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Welcome to the Natural disasters Teens 11 Wiki!

This is an academic wiki which aims to explain how natural disasters happen and their consequences in human life.

Avalanche Edit

An avalanche (also called a snowslide) is an event that occurs when a cohesive slab of snow lying upon a weaker layer of snow fractures and slides down a steep slope. Avalanches are typically triggered in a starting zone from a mechanical failure in the snowpack (slab avalanche) when the forces of the snow exceed its strength but sometimes only with gradual widening (loose snow avalanche). After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. If the avalanche moves fast enough, some of the snow may mix with the air forming a powder snow avalanche, which is a type of gravity current.

Slides of rocks or debris, behaving in a similar way to snow, are also referred to as avalanches (see rockslide). The remainder of this article refers to snow avalanches.

The load on the snowpack may be only due to gravity, in which case failure may result either from weakening in the snowpack or increased load due to precipitation. Avalanches initiated by this process are known as spontaneous avalanches. Avalanches can also be triggered by other loading conditions such as human or biologically related activities. Seismic activity may also trigger the failure in the snowpack and avalanches.

Although primarily composed of flowing snow and air, large avalanches have the capability to entrain ice, rocks, trees, and other surficial material. However, they are distinct from slushflows which have higher water content and more laminar flow, mudslides which have greater fluidity, rock slides which are often ice free, and serac collapses during an icefall. Avalanches are not rare or random events and are endemic to any mountain range that accumulates a standing snowpack. Avalanches are most common during winter or spring but glacier movements may cause ice and snow avalanches at any time of year. In mountainous terrain, avalanches are among the most serious objective natural hazards to life and property, with their destructive capability resulting from their potential to carry enormous masses of snow at high speeds.

There is no universally accepted classification system for different forms of avalanches. Avalanches can be described by their size, their destructive potential, their initiation mechanism, their composition and their dynamics.

Most avalanches occur spontaneously during storms under increased load due to snowfall and/or erosion. The second largest cause of natural avalanches is metamorphic changes in the snowpack such as melting due to solar radiation. Other natural causes include rain, earthquakes, rockfall and icefall. Artificial triggers of avalanches include skiers, snowmobiles, and controlled explosive work. Contrary to popular belief, avalanches are not triggered by loud sound; the pressure from sound is orders of magnitude too small to trigger an avalanche.

Avalanche initiation can start at a point with only a small amount of snow moving initially; this is typical of wet snow avalanches or avalanches in dry unconsolidated snow. However, if the snow has sintered into a stiff slab overlying a weak layer then fractures can propagate very rapidly, so that a large volume of snow, that may be thousands of cubic meters, can start moving almost simultaneously.

A snowpack will fail when the load exceeds the strength. The load is straightforward; it is the weight of the snow. However, the strength of the snowpack is much more difficult to determine and is extremely heterogeneous. It varies in detail with properties of the snow grains, size, density, morphology, temperature, water content; and the properties of the bonds between the grains. [3] These properties may all metamorphose in time according to the local humidity, water vapour flux, temperature and heat flux. The top of the snowpack is also extensively influenced by incoming radiation and the local air flow. One of the aims of avalanche research is to develop and validate computer models that can describe the evolution of the seasonal snowpack over time.[4] A complicating factor is the complex interaction of terrain and weather, which causes significant spatial and temporal variability of the depths, crystal forms, and layering of the seasonal snowpack.

Slab avalanches Edit

Slab avalanches form frequently in snow that has been deposited, or redeposited by wind. They have the characteristic appearance of a block (slab) of snow cut out from its surroundings by fractures. Elements of slab avalanches include the following: a crown fracture at the top of the start zone, flank fractures on the sides of the start zones, and a fracture at the bottom called the stauchwall. The crown and flank fractures are vertical walls in the snow delineating the snow that was entrained in the avalanche from the snow that remained on the slope. Slabs can vary in thickness from a few centimetres to three metres. Slab avalanches account for around 90% of avalanche-related fatalities in backcountry users.

Powder snow avalanches Edit

The largest avalanches form turbulent suspension currents known as powder snow avalanches or mixed avalanches. These consist of a powder cloud, which overlies a dense avalanche. They can form from any type of snow or initiation mechanism, but usually occur with fresh dry powder. They can exceed speeds of 300 kilometres per hour (190 mph), and masses of 10000000 tonnes; their flows can travel long distances along flat valley bottoms and even uphill for short distances.

Wet snow avalanches Edit

In contrast to powder snow avalanches, wet snow avalanches are a low velocity suspension of snow and water, with the flow confined to the track surface (McClung, first edition 1999, page 108). The low speed of travel is due to the friction between the sliding surface of the track and the water saturated flow. Despite the low speed of travel (~10–40 km/h), wet snow avalanches are capable of generating powerful destructive forces, due to the large mass and density. The body of the flow of a wet snow avalanche can plough through soft snow, and can scour boulders, earth, trees, and other vegetation; leaving exposed and often scored ground in the avalanche track. Wet snow avalanches can be initiated from either loose snow releases, or slab releases, and only occur in snow packs that are water saturated and isothermally equilibrated to the melting point of water. The isothermal characteristic of wet snow avalanches has led to the secondary term of isothermal slides found in the literature (for example in Daffern, 1999, page 93). At temperate latitudes wet snow avalanches are frequently associated with climatic avalanche cycles at the end of the winter season, when there is significant daytime warming.

Death cause by avalanche Edit

People caught in avalanches can die from suffocation, trauma, or hypothermia. On average, 28 people die in avalanches every winter in the United States.[8]. Globally, an average of over 150 people die each year from avalanches.

Ice avalanche Edit

An ice avalanche occurs when a large piece of ice, such as from a serac or calving glacier, falls onto ice (such as the Khumbu Icefall), triggering a movement of broken ice chunks. The resulting movement is more analogous to a rockfall or a landslide than a snow avalanche. They are typically very difficult to predict and almost impossible to mitigate.

Prevention Edit

Preventative measures are employed in areas where avalanches pose a significant threat to people, such as ski resorts, mountain towns, roads, and railways. There are several ways to prevent avalanches and lessen their power and develop preventative measures to reduce the likelihood and size of avalanches by disrupting the structure of the snowpack, while passive measures reinforce and stabilize the snowpack in situ. The simplest active measure is repeatedly traveling on a snowpack as snow accumulates; this can be by means of boot-packing, ski-cutting, or machine grooming. Explosives are used extensively to prevent avalanches, by triggering smaller avalanches that break down instabilities in the snowpack, and removing overburden that can result in larger avalanches. Explosive charges are delivered by a number of methods including hand-tossed charges, helicopter-dropped bombs, Gazex concussion lines, and ballistic projectiles launched by air cannons and artillery. Passive preventive systems such as snow fences and light walls can be used to direct the placement of snow. Snow builds up around the fence, especially the side that faces the prevailing winds. Downwind of the fence, snow buildup is lessened. This is caused by the loss of snow at the fence that would have been deposited and the pickup of the snow that is already there by the wind, which was depleted of snow at the fence. When there is a sufficient density of trees, they can greatly reduce the strength of avalanches. They hold snow in place and when there is an avalanche, the impact of the snow against the trees slows it down. Trees can either be planted or they can be conserved, such as in the building of a ski resort, to reduce the strength of avalanches.

