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Tectonic hazards

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Types of volcanic eruptions. During a volcanic eruption, lava, tephra (ash, lapilli, volcanic bombs and blocks), and various gases are expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different meta types of eruptions. The most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward.

Phreatomagmatic eruptions are another type of volcanic eruption, driven by the compression of gas within magma, the direct opposite of the process powering magmatic activity. Within these wide-defining eruptive types are several subtypes. Eruption mechanisms Volcanic eruptions arise through three main mechanisms: Hawaiian Peléan. Nepal earthquake: Rescue effort intensifies - BBC News. Rescue efforts in Nepal are intensifying after nearly 2,000 people were killed in the country's worst earthquake in more than 80 years. Many countries and international charities have offered aid to Nepal to deal with the disaster. Seventeen people have been killed on Mount Everest by avalanches - the mountain's worst-ever disaster.

The death toll could rise, as the situation is unclear in remote areas which remain cut off or hard to access. Many mountain roads are cracked or blocked by landslides. Scores of bodies have been ferried to hospitals in the capital Kathmandu, many of which are struggling to cope with the number of injured. More than 700 have died in the capital alone.

Medics are expecting a fresh influx of patients on Sunday as supplies run low. Rescuers in places used their bare hands to dig for survivors still buried underneath piles of rubble and debris overnight on Saturday. "We believe there are still people trapped inside," he told Reuters. Quake levels Nepal landmarks. Nepal earthquake: fears grow for remote villages as at least 4,000 confirmed dead. At least 4,000 people have been killed and more than 100,000 left homeless by the earthquake in Nepal, officials have said, as the search intensified for those in remote villages that are out of the reach of rescue teams. However, reports from the remote Nepalese district of Ghorka, close to the epicentre of Saturday’s quake, suggest the number of casualties could be fewer than has been feared – even if a high proportion of buildings were badly damaged.

Officials said on Monday the total number of dead and wounded in Ghorka was still unclear but, having had contact with most of their outlying administrators, they thought it would be “in the hundreds, not the thousands”. By late-afternoon, the overall confirmed total across the country was 3,922 dead and nearly 7,180 injured, with a further 85 dead in India. An avalanche triggered by the quake killed 18 people at Mount Everest’s base camp, while 85 people were killed in India and China. “It is not just the buildings that are in ruins. Footage emerges of Everest base camp avalanche.

Nepal earthquake: Doctors forced to operate in tents with hospitals overwhelmed as death toll rises – and aftershocks keep coming - Asia - World - The Independent. The worst earthquake to hit Nepal in 80 years has killed more than 3,200 people, injured more than 6,500 and reduced several World Heritage sites to rubble. Some of the city’s buildings were smashed to pieces, others tilted at crazy angles. Partial collapses exposed living rooms, furniture and belongings stacked on shelves. People wandered the streets clutching bedrolls and blankets.

Others sat in the street cradling their children, surrounded by plastic bags of belongings. Rescuers, some wearing face masks against the dust, scrambled over mounds of splintered timber and broken bricks looking for survivors. Care International, the humanitarian agency, warned that the death toll could climb much higher. Out in the countryside the situation was no better. “Many people have lost their homes,” said Chandra Lama, an English teacher. Loading gallery “The aftershocks keep coming, so people don’t know what to expect,” said Sanjay Karki, country head of Mercy Corps. Chile's Calbuco volcano erupts again. Chile’s Calbuco volcano erupted again on Thursday, sending dark bursts of ash and hot rock billowing 2.5 miles (4km) into the air and prompting officials to order a new evacuation of nearby residents. Thick clouds boiled out of 6,500-foot (2,000-meter) cone, bringing the threat of new, heavy ash fall over villagers struggling to clean up from two huge blasts last week.

The area was evacuated after the volcano first erupted last Wednesday afternoon, but many people had begun to return to their ash-drowned homes. The eruptions at Calbuco are the first in more than four decades. About 4,500 people have been evacuated since the volcano roared back to life on 22 April, sending ash about 11 miles (18km) into the sky.

The ash spread across the southern part of the continent, disrupting flights in Argentina’s capital, Buenos Aires. The director of the National Mining and Geology service said that new eruptions greater than those last week are not expected. Horror in Nepal's 'worst-hit' village - BBC News. My cameraman Sanjay Ganguly and I were the first journalists to visit what is reckoned to be the worst hit village in all Nepal. We'd travelled on a reconnaissance mission with two British Gurkhas. You can watch our report here but be warned, it is very upsetting. Until last week Langtang village was one of the most popular trekking destinations in Nepal. It was home to 435 people and 55 hotels and guest houses.

