STRANGER THINGS: 5 weird products of Kilauea volcano
Meteorologist/Science Writer
Friday, May 25, 2018, 11:33 AM - As the eruption of Hawaii's Mount Kilauea continues, we are seeing progressively stranger things from this volcano. Here are five of the strangest, and what they mean.
Fissures
The classic idea of a volcanic eruption typically brings to mind smoke and ash blasting kilometres into the sky, and thick lava overflowing from the summit of a cone-shaped mountain.
The eruption from Kilauea doesn't match this scenario, though, since the volcanoes of the Hawaiian islands are known as "shield volcanoes", which produce lava that is more fluid, and is more often seen erupting from cracks near the volcano's base.
These cracks are known as fissures.
Lava fountains from a fissure in Kīlauea Volcano's lower East Rift Zone, on May 19, 2018. Credit: USGS
Fissures are caused as lava forces its way through underground tubes, which connect the main magma chamber of the volcano with the ocean. Many of these lava tubes exist on the island, and some become sealed off as lava congeals and hardens. This forces the lava through the remaining tubes.
With the increased flow due to this new eruption from Kilauea, combined with few paths for the lava to follow, the added pressure in the lava tubes has caused some of the tubes that lie just beneath the surface to break open, exposing the lava to the open air.
The formation of these fissures shows just how intense this latest eruption is.
Lava Fountains
Helicopter overflight of Kīlauea Volcano's Lower East Rift Zone shows fountaining at Fissure 22, on May 21, 2018. Credit: USGS
The violent 'fountaining' of lava from these fissures is caused by the rapid formation and expansion of gas bubbles in the lava, which forces the molten rock from the narrow fissure opening at high speed. Fissure fountains can often reach up to 100 metres high, but can get up to 500 metres high at times.
There is so much gas in this fountaining lava that, standing near it, one can actually hear the lava hissing and fizzing, as if it were soda pop.
Vog and Laze
The threat from the Kilauea eruption is not only from the lava.
The gases being released from the lava fissures, directly into the air, include sulphur dioxide, which is hazardous on its own, potentially causing irritation of the skin, eyes, nose and throat for anyone coming into contact with it and breathing it in, and also breathing problems in higher concentrations. Combined with air, dust and water vapour, though, it produces sulphuric acid, resulting in a toxic layer of volcanic smog, or vog.
In addition, as lava reaches the shoreline and pours into the ocean, it evaporates large quantities of seawater to form what is known as lava haze, or 'laze'.
Lava enters the sea at two locations, on the morning of May 21, 2018. During this overflight, the wind was blowing 'laze' plumes along the shoreline toward the southwest. Credit: USGS
According to the USGS:
Laze is formed when lava enters the ocean. The interaction sends hydrochloric acid and steam with fine glass particles into the air. Laze drifts with the wind and can be a health hazard for people in the immediate vicinity of the plume, but it dissipates quickly downwind. Laze is irritating to the lungs, eyes and skin.
Fortunately, given Hawaii's location in the middle of the ocean, the trade winds tend to keep clean air flowing over the island, keeping vog and laze from accumulating and causing significant, long-term problems.
Lava Bombs
Lava fountaining out of a fissure reaches hundreds of feet in the air during a volcano outbreak in Pahoa, Hawaii, on May 19, 2018. Credit: John Linzmeier/U.S. Air National Guard/Handout
Lava from 'shield volcanoes' such as those in the Hawaiian islands, tends to be low-viscosity, so it flows almost as easily as water, only slowing as it cools, when it is in contact with air or water. Mixed in with this fluid lava, though, there can be large semi-solid chunks of molten rock. As the lava violently erupts from the fissures, these semi-solid chunks can be launched quite high into the air, to land some distance away.
These semi-solid chunks are known as volcanic bombs, or lava bombs.
As they fly though the air, their outer surface cools and hardens, and they take on aerodynamic shapes, like spheres or footballs. Depending on how long they spend in the air, and thus how long their surface cools, they can take on different forms when they hit the ground.
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'Spherical', or 'spheroidal', bombs form if the surface tension of the lava keeps it together into a roughly spherical shape. If a spherical bomb spins while it is in the air, it can form into a 'spindle' bomb, which is more football-shaped, with twisted ends.
'Breadcrust' bombs form as the outer layer cools, but then cracks apart as the interior continues to expand, so that the result looks like a loaf of freshly baked bread.
'Ribbon' bombs are produced when long streamers of semi-solid lava are ejected into the air, cooling into roughly cylindrical or ribbon-like shapes before they hit the ground.
So-called 'cow-dung' bombs form when the lava bomb does not cool significantly "in flight", so that it pancakes when it hits the ground, and ends up looking like a cow patty as it cools.
Lava bombs come in all sizes, from the tiny ones, less than ten centimeters wide, up to massive ones that can be up to 5 metres across and tip the scales at around 120 metric tons!
Eerie Blue Flames
When lava flows over land, you can see some very strange reactions as it consumes everything in its path. The video below reveals one of these strange reactions.
As reported by the USGS's Kilauea Photo & Video Chronology page, these blue burning flames were seen issuing from cracks in the lava on Kahukai Street, in Pahoa, Hawaii, during the overnight hours of May 22-23, 2018.
According to the USGS:
When lava buries plants and shrubs, methane gas is produced as a byproduct of burning vegetation. Methane gas can seep into subsurface voids and explode when heated, or as shown in this video, emerge from cracks in the ground several feet away from the lava. When ignited, the methane produces a blue flame.
With the eruption from Kilauea showing no signs of slowing down, at the moment, we may see even stranger things from this volcano. Keep an eye on our coverage for more.