In turn, socio-environmental changes can influence the occurrence of damaging avalanches: some studies linking changes in land-use/land-cover patterns and the evolution of snow avalanche damage in mid latitude mountains show the importance of the role played by vegetation cover, that is at the root of the increase of damage when the protective forest is deforested (because of demographic growth, intensive grazing and industrial or legal causes), and at the root of the decrease of damage because of the transformation of a traditional land-management system based on overexploitation into a system based on land marginalization and reforestation, something that has happened mainly since the mid-20th century in mountain environments of developed countries.

What Causes Avalanches?

Avalanches occur due to any of the following triggers: overloading, temperature, slope angle, snow pack conditions, and vibration. Overloading is an important trigger, the weight of the snow increases until it overcomes cohesion to the snow pack underneath. Temperature has an effect on the cohesion of snow; a rise in temperature weakens the bonds creating weakness, whilst a fall in temperature increases the brittleness and tension of a slab. Slope angle is important as most avalanches occur on slopes between 25 and 400C, although avalanches have been noted on slopes as gentle as 150C and as steep as 60oC. Snow pack conditions is a significant factor as the layers below the upper snow can not be seen and it is difficult to assess whether the slope is likely to fail. Vibration is a physical trigger cause by thunder, a gun shot, by explosions or other loud noises such as shouting. Earthquakes can start avalanches, as well as noise from heavy machinery.

Where can avalanches occur?

Mountainous areas throughout arctic and temperate regions which have slope angles between 25oC and 60oC are at risk. However, other conditions may affect the likelihood of an avalanche being triggered as already mentioned. The avalanche problem is more severe in Europe than North America due to the higher population densities in the Alp mountain range.

History of recent avalanches Edit

Cascade range, Washington (1910) The Cascade Range, Washington is the worst avalanche disaster in the USA to date. Three snow-bound trains were swept into a canyon which killed 118 people. Montroc, France (1999) This avalanche occurred when 300,000 cubic metres of snow slid down a 30 degree slope which reached a speed of 60 miles an hour. Chalets were covered in 100,000 tons of snow, killing 12 people. Alps (World war I)

During World War I approximately 50,000 soliders died due to avalanches at the Austrian-Italian front in the Alps. It is thought the avalanches were caused by the artillery fire.

Disease Edit

800px-Mycobacterium tuberculosis

What is it? Edit

A disease is a particular abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any immediate external injury. Diseases are often known to medical conditions that are associated with specific symptoms and signs. A disease may be caused by external factors such as pathogens or by interna

l dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergies and autoimmune disorders.

What causes it? Edit

Death due to disease is called death by natural causes. There are four main types of disease: infectious diseases, deficiency diseases, hereditary diseases (including both genetic diseases and non-genetic hereditary diseases), and physiological diseases. Diseases can also be classified in other ways, such as communicable versus non-communicable diseases. The deadliest diseases in humans are coronary artery disease (blood flow obstruction), followed by cerebrovascular disease and lower respiratory infections. In developed countries, the diseases that cause the most sickness overall are neuropsychiatric conditions, such as depression and anxiety.

Only some diseases such as influenza are contagious and commonly believed infectious. The micro-organisms that cause these diseases are known as pathogens and include varieties of bacteria, viruses, protozoa and fungi. Infectious diseases can be transmitted, e.g. by hand-to-mouth contact with infectious material on surfaces, by bites of insects or other carriers of the disease, and from contaminated water or food (often via fecal contamination), etc. Also, there are sexually transmitted diseases. In some cases, microorganisms that are not readily spread from person to person play a role, while other diseases can be prevented or ameliorated with appropriate nutrition or other lifestyle changes.

Some diseases, such as most (but not all) forms of cancer, heart disease, and mental disorders, are non-infectious diseases. Many non-infectious diseases have a partly or completely genetic basis (see genetic disorder) and may thus be transmitted from one generation to another.

Social determinants of health are the social conditions in which people live that determine their health. Illnesses are generally related to social, economic, political, and environmental circumstances. Social determinants of health have been recognized by several health organizations such as the Public Health Agency of Canada and the World Health Organization to greatly influence collective and personal well-being. The World Health Organization's Social Determinants Council also recognizes Social determinants of health in poverty.

When the cause of a disease is poorly understood, societies tend to mythologize the disease or use it as a metaphor or symbol of whatever that culture considers evil. For example, until the bacterial cause of tuberculosis was discovered in 1882, experts variously ascribed the disease to heredity, a sedentary lifestyle, depressed mood, and overindulgence in sex, rich food, or alcohol—all the social ills of the time.

When a disease is caused by a pathogen (e.g., when the disease malaria is caused by infection by plasmodium parasites.), the term disease may be misleadingly used even in the scientific literature in place of its causal agent, the pathogen. This language habit can cause confusion in the communication of the cause-effect principle in epidemiology, and as such it should be strongly discouraged.

It can be caused by:

Airborne
An airborne disease is any disease that is caused by pathogens and transmitted through the air.
Foodborne
Foodborne illness or food poisoning is any illness resulting from the consumption of food contaminated with pathogenic bacteria, toxins, viruses, prions or parasites.
Infectious
Infectious diseases, also known as transmissible diseases or communicable diseases, comprise clinically evident illness (i.e., characteristic medical signs or symptoms of disease) resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism. Included in this category are contagious disease—an infection, such as influenza or the common cold, that commonly spreads from one person to another—and communicable disease—a disease that can spread from one person to another, but does not necessarily spread through everyday contact.
Lifestyle
A lifestyle disease is any disease that appears to increase in frequency as countries become more industrialized and people live longer, especially if the risk factors include behavioral choices like a sedentary lifestyle or a diet high in unhealthful foods such as refined carbohydrates, trans fats, or alcoholic beverages.
Non-communicable
A non-communicable disease is a medical condition or disease that is non-transmissible. Non-communicable diseases cannot be spread directly from one person to another. Heart disease and cancer are examples of non-communicable diseases in humans.

What are it consequence? Edit

In humans, disease is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases can affect people not only physically, but also mentally, as contracting and living with a disease can alter the affected person's perspective on life.

How to prevent? Edit

Decrease your risk of infecting yourself or others:

  • Wash your hands often. This is especially important before and after preparing food, before eating and after using the toilet.
  • Get vaccinated. Immunization can drastically reduce your chances of contracting many diseases. Keep your recommended vaccinations up-to-date.
  • Use antibiotics sensibly. Take antibiotics only when prescribed. Unless otherwise directed, or unless you are allergic to them, take all prescribed doses of your antibiotic, even if you begin to feel better before you have completed the medication.
  • Stay at home if you have signs and symptoms of an infection. Don't go to work or class if you're vomiting, have diarrhea or are running a fever.
  • Be smart about food preparation. Keep counters and other kitchen surfaces clean when preparing meals. In addition, promptly refrigerate leftovers. Don't let cooked foods remain at room temperature for an extended period of time.
  • Disinfect the 'hot zones' in your residence. These include the kitchen and bathroom — two rooms that can have a high concentration of bacteria and other infectious agents.
  • Practice safer sex. Use condoms. Get tested for sexually transmitted diseases (STDs), and have your partner get tested— or, abstain altogether.
  • Don't share personal items. Use your own toothbrush, comb or razor blade. Avoid sharing drinking glasses or dining utensils.
  • Travel wisely. Don't fly when you're ill. With so many people confined to such a small area, you may infect other passengers in the plane. And your trip won't be comfortable, either. Depending on where your travels take you, talk to your doctor about any special immunizations you may need.

