The world is full of natural hazards, from volcanoes to floods and storms. But where is the risk to human life greatest?
Most of us have been caught out by the weather, whether we got soaked to the skin in a storm or burned red by the sun. But there are places in the world where Mother Nature really goes in for the kill. From deadly storms to volcanic eruptions, there are threats everywhere.
Of all Earth's danger zones, which is the most deadly?
Let's break it down into the four elements to find the deadliest places on Earth.
A tidal whirlpool in the Saltstraumen, Norway (Credit: Cephas Picture Library/Alamy)
A tidal whirlpool in the Saltstraumen, Norway (Credit: Cephas Picture Library/Alamy)
Water
Water has obvious perils for us, because we are pretty poorly adapted to an aquatic environment. Despite our proficiency with boats, the International Maritime Organization still reported 1,051 deaths at sea in 2012, though only a small proportion were a direct result of the waves.
Most tsunamis – 71% according to the US National Weather Service – occur in the Pacific Ocean
Some waters are more dangerous than others, thanks to unique geographical features that boost their power. The Saltstraumen strait in Norway has earned a fearsome reputation for having the strongest currents on Earth. But the home of the world's most powerful whirlpool has now been so thoroughly studied, tourists can traverse it in an inflatable boat with a knowledgeable skipper.
It is perhaps on dry land then that water is a greater force to be reckoned with. For those living by the coast, inundation by sea water is a particular danger. The Maldives, a group of low-lying islands and atolls in the Indian Ocean, have also been called "the ephemeral isles" because they are so vulnerable to rising sea levels. The risk rises every year as our climate continues to change.
The hazard peaks when water levels rise suddenly, during a tsunami or storm surge.
The 2004 Indian Ocean tsunami was devastating (Credit: Mark Pearson/Alamy)
The 2004 Indian Ocean tsunami was devastating (Credit: Mark Pearson/Alamy)
A tsunami is the sudden displacement of water causing a colossal wave, or series of waves, and can have devastating consequences. Most tsunamis – 71% according to the US National Weather Service – occur in the Pacific Ocean. However, those generated by earthquakes can occur in any subduction zone, according to Thorkild Aarup, head of the Tsunami Unit at the Intergovernmental Oceanographic Commission of UNESCO.
The summer flood on China's Yangtze River in 1931 is thought to have killed millions of people
There are global tsunami warning and mitigation systems in place to protect people from these life-threatening events. But in some places, the warning times are as short as 20 minutes, so tsunamis can still claim many lives.
In 2004, the deadliest tsunami in recent history claimed up to 280,000 lives across 15 countries, after an earthquake struck off the coast of Sumatra, Indonesia. That death toll is so high, it is hard to comprehend. Yet even more lives have been lost to flooding rivers.
The summer flood on China's Yangtze River in 1931 is thought to have killed millions of people, though official records downplay the casualties. Heavy snowfall that year was followed by thawing and abnormally heavy rainfall, resulting in arguably the worst natural disaster on record.
Today, billions of people still live on flood plains next to China's biggest rivers and flooding is a growing concern as our weather patterns change.
Lake Nyos in Cameroon holds dangerous amounts of carbon dioxide (Credit: jbdodane/Alamy)
Lake Nyos in Cameroon holds dangerous amounts of carbon dioxide (Credit: jbdodane/Alamy)
Air
A number of "killer lakes" have been found in Africa, but it is not the water that is the worry.
Lake Nyos in Cameroon and Lake Kivu, on the border of the Democratic Republic of Congo and Rwanda, both harbour an invisible danger. These lakes sit on areas of volcanic activity where carbon dioxide leaks from beneath the ground.
Cape Denison in Antarctica is, on a year-round average, the windiest place on Earth
During a "limnic eruption", the carbon dioxide bursts out from the bottom of the lake to form a cloud. Because the gas is heavier than air, it descends, pushing oxygen away and suffocating any life in the area. After twoeruptions in the 1980s killed over 1,700 people and 3,500 livestock in Cameroon, experts devised methods to safely and regularly de-gas the lakes, using pipes and siphons.
A potential disaster has been turned on its head at Lake Kivu, where there is also methane gas leaking from beneath the earth. A project has been established to use the siphoned gas for energy and bring electricity to millions of people.
But it is not just gases that can kill. The air itself can dish out deadly punishment when winds become brutal.
Haiti is extremely vulnerable to hurricanes (Credit: SPACE BY NASA/Alamy)
Haiti is extremely vulnerable to hurricanes (Credit: SPACE BY NASA/Alamy)
Cape Denison in Antarctica is, on a year-round average, the windiest place on Earth. Unsurprisingly, it is uninhabited. However, seasonal storms cause devastation in populated areas worldwide.
The most intense storms are not necessarily the deadliest
The strongest storms form over warm oceans north and south of the equator. Here, the trade winds are boosted by the change in pressure and spun by the Coriolis effect, creating rotating weather systems known variously as hurricanes, cyclones and typhoons.
When it comes to such storms, Haiti is considered the most vulnerable island in the Caribbean. Not only does it lie in a hurricane highway, but the poverty-stricken country lacks resilience. Settlements are built on floodplains, natural defences like forests have been degraded, and the economy is not stable enough to fund flood defences or warning systems.
This explains why the most intense storms are not necessarily the deadliest.
