The lava from Hawaiian volcanoes is so fluid because it is rich in basalt, a type of magma with low viscosity. The high temperatures and low silica content allow this lava to flow more easily than other types of lava.
Hawaiian lavas are primarily composed of basalt, a volcanic rock rich in iron and magnesium, but very low in silica. The key point is this low proportion of silica, as the lower it is, the more fluid the magma becomes, making it easy to flow. Alongside iron and magnesium, there is also quite a bit of calcium and sometimes a touch of titanium. This chemical combination, typically derived from magma that comes directly from the deep Earth's mantle, is what gives Hawaiian flows their liquid and fluid appearance as they slowly move down the volcanoes.
Hawaiian lava exits the volcano at particularly high temperatures, often between 1100 and 1200°C. And in the magma, the hotter it is, the more easily it flows. This high heat reduces the viscosity (resistance to flow) of the magma, making it very fluid, comparable to hot honey rather than cooled caramel. It is this intense heat that allows Hawaii's lava to race down the slopes so quickly and freely, forming long, fluid flows capable of traveling for kilometers.
The viscosity of lava directly depends on its silica content. Hawaiian lavas contain very little silica, often around 50% or less. This low concentration allows the magma to flow easily, like warm honey rather than a thick paste. Silica-rich lavas, on the other hand, become sticky and thick, trapping gases and causing explosive eruptions. In Hawaii, the fluidity of the magma promotes slow and steady flows, sometimes allowing the formation of long underground tunnels filled with fluid lava.
Dissolved gases act a bit like a carbonated beverage: the more there is, the more it bubbles and the easier it flows. When magma rises to the surface, these gases start to escape, creating small bubbles that make the mixture overall less dense and therefore more fluid. In Hawaii, these gases are often composed of water vapor, carbon dioxide, and sulfur dioxide. This explains why Hawaiian lava flows relatively quickly and smoothly, without violent explosions. Less gas trapped inside, less internal resistance, in short, super fluid lava that can meander peacefully down the slopes!
Beneath Hawaii, magma rises relatively quickly to the surface due to lower pressure than in many other volcanic regions. This low pressure allows the magma to flow smoothly through the rock conduits, without getting stuck underground for too long. The less time it remains trapped, the less it cools and thickens, so the more fluid it stays. As a result, Hawaiian volcanoes produce lava fountains or long and peaceful lava flows, rather than violent explosive eruptions caused by the buildup of high pressure.
Due to its low viscosity, Hawaiian lava can flow over great distances before cooling and solidifying, thus gradually shaping the landscape of these unique islands.
The shield volcano Mauna Loa, located in Hawaii, is considered the largest active volcano on our planet due to its massive volume, a significant portion of which lies beneath the ocean.
Kīlauea, one of the most active volcanoes in the world, located on the Big Island of Hawaii, has been erupting nearly continuously since its first scientific observation in 1823 until 2018, regularly shaping the surrounding landscape.
Typical Hawaiian lava flows are called 'pahoehoe,' which in Hawaiian means a smooth and undulating texture, in contrast to 'a'a,' which refers to rough and brittle lava.
The fluidity of Hawaiian lava allows it to flow quickly and form tunnels called 'tubular structures' or 'lava tubes.' The surface lava often cools faster than that which is flowing below, creating a solid crust that allows the hot magma to continue circulating, protected by this solidified crust. This gives rise to the underground tubes characteristic of Hawaiian volcanoes.
Certainly less explosive and violent than other types of lava, Hawaiian lava remains extremely hot (typically around 1100°C) and can cause burns or other severe injuries upon close contact. It is essential to maintain a safe distance and follow the guidelines provided during visits or observations.
The durations of Hawaiian eruptions vary greatly. Some may last for a few days or weeks, while others, like the continuous eruption of Kīlauea volcano from 1983 to 2018, can last for several decades due to a steady supply of fluid magma from deep within the Earth.
Hawaiian volcanoes are fueled by magma that is low in silica content, making it extremely fluid. The volcanic gases present escape easily, thus preventing the buildup of intense pressure that leads to explosive eruptions. As a result, Hawaiian lava typically flows in a steady and gentle manner.
Yes, other volcanoes produce basaltic lava similar to that of Hawaii, notably those located at mid-ocean ridges such as the Icelandic volcanoes or the Galápagos Islands. However, Hawaiian lava is particularly renowned for its exceptional fluidity associated with its specific chemical and thermal characteristics.
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