With a little common sense and the proper precautions, you can avoid infectious diseases and avoid spreading them.

Complications Edit

Most infectious diseases have only minor complications. But some infections — such as pneumonia, AIDS and meningitis — can become life-threatening. A few types of infections have been linked to a long-term increased risk of cancer:

  • Human papillomavirus is linked to cervical cancer
  • Helicobacter pylori is linked to stomach cancer and peptic ulcers
  • Hepatitis B and C have been linked to liver cancer

In addition, some infectious diseases may become silent, only to appear again in the future — sometimes even decades later. For example, someone who's had chickenpox may develop shingles much later in life.

4 reasons disease outbreaks are erupting around the world Edit

1. More travel, trade, and connectivity Edit

For most of history, humans lived in small, disparate bands that were relatively isolated from each other. "Only comparatively recently has there been extensive contact between peoples, flora and fauna from both old and new worlds," write researchers in a paper on global transport and infectious disease spread.

The rise of sailing in the 1300s helped spread deadly plague around the world through rat populations carried on boats.

And then the slave trade of the 16th and 17th centuries introduced Aedes aegypti — the mosquito type that today spreads viruses like Zika, yellow fever, and dengue — to the Americas from West Africa.

These pathogens spread at a relatively slow pace. It took more than 10 years for plague to spread across Europe, for example.

Air travel changed all that. "The jet plane took off in the '70s and accelerated during the '80s and '90s," said Duane Gubler, an infectious diseases specialist and former director of the division of vector-borne disease at the Centers for Disease Control and Prevention. "So now we have this modern transportation or globalization that is moving animals, humans, commodities, and pathogens around the world."

The movement of people and goods is happening at a faster rate and greater volume than at any other time.

You can now travel pretty much anywhere in the world in a day. And unlike the plague lurching across Europe in the 1300s, a traveler can now bring a deadly strain of bird flu from China to Europe within 24 hours.

When a pathogen is introduced to a new place, people are biologically more susceptible to the disease, since their immune systems have probably never been exposed and have no experience fending it off. Doctors and health systems can also be caught off guard.

This is one of the factors that helped the recent Ebola epidemic in West Africa spiral out of control: the three most affected countries had never experienced an outbreak of the virus before.

"Clinicians had never managed cases," the World Health Organization reported. "No laboratory had ever diagnosed a patient specimen. No government had ever witnessed the social and economic upheaval that can accompany an outbreak of this disease. Populations could not understand what hit them or why."

Contrast that with East Africa, which has had plenty of experience dealing with Ebola outbreaks over several decades. In Uganda, for example, as soon as an Ebola case is identified, public health officials overwhelm all streams of media with messages about how to stay safe. People won't leave their houses out of fear of infection, and they immediately report suspected cases to surveillance officials. It's one of the reasons Uganda has successfully stamped out about half a dozen Ebola outbreaks.

This new context helped spread an old virus around quickly, leading to more than 15,000 cases and 11,000 deaths.

2. Urbanization-"an emerging humanitarian disasters" Edit

Not only are people and goods traveling farther and at a greater volume and speed than any other time in history, but people are also more likely to live in densely populated urban environments.

More than half of the world's population now lives in cities, and just about every country on the planet is becoming more urbanized. Global health researchers have called the trend "an emerging humanitarian disaster."

That's because most people don't live in relatively clean cities like Washington, DC, or Munich. "Most cities are unplanned, and many people — tens of millions — now live in crowded, unhygienic conditions," said Gubler.

Cities can be perfect breeding grounds for disease to spread. Consider the ongoing Zika outbreak in Brazil. Not only was this an old virus in a new country that caught health officials off guard but Brazil's many cities also happened to be extremely hospitable to the virus.

The Aedes aegypti mosquito, which carries Zika, thrives alongside people. As Gubler wrote in this 2011 paper, "[It's] a highly domesticated urban mosquito that prefers to live with humans in their homes, feed on humans and lay eggs in artificial containers made by humans." (Think tires or plastic cups.)

Across Latin America, 113 million people (nearly one in five) live in slums. Many of these slums lack a clean and steady water supply, so people keep buckets filled with water around their homes — ideal mosquito breeding grounds. Not to mention the fact that air conditioning isn't common, leaving bodies and homes warm and making them even more hospitable to the disease-carrying bugs.

Globally, unprecedented population growth following World War II has meant that not only are more people living in cities than ever before but populations are also exploding into areas that were once inhabited only by other animals.

Anytime humans interact with animals, there's a chance that a pathogen could make the leap across species and sicken them. Today about three-quarters of new emerging infectious diseases are spread to humans by animals — a health threat that came with the rise of agriculture.

As the historian Yuval Harari writes in his sweeping history of humankind, Sapiens: "Most of the infectious diseases that have plagued agricultural and industrial societies (such as small pox, measles, and tuberculosis) originated in domesticated animals and were transferred to humans only after the Agricultural Revolution."

Today, this is still the case, whether it's chicken sellers sitting on the streets of China risking exposure to bird flu or hunters in Guinea eating bushmeat that could be infected with the Ebola virus.

"That’s why many of these infections come out of Africa or Asia, where there's a strong link between humans, animals, and the environment," said Ali Khan, author of The Next Pandemic and the former director of the Office of Public Health Preparedness and Response at the CDC.

3. Pervasive poverty means outbreak will be worse. Edit

When new viruses strike impoverished or weakened health systems, they have a much greater chance of thriving and killing people.

The 2014-'15 Ebola epidemic offers another illustrative example here. Every American infected with Ebola during that period survived. The same wasn't true for the affected West Africans, 11,000 of whom died.

The stark difference in outcomes had to do with money and access to health care: Patients with Ebola can be kept alive through tried-and-true health measures — kidney dialysis, IV rehydration, antibiotics — and 24-hour hospital care. While that's possible at the National Institutes of Health in Bethesda, Maryland, it wasn't in many of the places where Ebola struck, like Gueckedou, Guinea.

We're seeing a similar story play out right now with an outbreak of yellow fever in Angola. More than 2,500 people have been infected with the virus, and 300 have died, in an ongoing outbreak.

This outbreak could have been prevented. While there's no cure for yellow fever, a vaccine was developed in 1936, and it's highly effective. Within three or four weeks after receiving the shot, nearly all people are protected from the virus. But in order for the vaccine to really prevent outbreaks, many people need to be immunized.

That's not happening in many parts of Africa, including Angola, where the virus is endemic. Starting in 2006, the World Health Organization, with support from Gavi (an international organization focused on improving vaccine access), ramped up efforts to make sure at-risk communities got vaccinated. But many countries on the continent still have vaccine coverage rates that are much too low to make the vaccine effective.