The aftermath of the 1906 San Francisco earthquake (Credit: Glasshouse Images/Alamy)
The aftermath of the 1906 San Francisco earthquake (Credit: Glasshouse Images/Alamy)
Jörn Birkmann is an expert in the risks of natural disasters at the University of Stuttgart, Germany. He says that cyclones are dangerous because they are hard to predict.
The worst loss of life due to a cyclone happened in November 1970
"It is important to mention that most likely cyclone tracks will change their spatial pattern," he says. "That means cyclones will occur in some regions which have not seen cyclones before or only very few. These regions are highly at risk, since people and communities have no or very [little] knowledge on how to prepare for cyclones."
Birkmann is part of the team that compiles the annual World Risk Report published by the United Nations University. It highlights the countries that are most vulnerable to natural disasters, considering both their exposure and resilience, with the intention of focussing global efforts to protect them.
In 2016, Vanuatu topped the list. More than a third of the island nation's population are affected by natural disasters each year. In 2015 an earthquake, volcanic eruption and severe Cyclone Pam all hit within just a few weeks and 11 people were officially reported dead.
This relatively low death toll is testament to global efforts to protect people from natural disasters: both during, with improved infrastructure, and after, with better aid efforts. For comparison, the worst loss of life due to a cyclone happened in November 1970, when Bangladesh was hit by the Bhola cyclone. As many as 500,000 people died.
Part of the San Andreas Fault in California (Credit: Nik Wheeler/Alamy)
Part of the San Andreas Fault in California (Credit: Nik Wheeler/Alamy)
Earth
If there is one thing that ties the world's deadliest destinations together, it is tectonic activity.
The Earth's crust is made up of moving plates, and where they move against each other, potential energy builds. When this energy is released, the ground cracks and a seismic wave is thrown out, shaking the surface of the Earth in violent quakes.
Eight of the world's ten most vulnerable cities to natural disaster are in the Philippines
The deadliest earthquake on record was the 1556 Shaanxi earthquake in China, with an estimated death toll of over 800,000. Since earthquakes also trigger tsunamis, it is fair to say they give floods fierce competition for the world's deadliest natural disasters.
The San Andreas Fault, where the Pacific Plate slips alongside the North American Plate, runs through California and is one of the most famous plate boundaries. Since it is so close to home, it is no surprise that Hollywood produced an action blockbuster by the same name. A large earthquake here would cause significant damage.
But again, it is the less affluent parts of the world that are the most vulnerable to earthquake damage. Quake-prone cities like Los Angeles and Tokyo employ the latest architectural advances to make their buildings quake-resistant and protect their residents. But not all the countries along the "Pacific ring of fire" – where 81% of the world's largest earthquakes occur – can do so.
According to the 2015 Natural Hazards Risk Atlas compiled by risk analysts Verisk Maplecroft, eight of the world's ten most vulnerable cities to natural disaster are in the Philippines – which lies not only on the ring of fire but within a typhoon belt.
The harsh landscape of the Danakil Depression (Credit: AGF Srl/Alamy)
The harsh landscape of the Danakil Depression (Credit: AGF Srl/Alamy)
Fire
On the flip side of the tectonic coin is volcanic activity. Where plates move away from each other, hot magma from the beneath the Earth's surface spews up to fill the gap.
More than 200,000 people have died as a direct result of volcanoes in the last 400 years
Often described as "the cruellest place on Earth", the Danakil Depression in Ethiopia is the meeting point of three plates. It has possibly the most volcanic activity in the world.
The average annual temperature here is reportedly 34.4C, making it one of the hottest places on Earth. With low rainfall and a landscape dotted by volcanic ruptures, hydrothermal fields and salt pans, you would be forgiven for thinking nobody could survive here. But the Afar people call this place home.
In fact, humans have a habit of settling near unsettling geographic features, and that includes exploding mountains that spew out rivers of fire. The most famous example is Pompeii, the ancient Italian city buried by lava from the eruption of Mount Vesuvius. But several modern cities have views of active volcanoes. Naples is less than 6 miles from Mount Vesuvius, and Mexico City is 43 miles from Popocatépetl.
According to research published by the Global Volcano Model network in 2015, more than 200,000 people have died as a direct result of volcanoes in the last 400 years.  The international team of experts also listed the places most at risk of volcanic activity. Indonesia was at the top.
Indonesia's Mount Merapi erupted violently in 2010 (Credit: Reuters/Alamy)
Indonesia's Mount Merapi erupted violently in 2010 (Credit: Reuters/Alamy)
Mount Tambora on the island of Sumbawa directly killed 70,000 people in 1815, leading to a "year without summer" across the northern hemisphere. The eruption temporarily altered the climate, meaning the volcano ultimately claimed even more victims through famine and disease.
Naples is less than 6 miles from Mount Vesuvius, and Mexico City is 43 miles from Popocatépetl
More recently, Mount Merapi caused devastation in 2010, killing over 350 people with its explosions and suffocating ash clouds. Yet tens of thousands of lives were saved by timely evacuations.
It may not be molten lava so much as heat that represents a significant threat in the future. Across Europe in 2003, there were 70,000 deaths as a result of heat stress when a heatwave struck and temperatures soared. Urban areas are particularly at risk, so as our cities grow, heat waves could become natural nemeses for a greater proportion of humanity than ever before.
Experts in disaster mitigation will do their best to keep us safe. But it could be our own success, in procreation and economic development, that causes us the most problems.
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