs can also be found near Montagnola, in some areas of Valle del Bove, at Monte Frumento delle Concazze, at the Escrivà Crater. The most “touristy” bombs are those that can be admired at the Silvestri Craters. In particular, on the smallest and most accessible crater of this buttonhole-group there are several examples of bombs, some large and perfectly intact, others broken or eroded by the climate. Tourists love take selfies near these enormous stones which explicitly describe the power and grandeur of nature. (photos by G Musumeci)