So because of poverty and weak health systems, even when we have the technology to stop disease spread, we don't get to use it.

"Politics and social factors play a determining role in whether or not you have one or two cases — and whether or not you have an outbreak or pandemic," said Khan. "We probably can't prevent the one to two cases. But we sure as heck can prevent the pandemic."

4. A warning climate is helping fuel more disease outbreaks Edit

When we think about health, experts say, we need to start thinking about how environmental factors like climate change can matter as much as — or sometimes even more than — our personal behaviors.

In a report released in June 2015, The Lancet brought together the world’s leading experts on environmental health. They argue that "[t]he implications of climate change for a global population of 9 billion people threatens to undermine the last half century of gains in development and global health," including the spread of disease vectors.

For example, Zika, dengue, and chikungunya are all spread by the Aedes mosquito. And one of the reasons researchers think Aedes may be reaching new places —and more people — lately is climate change. (Mosquitoes thrive in warm and moist environments.)

Bird flu, cholera, Lyme disease — researchers believe all are being made worse by climate change.

In his decades as a disease detective for the CDC, Khan has witnessed the expansion of vector-borne diseases in the US. "It’s already happening now," he said. "And it's only going to continue to accelerate as our climate continues to get warmer, as we continue to have these extremes in rain fall, and weather events."

Despite all this, we're getting better at stopping outbreaks Edit

The researchers who published on the rise of infectious disease outbreaks in The Royal Society also found that while the number of outbreaks was increasing globally, the number of outbreak cases per capita was actually declining over time: "Our data suggest that, despite an increase in overall outbreaks, global improvements in prevention, early detection, control and treatment are becoming more effective at reducing the number of people infected."

The researchers I spoke to also mentioned that we've generally gotten better at detecting outbreaks and advancing medical technologies — vaccines, medicines, diagnostics — needed to control spread.

Where we fail, they all said, was in strengthening public health systems globally to reduce the risk of a couple of cases turning into something much bigger and deadlier.

For example, the vector control programs that started after the WWII, Gubler pointed out, have been victims of their own success.

"Health authorities couldn't see any sense in continuing to spend a lot of money to control diseases that weren't occurring, so the programs were disbanded," he explained. "At the same time, many countries disbanded their public health infrastructure to deal with vector-borne diseases." This is another reason mosquito-borne diseases like yellow fever, dengue, and Zika are on the rise.

The money spent on public health has been in a steady free fall in the US in recent years. When health emergencies like Zika or Ebola hit, there's no emergency funding mechanism to quickly get a response in place. And at the global level, the budget of the World Health Organization has been at a standstill and not adjusted for inflation for years.

Yet what stopped the SARS and Ebola outbreaks from truly going global were simple, old-fashioned public health measures like contact tracing and quarantines.

"We continue to invest in the latest technology or gadget in order to prolong our lives by a few more days — stem cell therapies, personalized medicine — when a lot of our health depends on public health," said global health professor (and Vox contributor) Steven Hoffman.

Investing in public health means having strong disease surveillance systems and lab networks in place, public health officials ready to coordinate emergency health responses, and research capacity to quickly develop outbreak countermeasures like medicines and vaccines.

We're long overdue for a catastrophic flu pandemic, Hoffman added. "Our luck will run out. But in the meantime we need to ensure limited resources are allocated effectively."

Earthquake Edit

It is a shake of the ground produced by forces acting inside the planet. The word earthquake comes from the Latin terraemotus, while earthquake derives from a Greek word that means, precisely, "shake."


The earthquake occurs with the collision of tectonic plates, which are fragments of the lithosphere (the most superficial layer of the Earth) that move like a rigid block, without an internal deformation on the asthenosphere (the layer immediately to the lithosphere, which is between about 100 and about 240 kilometers below the surface).

Another cause of earthquakes is the reorganization of the components of the earth's crust that releases a large amount of energy, whether by volcanic processes, hillside movements or the potential elastic energy that accumulates with the gradual deformation of the rocks found next to an active fault.

The inner point of the planet where the earthquake takes place is known as seismic focus or hypocenter. On the other hand, the point of the surface that is in the vertical of the hypocenter (that is, it is located perpendicular to it) is called the epicenter.

Seismic movements propagate through elastic waves from the hypocenter. There are three major types of seismic waves: the primary, longitudinal or P waves (they propagate in the same direction as the vibration of the particles); secondary, transverse or S waves (propagate perpendicular to the sense of vibration of the particles); and surface waves (occur on the earth's surface as a result of the interaction between primary and secondary waves).

===
The most violent earthquakes in history === This catastrophe does not contemplate social classes nor does it notify well in advance when it will take place; such is that its consequences can be many times atrocious, devastating regions and entire countries, with the consequent deaths of its inhabitants.

Throughout the history of mankind there have been countless earthquakes, among the strongest are the following:

Japan earthquake of March 2011: it is undoubtedly the strongest in history and reached 8.9 degrees on the Richter scale.

An earthquake happens when, suddenly, two tectonic plates slide over each other. The surface on which they slide is called the fault or the plane of the fault. The place below the earth's surface where the earthquake occurs is known as the hypocenter, and its direct location on the earth's surface is known as the epicenter.


WHAT IS AN EARTHQUAKE AND HOW IS IT FORMED Edit

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MAIN DEFINITION Edit

An earthquake happens when, suddenly, two tectonic plates slide over each other. The surface on which they slide is called the fault or the plane of the fault. The place below the earth's surface where the earthquake occurs is known as the hypocenter, and its direct location on the earth's surface is known as the epicenter.

Sometimes an earthquake is preceded by initial tremors. These are smaller earthquakes that happen in the same place where the strongest earthquake will occur.

Scientists cannot predict what will happen because of what they don't know how to warn the population. The main earthquake, the strongest, is often followed by aftershocks. These tremors tend to be smaller and occur after the main earthquake has occurred. Depending on the size of the earthquake, subsequent aftershocks may continue for weeks, months and even years.

According to their occurrence in a natural way, everything develops when the surface on which the plates slide, they overlap or collide and this is known as failure or plane of failure. On the other hand, the location from which the fault originates is the so-called hypocenter and that which is exactly above it, is the epicenter. On the surface, we perceive the earthquake as a shock that, after the collision of the plates, releases energy (seismic waves) in the course of a sudden reorganization of materials from the earth's crust, by overcoming the state of mechanical equilibrium.

Generally, the earthquake causes a great tremor in the ground that, on occasion, can continue with a series of many other minor tremors, these are called aftershocks, while the strongest is called the main earthquake. The replicas are really curious, they can continue to develop for weeks, months and even, even more than a year after the main earthquake!

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We had said that there are also other causes of an earthquake, they are: the landslides of rocks on the slopes of the mountains, the sinking of caves, the abrupt variations in atmospheric pressure by cyclones and the underground activity caused by a volcano in eruption process But it can also be caused by external forces caused by Man, being the result of nuclear experiments or the power exerted by the millions of tons of water accumulated in dams and artificial lakes, as well as mining accidents and oil excavations.

