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Today we wrap up the first half of our series on physical geography by taking a closer look at natural hazards - which are physical processes like heat waves and cyclones, earthquakes and volcanic eruptions, and floods and droughts. And when these natural events cause significant harm to humans, we call them natural disasters. So today we'll explore the ways geographers analyze and track these events, and take a closer look at the human impact of Hurricane Katrina in New Orleans and The Boxing Day Tsunami on the Andaman and Nicobar islands.

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#CrashCourse #Geography #NaturalHazards

We’ve visited a lot of wondrous places here on Crash Course Geography.

So as we wrap up the physical geography half of our series, let’s play a little game -- if you could pick anywhere, where would you live? Not where would you visit, but where would you live.

Like we’ve learned on our virtual Earth tour, no matter where we are, we’re embedded in a natural landscape. And that comes with opportunities -- and risks. Like if I was looking for my dream home in the US, I’d have lots of climate and topography choices because the US is big and spans multiple latitudes.

But its western rim is on the edge of the tectonic plate collision zone called the Pacific Ring of Fire. Which means the Pacific coast sees lots of earthquakes and volcanoes and even tsunamis. And hurricanes periodically batter the East coast and Gulf of Mexico along with storm surges, coastal flooding, and wind damage.

The middle’s not any safer -- lots of interior states are within what’s known as “Tornado. Alley” And pretty much all states deal with droughts, flooding, or blizzards. Not to mention heat waves in India, wildfires in Australia and Canada, and landslides in Japan.

Plus so many other natural hazards, which are extreme natural events that pose a threat to human systems and people. So we have to wonder if there’s any place on Earth safe from disaster. I’m Alizé Carrère, and this is Crash Course Geography.  INTRO.

 Natural Hazards (1:17)

Natural events are all the ways our restless Earth is constantly reshaping and modifying itself. Like volcanoes erupting or tropical cyclones...cycloning.

And so far in this course, we’ve studied why these natural events happen. Like how it’s really tectonic plates colliding and diverging that create the pattern of volcanoes along the Pacific Ring of Fire and many of those eruptions. But to be geo-literate people and fully understand what turns a natural event into a natural hazard, we have to remember that the world works as a set of physical, biological and social systems.

So we also need to study things like how humans settle the land, and how patterns of affluence, economics, and politics contribute to disasters -- the human geography stuff. In fact, every natural hazard has two main components: the actual physical event or process and the potential impact on humans.

The physical events are driven by all the physical processes we’ve learned about.  They could be meteorological events like heat waves and cyclones, geological events like earthquakes and volcanic eruptions, and hydrological events like floods, droughts, mudslides.

It’s the second component -- the impact on humans -- that changes a natural event into a natural hazard. Like severe flooding out where no one lives -- like in parts of Siberia -- is a much less severe threat to humans, so less of a hazard than a mild flood in a densely packed city -- like Jakarta.

But it’s also important to clarify what a natural hazard is not. Something that’s human-caused, like pollution events like radioactive waste or oil spills, are considered human-made disasters and are normally excluded. And when the natural event actually happens and causes significant harm to humans, we call that a natural disaster.

 Evaluating a Natural Hazard (2:49)

As geographers, we want to compare different places and answer “why would this hazard happen here and not there?” So in order to evaluate a hazard, geographers might look at several different dimensions. Like we might want to know how big the event was in some way. The height of a flood or the intensity of a windstorm measures the magnitude of the event.

Time is also an important dimension to a hazard in many ways. We might want to know about the frequency of occurrence, like if flooding is seasonal or rare and whether it occurs at a regular interval or is random, and how long it lasts or the duration of the event. And a drought might be weeks or months in the making whereas a hurricane or blizzard can appear suddenly, so we can also look at the speed of onset.

Of course, as geographers we’re always thinking about space. So we can track the areal extent over the Earth’s surface -- like how big an area was affected by an earthquake -- and the degree of spatial concentration within that area -- like the most severely affected area would be at the epicenter where there were the strongest shocks. Evaluating hazards can also tell us how they’ve changed over time and show how the environmental and human components have become even more tightly intertwined.

 New Orleans: Vulnerability (3:50)

As the human population has grown, we’ve tended to move into areas that are very attractive but also pose a high level of environmental danger -- like many cities are located in coastal areas. Or there could be other advantages, like rich volcanic soils that enable banana plantations. Our choices and social systems are increasing the impact of natural events and making some people and places more vulnerable to certain types of hazards than others.

Where we can find opportunities or what we can afford money wise has a big influence on what we’re willing to accept risk wise. Like in the American south, about half of New Orleans currently sits below sea level and people with low incomes live in the lowest-lying areas making them more vulnerable to flooding. And when in 2005 hurricane Katrina inundated 80% of the city and the flood waters rose up to 6.1 meters, these people were hit hardest by disaster preparedness and response problems.

But a poor response during a single disaster isn’t the whole story. The tax base in New Orleans was eroded because of white flight in the 1950s, 60s, and 70s, when white people -- who were usually better-off financially or were able to participate in banking and real estate markets -- relocated en masse from the central city to the suburbs. The people left had altogether less money that could be taxed.  So over time there wasn’t enough investment in the city’s drainage infrastructure.

Because of more situations like Hurricane Katrina, many geographers now think that phrases like natural disaster or natural hazard are misleading. And there’s a push to define it as “a complex web of interactions among peoples, environments and technologies, characterized by multiple causes and consequences.” Which also means there’s a lot that affects how vulnerable people are in a place.

