Title : Flashes coming from Bali's Mount Agung Volcano explained
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Flashes coming from Bali's Mount Agung Volcano explained
- The flashes were picked up by infra red sensors on a Japanese weather satellite
- Former Nasa scientist Roy Spencer shared the strange images via his website
- Geoscientist David Rothery believes lightening and cloud gaps are responsible
- He has also warned of immensely stupid attempts to scale the erupting volcano
Mysterious flashes coming from a volcano in Bali, spotted by satellite, may simply be down to gaps in cloud cover, an expert has claimed.
The bursts of light were picked up by 3.9 micron infra red sensors aboard the Japanese Himawari geostationary weather satellite
Described as 'hotspots', they appear to be emanating from the active Mount Agung which began erupting in recent days.
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Mysterious flashes coming from Bali's Mount Agung Volcano spotted by satelitte may simply be down to gaps in cloud cover, an expert has claimed. The bursts of light were picked up by 3.9 micron infra red sensors aboard the Japanese Himawari geostationary weather satellite
The images were shared online by former Nasa scientist Roy Spencer.
Writing on his website, the self-described climatologist and author described observing the mysterious night flashes, near Mount Agung.
Dr Spencer said: 'Thinking this was just sensor noise, I examined other areas for similar flashes, and saw none.
'But after reviewing nighttime imagery over the last week, I saw similar behavior during the early stages of the eruptions.
'It appears that the flashes are not lightning, but are either hotspots in the 3.9 micron portion of this product, a channel which is also used to detect wildfires, or some portion of the eruption cloud that has low emissivity at 3.9 microns.'
David Rothery, professor of planetary geosciences at The Open University, says that there are a number of obvious explanations.
Speaking to MailOnline, he said: 'No one should be surprised by "mysterious" infrared fluctuations on satellite images.
'The visibility of the incandescent vent and hot erupted material on the ground depends on gaps in the cloud.
'Some of the flashes might be lightning, which is common during ash eruptions because of the transport of particles from ground to air, where the electrical conditions are different, so discharge occurs.'
However, Dr Rothery warns that the worst may still be yet to come.
According to the Darwin Volcanic Ash Advisory Centre, ash is currently drifting south east at an altitude of 21,000 ft (four miles).
Officials have extended the closure of Bali's international airport for another 24 hours due to concerns that jet engines could choke on the thick volcanic ash, which was moving across the island, leaving 120,000 stranded visitors in need of shelter.
Volcanic tremors have also been ongoing since around 6am GMT (11.30am local time), and the risk of a major eruption has not passed.
The flashes were picked up by the 3.9 micron infra red sensors on the Japanese Himawari geostationary weather satellite and shared online by former Nasa scientist Roy Spencer
Volcanic tremors have also been sustained since around 6am GMT (11.30am local time), and the risk of a major eruption has not passed. This graph shows recent seismic activity in the region
Yet Dr Rothery has heard reports of people, including tourists, boasting of climbing the volcano in recent days.
He added: 'There is a major risk of being hit by falling rocks, or ‘volcanic bombs’.
'It look spectaculars and is exciting, but even small explosions can throw out brick-size bombs that will kill or main you.
'Even being within the 10 km (six mile) exclusion zone is immensely stupid, and puts others’ lives at risk too, because if the eruption intensifies there will be hot and devastating pyroclastic flows.
'Outside of the exclusion zone people are safe, and not placing a burden on the civil defence forces.'
Dr Rothery believes pyroclastic flows are virtually inevitable if the current eruption becomes as big as the 1963 eruption.
Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and volcanic gas.
Dr Rothery has heard reports of people, including tourists, boasting of climbing the volcano in recent days, which he has branded 'immensely stupid'
Dr Rothery believes pyroclastic flows are virtually inevitable if the current eruption becomes as big as the 1963 eruption. This image shows a pyroclastic flow during the August 7, 1980, eruption of Mount St Helens
They move at very high speed down volcanic slopes, typically following valleys.
Most pyroclastic flows consist of two parts: a lower (basal) flow of coarse fragments that moves along the ground, and a turbulent cloud of ash that rises above the basal flow.
Ash may fall from this cloud over a wide area downwind from the pyroclastic flow.
When the rate of emission of ash becomes too great to be sustained in a stable eruption column rising skywards, all or part of the rising column will collapse, and the hot ash will rush downhill and seep across the terrain.
Alternatively, pyroclastic flows may spill directly out of the crater.
That’s the main reason why the 10 km (six mile) exclusion zone around the volcano has been declared by the local authorities.
A climactic eruption like 1963 could occur at any time, and people within that zone will not have time to escape.
The episodes of intense sustained seismic tremor at the volcano that are still occurring suggest that the risk of a climactic eruption has not passed.
'WE RAN': SURVIVORS OF 1963 BALI ERUPTION RECALL TERROR
Bali's Mount Agung volcano last erupted in 1963. Gusti Nyoman Dauh, now 72, lived through it as a teenager.
From his makeshift shelter, he recalls the last time he had to run for his life as his house was flattened.
'It was around 11:30am, we immediately ran, we had nothing with us except the clothes we were wearing,' Dauh said
Gusti Nyoman Dauh, 72, says his house was flattened the last time Bali's Mount Agung volcano erupted in 1963
'I was afraid and panicked. Our house was flattened by the eruption. It was scary.'
In 1963 pyroclastic flows - a fast moving mix of gas and volcanic material - spread 13 kilometres from the crater.
'At night everything was shaking because of the earthquake, I evacuated on foot through dusty roads,' said Nengah Bunter, 70, at another evacuation centre.
'Mount Agung had been erupting for three months when the government evacuated us. The lava and rocks had already been flowing near my house.'
Survivors of the 1963 Mount Agung volcano eruption recall being evacuated 50 years ago, when the cascading ash, rocks and hot gas killed 1,600 people
Nyoman Lanus Kecil, 75, added: 'It started raining ash so I ran away. I heard there was a ship leaving for another island, but when I arrived there was nothing.'
Officials hope improved technology and early warnings this time mean a disaster on the scale of 1963 will be averted.
'During the 1963 Mount Agung eruption, obviously the technology was not as good as what we have now, there were no volcanologists urging people to evacuate, that's why the number of victims was high,' said Surono, one of the country's leading volcanologists, who like many Indonesians goes by one name.
Indonesia is the world's most active volcanic region with 127 active volcanoes.
The Southeast Asian archipelago lies on the Pacific 'Ring of Fire' where tectonic plates collide, causing frequent seismic and volcanic activity.
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