Everyone has the image of an earthquake in mind. We have seen them in the cinema and on television, where they have sneaked through fiction or on the news channels when they take place in different countries. Earthquakes are associated with soil movement, which means that everything around us trembles and, in some cases, there are great devastation and personal injury.

However, what exactly are earthquakes? How many types exist and what do they imply? If you want to discover it, keep reading a HOWTO and we will tell you in this article about Earthquakes: what they are, types, causes and consequences.

Causes of earthquakes Edit

The causes of earthquakes can be of two types: natural or artificial

Natural causes of earthquakes Edit

They are the consequence of the activity of plate tectonics of the planet itself. The planet Earth is composed of a solid core, which is followed by a next layer called a mantle and that is liquid. This layer is mainly composed of magma which, being liquid, is in motion. Finally, there is the final layer, the crust, composed of various plates called tectonic plates that float on that liquid mantle. When the activity of the mantle moves the tectonic plates that make up the surface, the earth shakes, which causes natural earthquakes. As it can not be otherwise, the areas where the faults are found (that is, the separations between the tectonic plates), register greater seismic activity because the movements of the mantle cause these plates to collide with each other.

Artificial causes of earthquakes Edit

They are the consequence of human activity. In these cases, the earthquakes do not come from the inner activity of the planet, but are a consequence of human actions that can cause the earth to tremble the same as it does when earthquakes occur naturally. An example of this type of earthquakes would be found during the detonation of an atomic bomb, which in addition to the devastation caused by the bomb itself and the resulting radiation, would also imply an earthquake that could clearly be described as an earthquake.

Types of earthquakes Edit

One of the ways of cataloging earthquakes would be according to their nature (natural or artificial), as we have seen. However, the most common is that the typology of earthquakes is associated with the energy released. That is, the force with which they shake the earth and that, consequently, is directly associated with its destructive power.

One of the most common ways of cataloging earthquake types is through the Richter scale. This scale establishes the strength of earthquakes from 0 to 10 force points, establishing up to 8 types of possible earthquakes. These are the different types of earthquakes that exist:

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Earthquakes of less than 2 points: they are called microsisms, barely noticeable.

Earthquakes from 2 to 3.9 points: they are called minor earthquakes, since they rarely cause damage.

Earthquakes with 4 to 4.9 points: these are called light earthquakes; cause little damage that is usually limited to the movement of objects in the rooms.

Earthquakes with 5 to 5.9 points: these types of earthquakes are called moderate, since they can cause damage to weak structures.

Earthquakes from 6 to 6.9 points: they are the forts and, in this case, they are earthquakes that can destroy populated areas and buildings.

Earthquakes from 7 to 7.9 points: these are major earthquakes, causing serious damage in populated areas.

Earthquakes from 8 to 9.9 points: this type of earthquakes are called cataclysms, since they are the most devastating that are known and can cause damage in areas of hundreds of kilometers.

Earthquakes with more than 10 points: they are called legendary or apocalyptic earthquakes, none of them have ever been recorded.

For more information on this system, check out this article on the Difference between the Richter and Mercalli scales.

One of the natural phenomena that has wreaked havoc ever since humanity has a memory, but that has also shaped the world, without a doubt they have been earthquakes, because their impact is very extensive and due to their origins, they are surely even the same of old people than the same land.


People have always tried to understand these events, since in the past they were considered as divine were to be appeased. Nowadays, with the use of technology, it is possible to know what causes them, which shows us the incredible strength of nature, since it is not something that can be avoided. Despite this, one can be aware of its effects on society to serve as support when such a situation arises.

Causes of earthquakes Edit

Tectonic plates Edit

After many years and great technological advances, it was discovered that the earth is formed of plates in constant motion and that the clash between them is what generates the movements on the surface that we know as earthquakes. In addition to colliding, they also move away from each other and in some sections their edges rub in opposite directions. The magnitudes in these cases vary, but it is the most recurrent way in which this situation occurs.

Volcanoes Edit

The eruption of a volcano also has a lot to do with what happens inside the planet, since what comes out of these is the molten rock under the crust, so the surface also moves during an eruption. When the magma is released normally there is usually a vacuum that is filled by other rocks, which when moving generate tremors. It is also the case that the pressure inside a volcano builds up for a long time and at the time of release it does so with a huge explosion that causes a more turbulent movement.

Consequences of earthquakes Edit

Construction damage Edit

One of the impacts that can be seen with the naked eye is the damage suffered by the buildings, since they end up cracked, some parts fall out or there is simply no trace of them. In this case, buildings or houses that are older than years and that were not built with current standards that seek to counteract telluric movements as much as possible are more vulnerable.

Tsunamis Edit

When the tremors occur in the sea or on the coast, the most immediate effect is a tsunami, since inertia causes a great movement in the water that is capable of generating large waves with great destructive power. There are those who might think that it is only about water and there is no greater danger, but the detail is in the speed at which the earth impacts and the height they reach, since there are cases in which they exceed twenty meters, so devastate everything in its path or failing, leave it completely flooded.

Human casualties Edit

One of the most serious repercussions that have, but that sometimes is inevitable by the force of the tremors. The most common cases are those of people who are trapped in buildings, because if they were not built properly they fall. Similar situations also occur on roads or bridges, but in general it is a phenomenon that puts all people at risk.

Slides Edit

In mountainous areas such situations are very common, since the movements are so strong that huge rocks or large amounts of land fall at great speed, burying everything in its path. The most vulnerable parts are the edges, which in some cases is where a road is located, so its effects become quite serious.

Economic losses Edit

Looking at it from an economic point of view, there are many effects that have a great cost. The repair of structures will require a lot of time and money, in addition to the construction of new constructions that follow appropriate earthquake regulations.

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If roads or bridges are destroyed, communication between towns or cities is cut off, which prevents products, food and people from arriving, so there is no money flow. In the damaged areas there are no conditions for businesses to sell things, since the movement could have directly affected them or there are simply no customers

What to do in case of an earthquake? Edit

For the authorities, the question of survival is prevention, not only from governments and state agencies, but from families. Entities such as the National Emergency Office of the Ministry of Interior and Public Security of Chile (Onemi), the National Civil Protection System of Mexico, the Red Cross and the United States Geological Survey (USGS) point out that it is key that people living in risk areas live in houses designed in a responsible manner and complying with earthquake regulations, that residents know first-hand contingency and evacuation plans and have a survival briefcase with documents, first aid kit, radio, flashlight , food and a whistle, explains Onemi. But the earthquakes so far cannot be predicted or avoided. So what to do during an earthquake to ensure survival? This is a compilation of the main recommendations of these organizations.

AT HOME Edit

What to do:

If one is inside a home, USGS strongly recommends staying inside and standing under a table or in a hallway against an internal wall.

The Onemi of Chile calls these types of sites a Seismic Protection Place, that is, a place away from windows and objects that may fall on them.

The recommendation is to protect yourself under or next to a firm element.

In addition, as far as possible, the electricity must be cut off and the water and gas stopcocks closed.

Use flashlights.

Does the ‘triangle of life’ serve?