Like it’s generally understood that wealth, education, a high degree of social organization, and advanced technology reduce vulnerability. As New Orleans rebuilt, a lot of energy and money was focused on strengthening levees, flood walls, floodgates and pumping stations to reduce vulnerability to future hurricanes. But as geographers we want to know if that’s true everywhere.

 Boxing Day Tsunami: Local Knowledge (5:41)

The Boxing Day tsunami of 2004 along the northwest coast of what’s now the Indonesian island of Sumatra was one of the most cataclysmic natural events of modern times. Its tremendous force and scope killed more than 230,000 people in 14 countries.

But in the Andaman and Nicobar Islands, a group of islands off of the southeast coast of India, the Onge, a tribe of about 100 people, survived by taking shelter on higher ground deep in their forest to escape “the fury of the wave.” The Onge have lived on the island of Little Andaman for 30,000 to 50,000 years. Their oral traditions had taught them about tsunamis and their folklore spoke of a “huge shaking of ground followed by a high wall of water.” They survived by heeding their traditions, though their settlements were completely destroyed.

So as we’re assessing vulnerability and studying how to mitigate natural disasters, we have to consider all the ways different peoples relate to their environment and the value of different types of knowledge. Textbooks and classroom instruction are useful, but experience from keenly observing and living in the world is every bit as valuable. And this is why many geoliterate geographers and disaster preparedness teams spend a lot of time ‘in the field,’ talking with local residents of their communities and learning about this knowledge.

 Kathmandu: Resilience (6:49)

Assessing how vulnerable a place is or was helps us learn a lot about natural hazards, but we also have to deal with the aftermath. The idea of resilience is an important aspect of disaster risk management because it shifts the focus from vulnerability to recovery. In disaster preparedness, resilience comes in many different forms and is defined as a system’s ability to absorb shocks and disturbances -- but still maintain its current functioning and bounce back from adverse events.

For instance, traditional town planning and land use in the Kathmandu Valley has built a strong sense of community which fosters social resilience, which is when the social bonds of a community help it recover faster. In older historic towns in Nepal, traditional open spaces like paved courtyards, chowks, neighborhood squares, and larger open spaces at the edge of towns bring communities together during feasts, festivals and rituals. And during the Gorkha earthquake of 2015, the community used these spaces as evacuation sites and to provide refuge for households during and after the disaster.

And the architecture in these towns uses mixed timber and masonry construction and specifically represents the local culture and technology, but also functions as earthquake resilience. The buildings and houses are designed to absorb external forces and withstand displacement during an earthquake. But this style of architecture wouldn’t necessarily help the resilience of a city like San Francisco or Tokyo where skyscrapers and high rises are common.

Different cultures can have different attitudes about risk, the role of government, and collective social responsibility too. Usually what makes a place resilient locally or regionally is really specific, so there’s no universal solution. But resilience implies a way forward, and enhancing the resilience of cities and communities is a broad policy objective at international, national and sub-national levels.

But no matter how prepared we are, some things can never be recovered after a natural disaster. Homes and businesses can be rebuilt and belongings can be recovered, but we’ve also lost a place and our sense of and attachment to places. So there’s a serious element to our “where would you live” game.

 Summary (8:41)

Natural hazards constantly threatening our home is emotionally exhausting, but for some, there’s no other choice. How people should prepare for and respond appropriately to disaster risks involves understanding and forecasting a natural event and public perception, risk communication, what capacity there is to implement different strategies, as well as ethics and compassion. It takes an incredible amount of knowledge, time, and effort so that in the recovery phase community resilience is strengthened and its capacity to cope with the impact of future hazards grows.

Likely no place is entirely safe from natural hazards -- especially as social and environmental challenges multiply. But as we conclude the physical geography half of our series we’re hopefully better able to understand how rock structures, landforms, soils, vegetation, climate, and weather affect natural environments and our roles in them. When we think like physical geographers we’re better equipped to understand places spatially and appreciate all the connections between all the different parts of whatever landscape we’re in -- including the humans!

The physical geographers of tomorrow are studying humans as agents that sculpt and transform the landscape, and are focusing on environmental change and global warming. And I hope we can each take a piece of physical geography with us in our lives.

If I could live anywhere, I’d live somewhere on the Pacific Ring of Fire where I could see volcanoes creating new land.  Or near the floodplains of the Zambezi where the river carves into the Earth. Or right here in Miami, where tropical storms both nourish and batter the landscape, and where I can learn from and explore how people adapt and innovate in amazing ways. And where I can share it all with you and make Crash Course, right here in my living room.

Tell me in comments where our time studying physical geography has inspired you to dream about living, and I’ll see you next time as we start exploring human geography and the importance of the names and places we call home.

Many maps and borders represent modern geopolitical divisions that have often been decided without the consultation, permission, or recognition of the land's original inhabitants. Many geographical place names also don't reflect the Indigenous or Aboriginal peoples languages.

So we at Crash Course want to acknowledge these peoples’ traditional and ongoing relationship with that land and all the physical and human geographical elements of it. We encourage you to learn about the history of the place you call home through resources like and by engaging with your local Indigenous and Aboriginal nations through the websites and resources they provide. Thanks for watching this episode of Crash Course Geography which is filmed at the Team.

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