Japan's Mount Ontake eruption: Fumes, smoke and ash hamper rescue efforts - video

Japanese rescue teams have spent a third day searching for survivors on Mount Ontake, trapped by Saturday's eruption.

Recovery efforts have been hampered by conditions as the volcano continues to shoot gas, rocks and ash into the air.

Hundreds of hikers were on the volcano when it erupted. At least 36 people are known to have died.

Rupert Wingfield-Hayes from BBC reports from central Japan.

NASA Landsat-8: Sakura-jima volcano

Sakura-jima volcano emits a dense plume of ash over the Japanese island of Kyushu. 

Currently Japan's most active volcano, Sakura-jima explodes several hundred times each year. 

These eruptions are usually small, but the larger eruptions can generate ash plumes that rise 3,800 meters (12,000 feet) or more above the 1,040-meter (3,410-foot) summit. 

This true-colour image was collected by the Operational Land Imager on Landsat 8.

Mount Rokatenda spews volcanic material - Palue island, Indonesia

Mount Rokatenda spews volcanic material as it erupts on Palue island, Indonesia, Sunday, Aug. 11, 2013. 

Nearly 3,000 people have been evacuated from the island, according to the National Disaster Mitigation Agency. 

The volcano has been rumbling since last October. (AP Photo)

A volcano on a tiny Indonesian island is spewing more hot ash and lava after causing six deaths over the weekend.

Command post official Mutiara Mauboi says more than 500 Palue island residents who earlier refused to leave the 3-kilometer (1.9-mile) exclusion zone around Mount Rokatenda have been evacuated to neighbouring Flores island. 

She says the search for the bodies of two children killed in an eruption early Saturday has stopped.

Government volcanologist Surono says the volcano's eruptions were smaller Monday but the potential danger remains high because the volcano is releasing hot gas clouds. 

He says molten lava and ash have covered most of Palue island in East Nusa Tenggara province. 

The island in eastern Indonesia has only a 4-kilometer radius.

Puyehue Volcanic Eruption in Chile

These photos show the dramatic effects of huge volcanic ash clouds being shot through by fierce lightning bolts at the recent Puyehue eruption in Chile.

Guatemala Volcano Erupts, 33,000 Evacuated: Erupting Volcano Del Fuego

Guatemala Volcano Erupts & 33,000 Are Evacuated: Photos Of Erupting 'Volcan Del Fuego'

The Guatemala volcano "Volcan del Fuego" erupted Thursday, forcing some 33,000 locals to flee the area, emergency services said.

Ash and smoke were spewed into the sky as the volcano began to erupt. The volcano lies 25 miles southwest of Guatemala City and began to send a cloud of ash into the sky in the early afternoon, Sergio Cabanas, director of emergency response in Guatemala's CONRED emergency agency, told Reuters.

Nearly 8,000 people have already been evacuated and almost 23,000 are awaiting evacuation, he added.

Guatemala has four active volcanoes, Reuters said, and the 2010 eruption of Pacaya covered 25 miles of Guatemala City with ash. Airports were closed and hundreds of families were evacuated.

Cabanas additionally said that 17 villages near Guatemala City were evacuated in the biggest such operation the country has ever seen.

Although the volcano is just six miles from Antigua, a popular tourist destination, Antigua was not in the evacuation zone according to NBC News.

The "Volcano of Fire" has spewed lava that billowed 2,000 feet down its slope, BLIPPITT reported.

"A paroxysm of an eruption is taking place, a great volcanic eruption, with strong explosions and columns of ash," Gustavo Chicna, a volcanologist with the National Institute of Seismology, Vulcanology, Meteorology and Hydrology, said to BLIPPITT.

He said the ash from the volcano was nearly half an inch thick in some areas and the government's disaster agency added that homes and buildings were covered with ash miles away.

This is the fifth time Fuego has erupted this year, but its biggest eruption since 1999, a Guatemalan scientist told NBC News.

Teresa Marroquin, a Guatemalan Red Cross coordinator, told NBC News that the group has set 10 emergency shelters and is sending hygiene kits and water.

"There are lots of respiratory problems and eye problems," she said.

Chinca added that "it's almost in total darkness" near the living mountain.

Icelandic Tectonic Plate activity may trigger Katla

As scientists and air travellers alike keep a close eye on Iceland's ongoing volcanic eruption, some reports suggest that another, much bigger, volcano could stir in the near future.