This method, created by Doug Copp - rescue manager and disaster management director of American Rescue Team International (a private company not affiliated with the United States government) - indicates that during an earthquake “you have to lie down near the furniture and do not get under them ”because when“ the buildings fall, the furniture generally crushes, but there is always a triangular void next to them that is not affected (space in which the person is lying) ”, explains the Ministry of Colombia education. However, it is a concept that has been revalued by experts because "it is not scientifically proven that furniture and structural elements resist enough to form the famous triangular void," says the Colombian government. USGS indicates that it is a misconception and that based on observations of an earthquake in Turkey, that technique does not apply to buildings constructed in the United States, for example.


The American Red Cross recommends bending over, covering and grabbing a sturdy table or desk. “Crouch under a sturdy desk or table, hold on and protect your eyes by pressing your face against your arm. If there is no table or desk nearby, sit on the floor against an interior wall away from windows, shelves or tall furniture that could fall on you. ”

What NOT to do Edit

Do not use elevators. Do not light with candles, matches or lighters.

Do not shout, or run, let alone push other people, indicates the National Civil Protection System of Mexico,.

Do not run on the stairs while the building is moving or if there is a danger of falling debris, says USGS.

USGS suggests not staying in kitchens, dangerous places put there are more things that can fall on one.

ON THE STREET OR IN OPEN PLACES Edit

Get away from buildings, poles and electrical cables, recommends Onemi.

Protect your head and neck with your arms.

If you drive a car, slow down and stop in a safe place. USGS recommend moving the car away carefully from traffic as much as possible. Avoid bridges and posts and stay inside the car until the earthquake stops.

If you are in a mountainous area, USGS explains that you have to be aware of falling rocks, landslides and moving away from trees that can fall on them.

HOW TO COMMUNICATE Edit

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Send text messages and social networks just to communicate and be informed, following the recommendations of the authorities, says Onemi.

USGS says the phone should not be used except for a medical or fire emergency, as it could congest the lines needed for emergency personnel response.

ON THE COAST: WHAT TO DO IN CASE OF TSUNAMI Edit

Move immediately to high places away from the coasts and beaches, indicate the Tsunami Warning Center of the United States National Climate Service (NOAA). Although not all earthquakes cause tsunamis, many do, and if an earthquake occurs near or in the ocean, the probability of a tsunami increases, so those who live in coastal regions must be prepared for an emergency.

A tsunami is not a single big wave, but a series of waves, and the largest one can reach the coast hours later, NOAA explains. If it's night, you have to be attentive to the sound of the sea.

For those in a boat or boat, NOAA recommends.

FLOODING Edit

A flood consists of the invasion or covering of water in areas that normally remain dry, it is also considered as the excessive abundance of something or thing; for example, "there is a flood of mosquitoes in the house."

Floods are caused when all the water cannot absorb the soil and vegetation when it rains, it flows without the rivers being able to channel it or the natural ponds or artificial swamps created by means of dams can retain it. River floods are the result of heavy rain or torrential rain, which sometimes snow melts, and the rivers overflow. Coastal areas are flooded due to unusually high tides caused by strong winds on the ocean surface, or by a tsunami or tsunami.

Much of the earth's surface is affected by floods, especially the equatorial and tropical areas. Among the rains that produce large floods are those caused by the summer gaps of Asia and Oceania, cyclones in the Caribbean area such as the El Niño phenomenon, which affects much of Central and South America.

Floods damage property, threaten the lives of humans and animals, erode the soil and sediment excessively, hinder drainage and prevent the land from being exploited productively.

Other effects of the floods in conjunction with the rains are that they cause landslides and landslides that destroy houses and human lives, as well as the supports of the bridges, the cant of the roads, and other structures, in addition to navigation and hydroelectric power supply.

The rain is, in many parts of the world, very welcome, but when the water falls very hard or for a long time, there comes a time when the land and the drainage channels of towns and cities can no longer absorb it.

And of course, being the water a liquid and, therefore, an element that makes its way there, unless the clouds disperse quickly we will have nothing left but to talk about floods. But what are they and what causes them?

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What are they? Edit

Floods are the occupation by water of areas that are usually free from it. They are natural phenomena that have been happening since there is water on planet Earth, shaping the coasts, contributing to the formation of the plains in the valleys of the rivers and fertile lands.

What causes them? Edit

They can be caused by various phenomena, which are:

Cold drop: occurs when the surface temperature of the earth is colder than that of the seas. This difference causes the rise of a large mass of hot and humid air to the middle and upper layers of the atmosphere, thus causing torrential rains and, as a consequence, there may be floods.

In Spain it is an annual phenomenon that occurs from autumn.

Monsoon: the monsoon is a seasonal wind that is produced by the displacement of the equatorial belt. It is caused by the cooling of the earth, which is faster than that of water. Thus, in summer the surface temperature of the earth is higher than that of the ocean, which causes the air above the ground to rise rapidly causing a storm. Wind, as it blows from anticyclones (high pressure areas) to cyclones (low pressure areas) to balance both pressures, an intense wind is constantly blowing from the ocean. As a result, the rains fall with intensity, increasing the level of the rivers.

Hurricanes: Hurricanes or typhoons are meteorological phenomena that, apart from being able to cause a lot of damage, are some of the ones that drop the most water. They are stormy systems with closed circulation that revolves around a low pressure center while feeding on the heat of the ocean, which is at a temperature of at least 20 degrees Celsius.

Thaw: in areas where it snows very frequently and also does it abundantly, sudden rises in temperature cause floods in the rivers. It can also occur if the snowfall has been strong and unusual, such as those that rarely occur in areas of sub-arid or arid climate.

Tsunamis or tsunamis: these phenomena are another possible cause of a flood. Giant waves caused by earthquakes can devastate the coast, causing many problems for both residents and the flora and fauna of the place.

They occur especially in the Pacific and Indian areas, which have a greater seismic activity.

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What to do in case of flooding? Edit

How do we prepare? Edit

Let's develop the family emergency plan together. It is simple and can save the life of our family.

· With family members prepare the emergency case, with non-perishable food, radio, focus, personal documents, medicines and protectors to cover the nose.

· Organize the family to plan how to act in case of flooding.

· If we live near rivers, streams, hillsides and hills, we protect the reserves and biological or forest areas, let's avoid their deforestation.

Do not build in flat areas near rivers or streams where there is a high incidence of flooding.

· Avoid depositing rubbish or debris in riverbeds and streams or on slopes near them.

· Clean the riverbeds, streams and ditches.

· Remove existing obstructions in sewers to avoid overflows.

· We evaluate the site of the house and that of the community, with information on existing risks, consult the municipality and other authorities and agencies in prevention and emergency care.

· Check with the community and the Municipal Emergency Committee for evacuation routes and the safest places for temporary shelters.


Prepare and update the family and community emergency plan.

Let's keep informed about the occurrence of heavy rains, storms and hurricanes.

· Be attentive to the official messages issued by the CNE.


If we observe that it starts to rain heavily or for a long time and we live in an area of ​​constant overflows or floods, WE STAY ALERT.

