Saturday, October 09, 2021

Satellite captures rare weather phenomenon following volcanic eruption

By Maura Kelly, AccuWeather, Accuweather.com



A bullseye-shaped cloud was the product of a rising column of superheated ash and gases known as the eruption column on October 1 as part of the Cumbre Vieja volcano eruption on La Palma, one of the Canary Islands. Photo courtesy of NASA

Oct. 9 (UPI) -- The Cumbre Vieja volcano, located on the Spanish island of La Palma, has been erupting since the middle of September.

In addition to destructive lava flows and airport closures, the volcano produced a mesmerizing cloud formation during its eruption Monday.

On Thursday, the La Palma airport was closed for the second time in about two weeks as ash and dust accumulated on the runway.

The latest eruption forced the air above the volcano upwards. This was followed by circular ripples spreading out from the volcano, which could be seen on satellite and was caught on video by bystanders.

Meteorologists have given this weather phenomenon a name: gravity waves.


AccuWeather meteorologist Renee Duff explains that gravity waves occur when air is displaced from a calm state.

"As this air is pushed upward, it wants to sink back down in order to remain in a state of equilibrium," stated Duff. "It may take many up and down waves for this state to be reached."

In this case, the waves were made visible by clouds forming, as the air rose and became moist, creating the repeating pattern, like seeing the ripples in the water after dropping a stone in a pond.

Volcanic eruptions aren't the only mechanism that can create gravity waves.


"In the atmosphere, the 'stone' disrupting otherwise calm or stable conditions can be a severe thunderstorm, winds blowing over mountains or cold fronts," Duff said.

The gravity waves satellite photo wasn't the only impressive picture taken of the volcano from above. Planet Labs, Inc., which operates the largest earth observation fleet of imaging satellites, took a stunning closeup of the same day, in which not only the eruption is visible but also the lava which reached the coast last week.

Thousands of residents have been evacuated in the Canary Islands, located off the northwestern coast of Africa, since the Cumbre Vieja volcano began erupting Sept. 19. Hundreds of buildings and farms have been destroyed by rounds of lava, but one "miracle house" survived. The eruption came with dramatic footage of lava devouring a pool, filmed via drone.

On Saturday morning, the northern face of the volcano partially collapsed.


Volcano island flights resume after ash closed airport

Issued on: 09/10/2021 -
Two new lava flows emerged from the Cumbre Vieja volcano on Saturday
 Luismi Ortiz UME/AFP


Madrid (AFP)

Flights to and from La Palma in Spain's Canary Islands resumed Saturday after the airport reopened following a 48-hour closure due to volcanic ash, airlines and the airport authority said.

Clouds of thick ash from the volcano had shuttered the airport on Thursday morning for the second time since the September 19 eruption on La Palma, one of the Spanish islands off the northwestern coast of Morocco.

"La Palma airport is back in operation," Spain's AENA airport authority tweeted, with local Canaries airline Binter confirming it had resumed flights several hours later.

"Binter has resumed its flight schedule with the island of La Palma following an improvement in weather conditions and the ash cloud," an airline statement said.

Thick ash had forced the airport to close down on September 25 but although it reopened 24 hours later, it was three days before flights resumed.

It has been almost three weeks since La Cumbre Vieja began erupting, forcing 6,000 people from their homes as the lava scorched its way across 1,200 acres of land.

Earlier on Saturday, part of the volcano's cone collapsed, sending new rivers of lava pouring down the slopes towards an industrial zone.

"It seems part of the cone has collapsed... giving way to two different lava flows," volcanologist Stavros Meletlidis of Spain's National Geographic Institute told RNE radio.

He said one had opened a new path, while the other was following the path of an earlier flow "but with a higher volume of lava, looking like it will overspill the old flow at some point."

Miguel Ángel Morcuende, technical head of the Pevolca volcanic emergency committee said they were concerned about one of the flows that was approaching the Callejón de la Gata industrial estate, which includes warehouses and businesses.

"There is a large amount of lava there," he told reporters.

- Lava delta at risk of collapse -

Experts also said there was a risk that the lava delta, now stretching 80 acres (32 hectares) into the sea, could collapse as it reached the outer limits of the island's coastal shelf.

"Having reached the limit of the coastal shelf, if it continues to advance, its crust could collapse which could cause the abrupt release of gases, magmatic explosions and the generation of waves," said María José Blanco, the IGN's director in the Canary Islands, speaking at the same news briefing.

A costal or insular shelf is the underwater landmass surrounding an island, which extends from the shore to a depth of about 100 fathoms (about 180 metres or 600 feet) after which there is a sudden steep descent.

According to the latest snapshot from the EU's Copernicus satellite -- taken before the overnight events -- the lava had covered almost 1,200 acres (480.5 hectares) of land and destroyed 1,149 properties.

It has also destroyed huge swathes of banana plantations -- the chief cash crop on La Palma.

"New lava flows have mainly damaged agricultural areas now totalling 120 hectares of crops (300 acres), half of them bananas," Pevolca said on Friday.

Dozens more earthquakes took place overnight, including one with a magnitude of 4.3, the IGN said on Twitter.

© 2021 AFP

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