Now just one house remains. The earthquake triggered a catastrophic avalanche and landslide that submerged the village under a great plume of ice and rock. Satellite images taken five days after the earthquake show the entire hillside collapsed more than 700 metres (2,300ft) down onto the village. In Kathmandu a friend and colleague who works for the BBC Nepali Service, Surendra Phuyal, showed me a picture he'd taken when he was trekking in Langtang in September. Comparing his picture to our helicopter images of the area now, the epic scale of the landslide became apparent. Himalayan 'drop after Nepal quake' - BBC News. The height of a swathe of the Himalayas has dropped by around one metre as a result of the devastating Nepal earthquake, scientists say. But they add that the drop will roughly be balanced by slow uplift due to tectonic activity. And they have yet to analyse satellite images of the region in which the most famous Himalayan peak - Everest - is located.

However, there continues to be debate over exactly how tall Everest is. "The primary stretch that had its height dropped is a 80-100km stretch of the Langtang Himal (to the northwest of the capital, Kathmandu)," said Richard Briggs, a research geologist with the United States Geological Survey (USGS). The Langtang range is the region where many locals and trekkers are still missing, presumed dead, after the avalanches and landslides that were triggered by the 7.8 magnitude earthquake on 25 April. The satellite images they have analysed so far have focused on central Nepal, which was the hardest hit by the quake. Before and after images. Nepal earthquake: 'Million children left out of school' - BBC News. Nearly a million children in Nepal will not be able to return to school in the wake of last month's earthquake unless urgent action is taken, says Unicef. The international charity says nine out of 10 schools have been destroyed in the worst-affected districts.

Almost 24,000 classrooms were damaged or destroyed in the disaster that hit the country 12 days ago, it adds. Unicef is attempting to set up temporary learning spaces for children. Currently, all schools are closed in Nepal, although many of those still standing are being used as emergency shelters. They are due to reopen on Friday, 15 May. 'Protection' As the humanitarian and clear-up efforts continue, the charity says there is a desperate need to set up alternative learning spaces for children, not just for education but for their safety as well. "It protects them from exploitation and abuse because everybody knows what they are doing and where they are. Free schooling. Why was the earthquake in Nepal such a devastating event? Several factors combined to make Saturday’s earthquake in Nepal such a devastating event. The first was its basic magnitude. At 7.8 on the Richter scale, this was one of the most powerful earthquakes to strike the region in the past 80 years. In addition, it was a shallow event with a source that was only 11km below ground.

That has special consequences, according to David Rothery, professor of planetary geosciences at the Open University. “The shallowness of the source made the ground-shaking at the surface worse than it would have been for a deeper earthquake,” he explained. However, most areas touched by the earthquake lie on solid bedrock, said Rothery. As to the specific cause of the earthquake, it was triggered by the India tectonic plate, which is moving northwards at the rate of 5cm a year into central Asia. Why Nepal is so vulnerable to quakes - BBC News. The pictures emerging from the Nepalese capital, Kathmandu, are shocking. Durbar square, a Unesco World Heritage Site, has been reduced to rubble. The famous Dharahara Tower has been toppled to leave just a stump. Nepal is used to quakes – this is one of the most seismically active regions in the world. You only have to look at the Himalayas to understand that.

The mountains are being built as a consequence of the Indian tectonic plate driving under Central Asia (the Eurasian tectonic plate). The upward climb of Everest and its sister mountains is accompanied by numerous tremors. David Rothery, a professor of planetary geosciences, at the Open University, UK, commented: "The Himalayan mountains are being thrust over the Indian plate; there are two or three big thrust faults, basically.

Vulnerable buildings Initial estimates of casualties, even in the biggest quakes, usually start off small, and then grow. In the case of this quake, the fear will be that the final numbers could be quite high. Nepal earthquake: Rescuers forced to dig with their bare hands in search for survivors as images show damage to historic buildings - Asia - World - The Independent. Along with the huge loss of human life, critical infrastructure, homes and buildings have been destroyed by the magnitude-7.8 earthquake which struck before noon on Saturday, 50 miles outside the capital, Kathmandu. People were trapped under rubble after the powerful earthquake struck (Getty) Rescuers were forced to dig with their bare hands to reach survivors (Getty) Planes from neighbouring countries are now landing laden with aid, relief workers and doctors to help the impoverished country deal with the disaster.