CLIMATE CHANGES Edit

Climate changes include heavy rains, frequent storms for a short period and heat waves that generate an accelerated melting of snow and ice. Monsoons cause severe flooding in countries near the equator. Cyclones and hurricanes generate waves that flood the coast and areas located on river plains. Tsunamis, seismic waves of large bodies of water caused by earthquakes, volcanic eruptions, large landslides and other changes in the seabed, can cause tidal waves that result in death and property

MAN MADE FACTORS Edit

When man modifies characteristics of the terrain that help direct or drain the water, the resulting changes can cause flooding. Forest logging and loss of vegetation as a result of overgrazing or cultivation result in the loss of land that separates and limits rivers, growing their bed and causing flooding. Changes in the channel of a stream and poor construction of dikes can generate flooding in a different area. Sometimes, floods occur when land and vegetation that can absorb water are replaced by buildings, concrete and asphalt, especially when urbanization develops near lakes, rivers and seas. The installation of storm drains to channel the water under the earth and that flow into streams and rivers can cause floods when the water flows quickly to the streams and raises the water level in an accelerat

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FACTOR COMBINATIONS Edit

Floods can be the result of a combination of factors that occur at the same time. When the barometric pressure is high and strong winds cause storms that produce a particularly high tide, the result is likely to be a flood. High tides produced in a low coastal area cause localized flooding. Floods can occur when a large amount of snow is heated on a volcanic mountain as well as when natural dikes break

Economy

Without a doubt, communities that suffer the effects of flooding require large sums of money to rebuild the infrastructure. All these costs add up, and the destruction also means a loss of income for companies, which ultimately ends up being a considerable cost to the community. Floods can also have global economic effects, if the country affected by the floods has had a lot of its products damaged, then there will be less supply available and, therefore, prices will increase, not only for its citizens, but for nations to which it exports, who depend on those resources.

Environment

Floods can cause damage to agricultural land, which damages crops and food supplies. Prolonged soil saturation can hinder the production of crops, which require a high concentration of oxygen to survive. If they immerse themselves in water, they cannot carry out the functions they need to grow. Floods can also spread pollution, since flood waters cause pollutants to be washed and spread to other parts of the environment. They can also displace animals such as rodents and snakes, leading to potentially dangerous conditions for both humans and animals.

Health

Flood disasters represent a risk to public health. Water sources can be contaminated with toxic materials that increase the risk of transmission of fecal-oral diseases. In addition, waterborne pathogens are another threat to those who have to constantly walk through the deep waters caused by the flood. Unsanitary and overcrowded conditions in relief shelters often also lead to an increased risk of disease.

PEOPLE Edit

The effects of flooding on the peoples of the earth are many. People can suffer injuries due to things such as fallen trees, power lines and other debris. Even a minor injury, such as a cut in the leg, can be fatal if it becomes infected and there is limited access to hospitals. Floods destroy houses and lead people to be displaced or homeless. Relief shelters fill up and cannot accommodate everyone. In addition to physical factors, flood victims may also suffer from mental disorders such as posttraumatic stress disorder, and this will have an impact on their ability to continue

Representing approximately one third of natural disasters and more than half of the deaths related to these events in the world, flooding is one of the worst manifestations of nature's wrath. The direct and indirect consequences of flooding vary from property damage to irreversible changes in the ecosystem. Due to its unpredictable nature, the high maintenance costs of flood control systems and the lack of education on proper preparation, most people can only face their consequences.

Car damage

In some cases, floods pose the same risks as a car accident. Floods, especially in urban areas, can cause minor or irreparable damage to cars. While structural damage to the exterior and interior of the vehicle is evident and can be repaired immediately, electrical and safety systems may be compromised, although the damage suffered will be manifested later. Corrosion may appear some time later and electrical wiring may weaken as a result of immersion in water.

Home damage

Floods can cause a lot of damage to a home, which affects from the foundations to the roof, which affects walls and baseboards. In addition to structural damage, mold, germs and other bacteria that cause disease can spread in certain places that have not been cleaned and dried immediately.

Electrical systems and appliances can be easily damaged during a flood. To determine the replacement or conditioning of certain elements related to electricity, professional help is required. While running water systems may be intact, nothing guarantees that contaminants have not entered the pipes. Floods can cause obstructions in drainage and sewer systems, causing serious health concerns.

Social and economic impact on a large scale

Floods alter everyday life. Even once the water recedes, damage to public infrastructure can cause disturbances in electrical, aquifer and communications systems, transit, work, schools and other social and economic activities. Food shortages, the proliferation of various diseases and sometimes forced migration are frequent after a flood. Among the long-term effects of flooding are poverty and depression due to the loss of property or loved ones.

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Ecosystem damage

Floods cause erosion, alteration or redirection of rivers or natural water sources. Farmland can be easily washed. Depending on the strength of the flood, the implications may vary from simple alterations in the landscape to a decrease in agricultural productivity and may even endanger local NATURE and wildlife.

Car damage

In some cases, floods pose the same risks as a car accident. Floods, especially in urban areas, can cause minor or irreparable damage to cars. While structural damage to the exterior and interior of the vehicle is evident and can be repaired immediately, electrical and safety systems may be compromised, although the damage suffered will be manifested later. Corrosion may appear some time later and electrical wiring may weaken as a result of immersion in water.

Home damage

Floods can cause a lot of damage to a home, which affects from the foundations to the roof, which affects walls and baseboards. In addition to structural damage, mold, germs and other bacteria that cause disease can spread in certain places that have not been cleaned and dried immediately.


Electrical systems and appliances can be easily damaged during a flood. To determine the replacement or conditioning of certain elements related to electricity, professional help is required. While running water systems may be intact, nothing guarantees that contaminants have not entered the pipes. Floods can cause obstructions in drainage and sewer systems, causing serious health concerns.

Social and economic impact on a large scale

Floods alter everyday life. Even once the water recedes, damage to public infrastructure can cause disturbances in electrical, aquifer and communications systems, transit, work, schools and other social and economic activities. Food shortages, the proliferation of various diseases and sometimes forced migration are frequent afterwards

Before a flood ...

Flood Watches / Warnings (Flood Watches / Warnings)

A flood alert is issued when the volume of rain is strong enough to cause the rivers around an area to overflow.

Flood warnings describe the severity of the situation and indicate when and where the flood will begin.

Flash flood watches are issued when heavy rains begin or are expected to cause a flood. As the name implies, they are emitted when the flood is sudden. If it occurs during a storm, it is recommended that you immediately seek to locate yourself in the highest possible terrain.

Protect yourself, your family and your property

In case of evacuation ...

Have an evacuation plan and establish a route for it.

Agree beforehand on a communication plan with your family members, in case they are separated during a flood.

To protect your property ...

If you move to a house or apartment, or settle in a new place of business, make sure you have sufficient insurance coverage, including flood insurance. You can find help from several sources that will tell you if your property is located in an area prone to flooding and is therefore at risk of suffering; Ask your bank, financier or mortgage lender or directly to the insurance agent.

HURRICANE Edit

What is it? Edit

It is a storm system that circulates around a center of low pressure and generates strong winds and rains.It is known as the eye of the hurricane the area of air that is usually free of clouds.

With regard to the energy of the hurricane,it comes from the condensation of airevhumedo.It should be noted that the violence of the wind causes hurricane to have destructive effects and bring down entire cities.