Katla is Eyjafjallajokull's more active neighbour, and scientists believe that there may be a link between the two volcanoes.

This link has not been physically proven, explains Magnus Tumi Gudmundsson a geophysicist from the University of Iceland.

A circumstantial, historical connection "is putting people's eyes on Katla," he says.

"We know of four Eyjafjallajokull eruptions in the past [dating back to AD 500] and in three out of these four cases, there has been a Katla eruption either at the same time or shortly after.

"By shortly, I mean timescales of months to a year. "We consider that the probability of Katla erupting in the near future has increased since Eyjafjallajokull went."

Kathryn Goodenough from the British Geological Survey points out that, as yet, there is no physical explanation for this apparent link.

It seems that when Eyjafjallajokull goes off, Katla tends to follow. "Scientists don't yet know what the connection is," she says. "But we know there are fissures running between the two volcanoes. And they're quite close to each other.

"They're also being subjected to the same tectonic forces. So the chances are that if magma can find a pathway to rise beneath one of them, it can find its way to rise beneath the other."

Researchers do know that the two volcanoes have separate magma chambers, but many suspect that these chambers are physically linked in some way, deep beneath the surface of the Earth.

"But this is only speculative," says Dr Goodenough. "We don't have geophysical evidence that makes that clear."

LIVE Webcam Views of Volcano Eyjafjallajokull erupting

Click on the picture or on this link for Live Webcam video Views of Volcano Eyjafjallajokul

Iceland Volcano eruption of Ejyafjallajökull pre-requisite for massive Katla eruption

Live Webcam view Ejyafjallajökull

The eruption of Ejyafjallajökull, it is feared, may continue for weeks, months or even longer, disrupting air traffic whenever the wind blows its ash into flight paths: last time it blew up, in 1821, it went on for more than a year.

The real fear is that it may well be followed by another massive volcano, Katla, some five times bigger, which would spew out far more of the stuff and could therefore cause far greater chaos.

Every time Ejyafjallajökull has blown its top since the Vikings first arrived on the island in the ninth century, Katla has swiftly followed.

Vulcanologists say these could just be the opening volleys of a decades-long barrage, as climate change takes hold. “Global warming melts ice and this can influence magmatic systems”, Dr Freysteinn Sigmundsson, of the Nordic Volcanological Centre at the University of Iceland, told Reuters. “Our work suggests that eventually there will be either somewhat larger eruptions or more frequent eruptions in Iceland in coming decades.”

The volcano in Eyjafjallajokul, Iceland

Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul, Iceland.

Friction between the ash particles in the volcanic cloud creates enormous amounts of electricity that sparks and discharges around the crater.

The same electrical build-up is a danger to aircraft flying through volcanic ash and can cause the aircraft fuselage to glow. This effect is similar to St Elmo's fire.

Danger to Aircraft Engines
The other danger to aircraft engines is the adverse effect that volcanic ash has inside the modern aero engine, primarily in jet engines. The high temperatures and compression that is essential for propulsion in jet engines, melts the silica in the ash and converts into a sticky goo that clogs essential fuel jets, inlets and outlets.

The struggling engines can generate excess amounts of unburnt fuel, which escapes and ignites as it leaves the engine. This gives the impression of an engine fire but it is really a fire in the exhaust jet.

The next stage occurs when the jet engine becomes so clogged with sticky volcanic ash that it 'flares out' or extinguishes and shuts down. This can happen to all onboard aircraft engines within a very short space of time.

Re-starting a Jet Engine
Re-starting a jet engine in mid-flight is a standard procedure for aircraft pilots but when all your engines are out, it becomes much more stressful. Especially, if the engines are so clogged with sticky goo that the fuel cannot get through to the combustion chambers.

The problem with this scenario is that the sticky ash goo that clogged and stalled the engines is still present and it will continue to prevent the engine from re-igniting.

BA Flight
In the, now infamous, BA flight in which this scenario happened, the passengers and crew were fortunately saved by a number of lucky coincidences.

Once all the engines 'flared out', the outside temperature at high altitude quickly cooled the inside structure and the sticky goo quickly became brittle, causing pieces of it to break off, leaving a sufficient number of fuel jets clear to re-start the engines.

Once the aircraft was clear of the volcanic ash cloud and with the engines restarted, they were able to make a safe landing.