Lava is amazing. Molten rock that erupts onto the surface area at 1000’s of levels! Our mainly reliable world (save for the liquid outer core, but that steel, not lava) can melt but all that molten material isn’t the similar. Those distinctions in composition are what drives the different behavior of lava on the surface area.
There is a (mainly) straightforward romance involving lava composition and behavior. The a lot more silica (SiO2) in the lava, the “stickier” it is. This raise in viscosity signifies that lava goes from totally free-flowing to hardly-flowing. Distinct volcanoes will erupt different compositions of lava depending on how the rock melts at the volcano and how it adjustments as it will make its way to the surface area.
The composition isn’t the only component that adjustments the lava’s stickiness. The hotter the lava, the runnier it is. A lot more crystals in the lava? Stickier. A lot more drinking water dissolved in the lava? Runnier. A lot more bubbles forming? Stickier. The closing viscosity of the lava is a complicated mix of all these components, but composition definitely drives the bus.
Correct now, we have 3 spectacular eruptions happening throughout the globe that definitely clearly show off the kinds of lava eruptions. In Hawai’i, Kīlauea has a new lava lake at its summit Halema’uma’u Crater. On Sicily, Etna has been erupting extended, snaking lava flows. At the similar time, La Soufrière on St. Vincent has a squat lava dome forming.
Kīlauea’s Lava Lake
The surface area of the Kilauea Lava Lake witnessed on January ten, 2021. The cooler, hardened surface area can be witnessed on the proper. Credit rating: Rob Simmon, Planet.
Considering the fact that late 2020, Kīlauea has burst again to existence immediately after more than two decades of peaceful. The summit eruption has started to fill the deep crater that formed during the 2018 Reduced East Rift Zone occasions. In the procedure, a new lava lake (above) as founded alone at the summit and it is currently being fed by a vent on the side of the lake. Immediately after about a thirty day period of eruption, the lake is now more than 650 feet (200 meters) deep!
In this animated GIF (beneath) of the filling of the lava, you can see how fluid it is as a floating island of cooled lava moved around its surface area. You can also see how the surface area behinds like a layer of “plates” of lava that are developed and destroyed — a bit like a mini model of plate tectonics. The vent feeding the lava lake is around the base of the picture.
Animated GIF of thermal pictures from the new Kilauea lava lake. Credit rating: USGS/HVO.
Lava lakes involve small silica lava known as basalt. Now, by “small silica”, we’re nevertheless chatting 47% of the lava is created of silica together with factors like iron, magnesium, calcium and many others. This basalt has near to the most affordable viscosity and optimum temperature of any lava erupting on Earth right now and that permits for a lava lake to form as together as new lava is repeatedly fed.
Etna’s Lava Flows
The lava flows (proper side of summit) from Etna witnessed by Sentinel-2 on January 19, 2021. Credit rating: ESA.
On the other side of the globe, Etna on Sicily has been erupting vigorously so much this 12 months. The eruptions have manufactured explosions at the summit as effectively as lava flows that have headed down the eastern slopes. The eruption has also unfold ash on the slopes of the volcano.
Thermal picture of the lava flows from Etna in Italy on January 21, 2021. The lava flows clearly show up as brilliant in this picture. Credit rating: INGV Osservatorio Etneo.
The basaltic andesite lava erupting at Etna is to some degree a lot more silica wealthy than Kīlauea’s. This signifies it is stickier and tends to create Strombolian eruptions. These eruptions have explosions brought on by significant bubbles of fuel soaring by means of the pipe that sales opportunities from the resource of the lava underneath the volcano to the surface area. The lava is nevertheless runny more than enough to form lava flows from the vent as effectively and that’s what is happening at Etna proper now. The infrared picture from Sentinel-2 reveals the energetic flows coming down from the Southeast Crater.
La Soufrière’s Lava Dome
Ultimately, we get to lava domes. These are formed by even stickier lava that erupts like squeezing toothpaste out of a tube. The lava does get much and alternatively just “piles up” producing a thick dome. Volcanoes like La Soufrière on St. Vincent erupt andesite (not to be confused with the previously mentioned basaltic andesite) that may well have up to sixty five% silica. This will make it a lot stickier than the lava erupting at Etna or Kīlauea.
The 2020-2021 lava dome at La Soufrière on St. Vincent in the foreground, with the 1979 dome in the background. Credit rating: College of West Indies Seismic Exploration Heart.
The new lava dome forming at La Soufrière is more than 1,one hundred feet (380 meters) throughout and three hundred feet (ninety meters) thick. It started forming at the quite stop of 2020 and it was the 1st eruption at La Soufrière considering that 1979. Look at out this online video of a helicopter flight more than the increasing lava dome.
The domes steep sides and extraordinary thickness seems outstanding for andesite lava erupting when in comparison to the basalt lava of Kīlauea. However, the viscosity of lava goes up quick when a lot more silica is extra. The lava in the Soufriére dome may well be up 1000’s of moments stickier than the Hawaiian basalt. If you compare the much ends of the lava compositional spectrum — basalt and rhyolite — you come across that rhyolite is a billion moments a lot more viscous! Some rhyolite lava domes and coulees (kind of like a hybrid of a dome and movement) can be hundreds of feet thick.
Most eruptions of lava to form these characteristics are reasonably passive. When you might be thinking about volcanic hazards, lava flows are negative for properties and infrastructure but not folks. All of this variance in stickiness is what drives the different kinds of lava lakes, flows and domes.