What causes it? Edit

They usually begin as a small mass of clouds on one side of the etorial line,developing through warm seas,with a temperature around 80° F (26° C). The atmospheric pressure is reduced,since the humidity and the increased hot air forms a depression.Within this depression,atmospheric moisture condenses to from storm clouds.The empty space left by the hot air bends upward,promoting the development of circulating winds.These revolving winds gradually increase the speed.Finally,a hurricane develops and sets in motion,fueled by a constant flow of warm and humid air.Therefore,the surface warm temperatures from the sea in the equatorial regions,which promote the large masses of hot and humid air,are the main driving force behind hurricanes.

What are its consequences? Edit

WINDS

They can cause tornadoes and fierce air currents,which destroy,lift and drag water,dust,mud,trees,heavy objects and scompro causing human and material damage.

RAINS

They cause floods and landslides,with fatal consequences,as well as damage to property and material goods.

WAVES

The tide increases with strong swells that can be quite dangerous

INJURIES

Once the hurricane is removed,it leaves destruction after its passage,whit dead and millions lost.

HOW TO SURVIVE A HURRICANE Edit

Be prepared Edit

1.Have plenty of food and water at home for a week.

2.Install protection on windows,sliding doors and garage doors.

3.Follow the established guidelines in case of disasters if you live in an area that can be flooded.

4.Ask an engineer to check your house and tell you how to make it more windproof.

Before of during a hurricane Edit

Before Edit

1.Stay informed.

2.Do not leave if not required.

3.Keep your important personal document close.

4.Keep items like warm clothing or rain coat and hand

5.Cover items that can be damaged with plastic.

During Edit

1.Keep calm.

2.Keep a portable radio nearby

3.Unplug appliances and energy from your home.

4.Get away from doors and windows.

5.Close that water and gas stopcoks.

After an hurricane Edit

1.Follow the instructions of the authorities and report damages and injuries.

2.Stay home if there is no damage.

3.Drink bottled or boiled water.

4.The water,electricity and gas services are disconnected.

5.Use the phone in case of emergency.

Volcano eruptions Edit

What is it ? Edit

volcanic eruption occurs when hot materials from the Earth's interior are thrown out of a volcano. Lava, rocks, dust, and gas compounds are some of these "ejecta".

Eruptions can come from side branches or from the top of the volcano. Some eruptions are terrible explosions that throw out huge amounts of rock and volcanic ash and can kill many people. Some are quiet outflows of hot lava. Several more complex types of volcanic eruptions have been described by volcanologists. These are often named after famous volcanoes where that type of eruption has been seen. Some volcanoes may show only one type of eruption during a period of activity, while others may show a range of types in a series.

Types of volcanoes Edit

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  • the three main types of volcanoes are

strato volcano: a colonial volcano consisting of layers of solid l�ava flows

mixed with layers of other rock

cinder cone volcano: doesn't have horizontal layers

  • shield volcano —  a type of volcano built entirely or mostly from fluid lava vents. They are named like this because when viewed from above, you can see just how massive and imposing they are – like a warrior’s shield.

How to survive to a volcano eruption? Edit

In each edition of “How to Survive a Disaster,” we discuss best practices for preparing for and surviving all of the most common—and even some of the least common—disasters.

Volcanoes are nothing to mess with, so if you live near one or plan on visiting one, there are some things you’ll want to consider.

If you live near a volcano: Edit

Millions of people live near volcanoes. From Italy’s Mount Vesuvius to Hawaii’s Kilauea, there are plenty of populated areas nestled in the shadows of volcanoes. The Indonesian island Java, for example, is home to more than 120 million people living near 30 volcanoes. National Geographic reports that these volcanoes have been fatal for over 140,000 people in the last 500 years. Death doesn’t just come from lava, either. Suffocating mud, toxic smoke, and even tsunamis can occur as a result of a volcanic explosion.

Preparing before an eruption Edit

If you live near an active volcano, there’s a lot you’ll want to consider. Preparing ahead of time is the best way to mitigate the threats volcanoes can bring to you and your family. Be sure to pay attention to local reports related to volcanoes. While some volcanoes erupt without warning, some do give geological signals that suggest an impending eruption and warning systems will keep you posted on what might happen. The following are guidelines from both the Center for Disease Control (CDC) and the Federal Emergency Management Agency (FEMA).

Considerations to make before eruption Edit

  • Review evacuation routes
  • Understand emergency alert systems
  • Create evacuation and preparedness plans
  • Prepare emergency kit (bug-out bag) and food supplies

Survival during an eruption Edit

  • Close all windows, doors, and fireplace or woodstove dampers
  • Turn off all fans and heating and air conditioning systems
  • Bring pets and livestock into closed shelters
  • Keep necessities on hand
  • Listen for emergency alerts and do what they say
  • Stay inside until you hear that it’s safe to come out
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TsunamiEdit

What is a tsunami? Edit

A tsunami is a complex event that involves a group of waves in a body of water of great energy and of variable size that occur when some extraordinary phenomenon, for example, a tsunami, volcanic eruption, or other underwater explosion vertically displaces a large body of water

What is the cause of a tsunami? Edit

Most tsunamis are caused by large earthquakes beneath the aquatic surface. For a tsunami to originate, the seabed must be abruptly moved vertically, so that a large body of ocean water is driven out of its normal equilibrium.

This natural phenomenon can be caused by landslides, volcanic eruptions, earthquakes and very rarely, meteor impacts that generate sudden movements at the bottom of the ocean. However, in most cases, tsunamis are caused by strong underwater earthquakes. Here are some factors:

What are the consequences of a tsunami? Edit

Tremors Edit

Most of the tsunamis recorded are due to strong earthquakes at the bottom of the ocean, as a result of tectonic plate movements. When these plates suddenly move, they cause an earthquake that, in turn, causes the water above it to move.

Explained in another way, a tsunami is like the effect of an earthquake on the surface of the earth. This means that when the plates (rocks) break or slide over each other in the fault lines below the ocean, the shock waves that occur due to the energy of the earth's reserve escapes through the Earth's crust beneath the seas.

As a result, the vast amounts of seismic energy released in the form of an earthquake under the sea suddenly push the ocean floor. This abruptly displaces a large amount of water that disperses outward in all directions from the epicenter of the earthquake.

The damages caused by a tsunami are commonly worse in the areas most adjacent to the underwater earthquake, mainly because seismic waves will reach the coastline so quickly and with a powerful force. Sometimes, the force of the seismic waves in the middle of the seas recedes due to the expansion of the Pacific.

What steps to take before a tsunami? Edit

· It is recommended to follow these safety and prevention tips against a possible tsunami:

· When in coastal areas, pay attention to possible tsunami alerts.

· Organize an evacuation route that leads to higher ground.

· Watch for certain signs that warn of the arrival of a tsunami, such as the rapid rise or fall of water on the coast.

· Never stay near the shore to see a tsunami coming.

· A tsunami is formed by a series of waves. Do not return to a coastal area affected by a tsunami until the authorities indicate that it is safe.

· Consider getting flood insurance.

· You should know that, often, a tsunami comes after an earthquake.

· Understand that if you get caught in the middle of a tsunami, you should not fight the current, as you could drown.

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