Difference between magma and lava - Definition

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Due to the large number of active volcanoes that exist in the world, it is likely that one of them is always erupting. Some volcanic eruptions tend to be more renowned, due to their intensity or the impact they cause, while others may rather go unnoticed. Precisely in those volcanic eruptions that are more recognized or mentioned, the error always arises of referring to magma and lava as the same thing, although in reality they are not.

To avoid confusion, from Ecologista Verde we will dedicate this article to explain in detail the difference between magma and lava. If you have your doubts about it, don't stop reading these lines.

What is magma

Let's start this article by understanding what magma is. Magma is simply defined as molten rock from the center of planet Earth. As a result of smelting, magma is a mixture of liquid substances, volatile compounds, and solid particles.

In itself, it is very difficult to define the composition of magma since it depends on factors such as temperature, pressure, minerals and more, but, in general terms, we can distinguish two types of magma according to its mineral composition. Let's see here:

  • Mafic Magmas: They are those that contain proportions of silica in the form of silicates rich in iron and magnesium and, in general, arise as a result of the melting of the heavy crust of the seabed. For its part, this type of magma is also called basic magma and, due to its low silica content, it is characterized by being fluid. As for its temperature, it is usually between 900 ºC and 1,200 ° C.
  • Felsic Magmas: In contrast to the previous one, they are those magmas that contain large proportions of silica in the form of silicates rich in sodium and potassium. They commonly originate from the melting of the continental crust. They are also called acid magmas and, due to their high silica content, they are viscous so they do not flow well. Regarding the temperature of felsic magma, it is usually between 650ºC and 800ºC.

As can be seen, both types of magma have high temperatures. However, when magma cools, it crystallizes, giving rise to igneous rocks. These can be of two types:

  • Plutonic or intrusive rocks, when magma crystallizes inside the Earth.
  • Volcanic or effusive rocks, when magma crystallizes on the earth's surface.

In this other article you can learn more about igneous rocks: types, characteristics, classification and examples.

Now the magma remains inside the volcano in a structure called magmatic chamber, which is nothing more than an underground cavity where the mass of molten rock is stored and is the deepest part of volcanoes. As for how deep the magma is, it is difficult to know, it is even difficult to detect those magmatic chambers that are at great depth. However, the magma chambers that have been found are between 1 and 10 kilometers deep. Finally, if the magma manages to ascend from the magmatic chamber through some conduit or chimney of the volcano, what is known as a volcanic eruption occurs.

To learn more about this topic, do not hesitate to read these other articles about Magma: what it is, types, where it is found and how it is formed and the Parts of a volcano.

What is lava

Having learned more about magma, we can move on to talking about what lava is. Lava is simply the magma that in the volcanic eruption reaches the earth's surface and that produces what we know as lava flows. Ultimately, lava is what we observe in volcanic eruptions.

Regarding its characteristics, both the composition of the lava and the temperature of the lava depend on the peculiarities of magma, although the temperature of the lava varies throughout its journey through the earth's surface. In particular, lava is exposed to two factors that magma is not: atmospheric pressure, which is responsible for releasing all the gases present in magma, and ambient temperature, which causes the lava to cool rapidly and as a result originate volcanic or effusive rocks.

Learn more by reading this other post about the Types of volcanic eruptions.

What is the difference between magma and lava

If you've come this far, you've probably already noticed the difference between magma and lava. Anyway, here we will make a brief summary of their main differences to clarify possible doubts. So, whenever you wonder if it is magma or lava, keep these aspects in mind:

  • Location: this is possibly the biggest difference between magma and lava. While magma is molten rock below the earth's surface, lava is magma that has risen and reached the earth's surface.
  • Exposure to factors: specifically, lava is exposed to factors specific to the earth's surface, such as atmospheric pressure and ambient temperature. On the contrary, magma being below the earth's surface, it is not exposed to these factors.
  • Rock formation: When magma cools, it does so slowly and deeply, resulting in plutonic or intrusive rocks. In contrast, when lava cools, it does so quickly and on the surface, resulting in volcanic or effusive rocks.

Now that you have learned what the difference is between lava and magma, we encourage you to continue discovering more about volcanoes. For this you can read our articles on How volcanoes are formed and Types of volcanoes.

If you want to read more articles similar to Difference between magma and lavaWe recommend that you enter our Nature Curiosities category.

  • Sigurdsson, H., Houghton, B., McNutt, S., Rymer, H., & Stix, J. (Eds.). (2015). The encyclopedia of volcanoes.
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