Glaring red lava shoots into the dark night sky in a wide arc. A fantastic sight. However, for the people living in close proximity of an erupting volcano, this spectacle is highly dangerous.
To be precise, during an eruption, the earth spits molten rock and hot gasses. About 100 kilometres below the earth‘s surface, there are temperatures of up to 1,300 °C. The rocks melt releasing gasses, which, in turn, increases the pressure inside the magma chambers drastically. Once this pressure gets too high, the liquid mass searches its way to the surface of the earth. During that, the magma uses cracks and fissures along the borders of the continental plates.
Everywhere on the earth there are volcanoes. Scientists assume that there about 1,500 active volcanoes around the globe. There are about 50 to 60 eruptions all over the world each day. However, not all volcanoes are the same. Volcanologists classify volcanoes according to the their outer shape, their magma supply system, the location where they arise, they type of their activity as well as to their condition. This rapidly leads to several dozens of different volcano types. Stratovolcanoes, shield volcanoes and cinder cones are particularly widespread. However, also in the oceans there many so-called submarine volcanoes the number of which can only be vaguely estimated.
The volcanic belt with a length of about 40,000 kilometres encircles the Pacific Ocean and runs from Chile, across northern Alaska and Japan to Southeast Asia and to the Pacific Islands. 90 percent of the globally active volcanoes are located along the ring. The friction between the Pacific Plate and the surrounding plates generates heat and pressure that melt the rocks. On the other hand, cracks occur and those are used by the magma for its way to the surface.
The most devastating eruption since the beginning of the recordings was the eruption of the Tambora on the Indonesian island of Sumbawa in the year 1815, when about 90,000 people died. Maybe you remember the eruption of the volcano Eyjafjallajökull on Iceland in the year 2010. The emitted volcanic ash rose up several kilometres into the sky so that air traffic had to be stopped in large areas of Northern and Central Europe. The most active volcanoes in the world are the Kilauea in Hawaii and the Stromboli on the eponymous Italian island north of Sicily. For decades, both volcanoes have been spitting lava which either remains in the crater or flows into the sea.
It‘s no question: volcanic eruptions are brutal and devastating. However, people also benefit from the volcanoes in many ways. So, the Hawaiian chain of islands is of volcanic origin – there, people live on cooled off lava that turned into rock. Many volcanic rocks are used as construction and industrial materials. Basalt is a special volcanic rock which was formerly used for paving roads. The lightweight pumice is used for refining clothes. Minerals like sulphur and nitre are processed to obtain gunpowder and fertilizers. These and other minerals also guarantee that volcanic soils are extremely fertile and therefore perfectly suitable for farming. Probably the most pleasant side effect of volcanism are thermal springs that have an extremely positive impact on human health. The minerals in the hot water help with skin diseases and muscle pain, depressions and internal diseases.