Authorities say at least 2,152 people have died as a result of the earthquake, all but 60 of them in Nepal. In the capital, which was badly affected, at least 721 people were killed. India and China have already sent relief teams and medical supplies to Nepal, while Britain, the US and Pakistan have offered to help the rescue efforts. Loading gallery Powerful earthquake hits Nepal 1 of 44 The Dharahara tower before the earthquake... ...and after (EPA) Nepal was made vulnerable by more than its violent geology | Shaheen Chughtai. Kathmandu was ever a disaster-in-waiting. The densely populated capital of one of the world’s poorest countries clings to the slopes of the seismically unstable Himalayas. The city was nearly levelled and 8,500 killed in its last great earthquake 81 years before.

It had history. On Saturday the long-feared calamity struck. I first arrived in Kathmandu in 2007 to begin a new job with Oxfam. I’d been with the charity two years earlier and 1,000km west along the Himalayas as part of the international aid effort following the Kashmir earthquake. I saw towns there razed by the shifting tectonic plates that lie beneath that mountain range. With the Kashmir tragedy fresh in my mind, I remember looking at the thousands of flimsy shacks and hovels lining Kathmandu’s dusty slums and the sturdier, but still precarious, multi-tiered family homes, the cheaply built apartment blocks and ornate temples that collectively give the city its colourful, distinctive appearance. Nepal earthquake death toll expected to rise sharply. In the former royal city of Bhaktapur, dozens of traditional temples have been reduced to dirt and palaces have lost entire wings.

Damage to the famous Unesco-listed durbar squares of the city has been extensive; the Dharahara tower, one of Nepal’s most famous landmarks, was reduced to rubble, killing up to 180 people and leaving up to 200 people trapped inside. Masonry lay scatted across the stone paving. An ornate dragon’s head lay next to a chipped effigy of a god. Rescuers used their bare hands, with no protective gear or heat detectors, in their optimistic search for survivors. The narrow alleys would stop cranes, earthmovers or diggers reaching most of the houses that have collapsed, even if the aftershocks hadn’t scared workers out of even trying, said Shyam Adhikari, the local police chief. “Anyway, there’s not much point. There are some entire families buried. Nepal earthquake: Eight million people affected, UN says - BBC News.

Eight million people have been affected by the massive earthquake in Nepal - more than a quarter of the country's population - the United Nations says. International aid has started arriving but there is still huge need - 1.4 million require food aid, the UN said. The 7.8-magnitude quake hit Nepal on Saturday destroying buildings in Kathmandu and severely affecting rural areas across the region.

The death toll has risen to 4,310, with almost 8,000 injured, officials say. Nepal and surrounding areas have continued to experience aftershocks. Thousands in Kathmandu, Nepal's capital, spent a third night outside, too afraid to go back into their houses. Water, food and electricity are in short supply and there are fears of outbreaks of disease. The situation is critical in the remote rural regions towards the epicentre of Saturday's quake.

"It is very difficult to reach them," he added. Aid agency Oxfam says it is using land routes to get aid in and hopes to reach the epicentre region on Tuesday. Nepal earthquake death toll exceeds 6,000 with thousands unaccounted for. The death toll from the earthquake that struck Nepal on Saturday has passed 6,000, and many thousands are still unaccounted for. The latest police report has confirmed 6,260 fatalities, with about 14,000 injured and thousands still unaccounted for. The head of the European Union delegation in the country said 1,000 people from the EU were missing and 12 were confirmed dead. Although Nepal celebrated the rescue of two people pulled alive from the wreckage of buildings in the capital, Kathmandu, on Thursday, the sheer extent of the destruction of the 7.8-magnitude quake is becoming clear.

Thousands of villages have been devastated, with up to 90% of clinics and schools in some districts rendered unusable. Ram Sharan Mahat, the Nepalese finance minister, said at least $2bn (£1.3bn) would be needed to rebuild homes, hospitals, government offices and historic buildings. Other estimates have been higher. “There are still injured there who have not been treated. His baby survived the quake. 'I thought it was a dream': Nepal quake survivor recalls moment disaster struck.

Nepal quake: 'No chance' to find more survivors, as death toll rises - BBC News. Nepal earthquake: a disaster that shows quakes don't kill people, buildings d... Nepal quake: Why are some tremors so deadly? - BBC News. Explicit cookie consent. The economic impact of Nepal's earthquake. YouTube. This Interactive Map Shows Nepal Before and After the Earthquake. With two earthquakes in three weeks and a monsoon fast-approaching, Nepal is on a knife-edge - Comment - Voices - The Independent.

Iceland, Eyjafjallajökull - May 1st and 2nd, 2010. Nepal’s opportunity to seize the moment for the future of its people | UNDP in Asia and the Pacific. Top 10 active volcanoes to see up close | Travel. Earthquake measuring 8.5 magnitude shakes most of Japan. Mount Sinabung in Indonesia unleashes hot ash a mile into the air. Mount Everest, moved three centimetres due to Nepal earthquake.