Lava flows: what they are and types - Summary

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When a volcano erupts, we often hear a lot of terms that are often new to our vocabulary. Magma, lava, igneous rocks, cone, crater, chimney, fissures and more. Now, do you know what all these terms mean? In fact, you do not have to know it since they are not words that we use in our daily lives, unless you are fond of volcanology.

From our project, we want to help you understand the specific terminology of volcanoes so you can better understand when a specialist talks about the subject. For this reason, in this post by Ecologist Verde we will emphasize what are lava flows and what types are there. If you want to learn everything about it, this is the right post.

What are lava flows

To better understand this concept, we will start by first understanding what lava is. Lava is defined as magma, or mass of molten rock from within the Earth, that has risen up the volcano and has reached the Earth's surface. Broadly speaking, we can find two types of lava, the most abundant lava is that which comes from basic magma, with silicate content rich in iron and magnesium. On the contrary, there is the lava from acid magma, with high content of silicates rich in sodium and potassium.

In this way, lava flows are nothing more than a mantle of lava that was expelled during a volcanic eruption and flowing over the earth's surface. They end up forming channels or lava tubes because, when the volcano erupts, the contact with the atmosphere and the loss of heat to the ground causes the lava flows to solidify. Interestingly, there are simulations that make it possible to predict the path of lava flows and, in this way, it is possible to predict which regions will be affected by them.

If you want to know the Difference between magma and lava, do not hesitate to read Ecologist Verde's article that we recommend and watch our video.

Characteristics of lava flows

The characteristics of lava flows depend directly on the peculiarities of lava. Even so, we can highlight three characteristics that determine the speed of the lava flow:

  • Viscosity.
  • The fluidity of lava.
  • The properties associated with the percentage of silica it has.

As a result, those more fluid lavas originate long and thin castings while those more viscous lavas They produce castings of small extension and of great thickness. However, the speed of the pouring depends not only on the properties of the lava, but also on the topography and the force with which the lava is expelled from the volcano.

Usually lava flows they descend linearly down the slope of the volcano cone. Often times, the eruptions are not produced by the main crater but rather by fissures of the volcanic cone and, as a result, lava fields or blankets are produced.

It should be noted that during volcanic eruptions it can occur more than one lava flow. For example, at present the volcano that is found on the island of La Palma, belonging to the Canary archipelago, Spain, has been erupting for more than a month and, due to the large volume of lava emitted, has 10 lava flows.

Apart from the lava flows, there are more Parts of a volcano of the volcano that you can know here.

Types of lava flows

We can classify the types of lava flows according to the shape they take. Next we will develop the different types of lava flows that exist according to the different types of lava.

Pahoehoe lava flows

The pahoehoe lava, whose term comes from the Hawaiian pāhoehoe and means 'soft', it is also called roped lava. It is a type of basic lava that as a result originates a pahoehoe wash or rope wash. The surface of this casting can be wavy, smooth or folded in rope shape, hence its name. This characteristic is due to the agile movement of the lava under the crust.

Lava wash aa

Although the correct term is lava ‘A’āSince it comes from Hawaiian and means 'stony with rough lava' or 'burn', aa lava is used for practicality reasons. It is a type of basaltic lava that gives rise to the so-called laundry aa which, when cooled, presents a rough, loose and fragmented surface.

Its characteristic surface arises because the superficial lava is partially cooled, and due to the pressure exerted by the lava at high temperatures below it, it rapidly loses the gases it presents, deforms and fragments. The speed of the lava flows can be said to be slow, since it only advances from about 5 to 50 meters per hour. As a common factor, pahoehoe lava and aa lava come from basic magmas and with some fluidity. In addition, in their respective washes it is common to tube and channel network formation.

Block lava flows

These are lavas that are characterized by coming from intermediate-acid magmas. The flows of this type of lava, called block flows, when cooled present a fragmented surface in large irregular blocks with sharp edges.

Padded lava flows

In general, cushion lava comes from basic magma, although there are exceptions where it comes from intermediate-acid magma. Specifically, cushioned lava is that which is solidifies in an aquatic environment and, as a result, the laundry takes the form of rounded and stacked pads, hence the designation of its name. This type of wash can occur due to the eruption of underwater volcanoes or also due to the arrival of the lava flow, coming from a terrestrial volcano, to some body of water such as the sea, river or lake.

Learn more about the Types of volcanoes by reading this Green Ecologist article and take a look at this other to learn how volcanoes are formed and thus better understand the whole process.

If you want to read more articles similar to Lava flows: what they are and types, we recommend that you enter our category of meteorological phenomena.

  • Carracedo, J. C. and Perez-Torrado, F. J. (2015). Hazards associated with lava flows. Teaching of Earth Sciences.
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