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Perigosos “cabelos” dourados surgem no vulcão Kilauea (Havai) (texto original em Inglês) - Notícia OVGA 15-06-2018

 

Este material, semelhante a cabelos, na verdade consiste em finos filamentos de vidro vulcânico conhecidos como Cabelo de Pelea e originou-se a partir da lava do Vulcão Kilauea, no Parque Nacional de Vulcões do Havai. Credit: Alamy

 

Golden, sharp strands of so-called goddess hair are covering parts of Hawaii's Big Island. But what are these potentially dangerous threads — called Pele's hair — and where did they come from?

The mats of Pele's hair — a product of the ongoing eruption from Kilaueavolcano — consist of thin glass fibers that form when gas bubbles within lava burst at the lava's surface, said Don Swanson, a research geologist at the Hawaiian Volcano Observatory.

"The skin of the bursting bubbles flies out, and some of the skin becomes stretched into these very long threads, sometime[s] as long as a couple of feet [0.6 meters] or so," Swanson told Live Science.

These gossamer strands are thin, just a micron (one-thousandth of a millimeter) or two in diameter, although some of them are coarser. "Often, they are really like human hair, so the name is very apt," Swanson said.

Cabelo de Pelea ao microscópio. Credit: U.S. Geological Survey

 

These strands of lava-turned-glass usually have a small sphere at the end, but this usually gets broken off, Swanson added. Pele's hair — named after Pele (peh-leh), the Hawaiian goddess of fire and volcanoes — is so lightweight that it usually gets blown downwind from where it formed. Because these glass fibers have sharp ends, they can be dangerous to pick up, Swanson noted.

In previous volcanic eruptions, Pele's hair has caused trouble for the many Hawaiians who collect rainwater for drinking water. These glass strands land in rainwater that falls on people's roofs and is then funneled into a catchment system. "If the filters aren't fine enough to filter out the hair, then you can get hair in the water," which can harm anyone who drinks it, Swanson said.

"Imagine inhaling tiny slivers of glass. That's what the Pele's hair is," he said. "It can inflame and irritate anything that comes in contact with it."

Moreover, there are cattle ranches downwind of Kilauea volcano. In the past, Pele's hair floated downwind and fell into the cattle's water troughs, where thirsty bovids slurped it up. This likely injured the cattle's esophagi and stomachs, Swanson said.

However, he hasn't heard any reports of people or cattle hurt by drinking water contaminated with Pele's hair from the current eruption, Swanson said.

Um tapete de cabelos de Pelea cobre esta paisagem no Havai. Credit: U.S. Geological Survey

 

Rather, Pele's hair has been more of a nuisance this time around, albeit a rather beautiful one, he said.

 "You can get drifts of Pele's hair that may be a foot or two thick interwoven with one another," Swanson said. "It can be quite striking.

Adenda OVGA:

Os cabelos de Pelea consistem em finíssimos filamentos de vidro vulcânico formados aquando da libertação de bolhas de gás dentro da lava. Depois de soprada pelo vapor da própria erupção e imediatamente solidificada, a lava muito fluida transforma-se num material vítreo (amorfo).

O vento frequentemente transporta as fibras leves para locais a muitos quilómetros de distância da sua origem, sendo comum encontrar cabelos de Pelea em lugares altos como nos topos de árvores, antenas de rádios ou postes elétricos (ver imagem abaixo).

Os cabelos de Pelea não existem exclusivamente no Havai. Podem ser observados próximo de outros vulcões no mundo, como no Masaya (Nicarágua), no Etna (Itália), no Erta’ Ale (Etiópia) e na Islândia onde são conhecidos como “nornahár” (“cabelos de bruxa”). Nos Açores foram observados no Vulcão dos Capelinhos (Faial).

Não é recomendável tocar em cabelos de Pelea, pois são muito frágeis e muito afiados, e os pedaços mais pequenos podem penetrar a pele. O seu nome refere-se a Pelea, deusa havaiana do fogo e dos vulcões.

Cabelos de Pelea numa antena de rádio no Havai. Credit: Wikipedia

 

Fonte: livescience

Redator: Pedro Correia (OVGA)