Types of Lava

LET US END THIS YEAR WITH A BANG!

Happy holidays! We recently have finished the types of magma. Magmas are hot fluid or semifluid material below or within the earth's crust but is it still a magma when it burst out of its chamber. We are discussing the different types of lava, the molten rock that comes out from the volcano. What are we waiting for? Let us start.

Several types of lava are present in different type of volcano.

The type of lava coming out of a volcano depends on its mineral content. Some lava is very thin, and can flow out of a volcano in great rivers that go for dozens of kilometers. Other lava is very thick, and only flows for a short distance before cooling and hardening. And some lava is so thick that it barely “flows” at all, and can plug up the plumbing of a volcano.[1]

The main types of lava have been given Hawaiian names, because of the volcanic nature of the Hawaiian islands.[1]

TYPES of LAVA

A'a

Aa Lava

(https://www.universetoday.com/29655/aa-lava/)

Aa forms when lava flows rapidly. Under these circumstances, there is rapid heat loss and a resulting increase in viscosity. When the solid surface crust is torn by differential flow, the underlying lava is unable to move sufficiently rapidly to heal the tear. [2]

Pronounced “ah-ah”, this is a basaltic lava that doesn’t flow very quickly. It looks like a slowly moving mass of hot jello, with cooler, rough surface. Once it hardens, the sharp spiny surface of a’a lava is extremely difficult to walk across. These types of lava erupt at temperatures above 1000 to 1100 degrees C. [1]

Pahoehoe

Pahoehoe lava

(http://www.decadevolcano.net/photos/keywords/pahoehoe_lava.htm)

Pahoehoe forms when lava flows more slowly. Under these circumstances, a well-developed skin can form which inhibits heat loss. When a tear in the skin does form, it is readily healed. Both magma discharge rate and the steepness of the slope over which the lava flows affect the flow rate. Thus aa lavas are associated with high discharge rates and steep slopes while pahoehoe flows are associated with lower discharge rates and gentle slopes. [2]

Pronounced "pahoeyhoey", this type of lava is much thinner and less viscous than a’a. It can flow down the slopes of a volcano in vast rivers. The surface of the lava congeals into a thin crust that looks very smooth. Pahoehoe lava can also form lava tubes, where the rock hardens around a fast-moving liquid core. When that core flows out of the tube, a long tunnel remains. Pahoehoe erupts at temperatures of 1100 to 1200 C. [1]

Pillow Lava

Pillow lava

(https://blog.education.nationalgeographic.org/2016/05/10/scientists-go-deep-deeper-deepest/2016-deepwater-exploration-of-the-marianas-3/)

Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in diameter. [3]

Pillow lava is typically found erupting from underwater volcano vents. As soon as the lava contacts the water, it’s cooled down and forms a hardened shell. As more lava issues from the vent, the shell of lava cracks and more “pillows” come out of these cracks.[1]