Natural hazard

San Francisco was devastated by an earthquake in 1906
Puʻu ʻŌʻō
Young steer after a blizzard, March 1966
Hurricane Katrina

Natural phenomenon that might have a negative effect on humans and other animals, or the environment.

- Natural hazard

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Avalanche

Rapid flow of snow down a slope, such as a hill or mountain.

A powder snow avalanche in the Himalayas near Mount Everest.
Heavy equipment in action after an avalanche has interrupted service on the Saint-Gervais–Vallorcine railway in Haute-Savoie, France (2006).
The terminus of an avalanche in Alaska's Kenai Fjords.
Loose snow avalanches (far left) and slab avalanches (near center) near Mount Shuksan in the North Cascades mountains. Fracture propagation is relatively limited.
15 cm deep, soft slab avalanche triggered by a snowboarder near Heliotrope Ridge, Mount Baker in March 2010. Multiple crown fracture lines are visible in the top-middle of the image. Note the granular characteristic of the debris in the foreground that results from the slab breaking up during descent.
Avalanche on Simplon Pass (2019)
In steep avalanche-prone terrain, traveling on ridges is generally safer than traversing the slopes.
A cornice of snow about to fall. Cracks in the snow are visible in area (1). Area (3) fell soon after this picture was taken, leaving area (2) as the new edge.
Avalanche path with 800 m vertical fall in the Glacier Peak Wilderness, Washington state. Avalanche paths in alpine terrain may be poorly defined because of limited vegetation. Below tree line, avalanche paths are often delineated by vegetative trim lines created by past avalanches. The start zone is visible near the top of the image, the track is in the middle of the image and clearly denoted by vegetative trimlines, and the runout zone is shown at the bottom of the image. One possible timeline is as follows: an avalanche forms in the start zone near the ridge, and then descends the track, until coming to rest in the runout zone.
After surface hoarfrost becomes buried by later snowfall, the buried hoar layer can be a weak layer upon which upper layers can slide.
After digging a snow pit, it is possible to evaluate the snowpack for unstable layers. In this picture, snow from a weak layer has been easily scraped away by hand, leaving a horizontal line in the wall of the pit.
United States Forest Service avalanche danger advisories.
Snow fences in Switzerland during summer.
Avalanche blasting in French ski resort Tignes (3,600 m)
Avalanche warning sign near Banff, Alberta
Radar station for avalanche monitoring in Zermatt.
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In mountainous areas, avalanches are among the most serious natural hazards to life and property, so great efforts are made in avalanche control.

Geophysics

Subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis.

Age of the sea floor. Much of the dating information comes from magnetic anomalies.
Computer simulation of the Earth's magnetic field in a period of normal polarity between reversals.
A map of deviations in gravity from a perfectly smooth, idealized Earth.
A model of thermal convection in the Earth's mantle. The thin red columns are mantle plumes.
Illustration of the deformations of a block by body waves and surface waves (see seismic wave).
Earth's dipole axis (pink line) is tilted away from the rotational axis (blue line).
Example of a radioactive decay chain (see Radiometric dating).
Seismic velocities and boundaries in the interior of the Earth sampled by seismic waves.
Schematic of Earth's magnetosphere. The solar wind flows from left to right.
Replica of Zhang Heng's seismoscope, possibly the first contribution to seismology.

Geophysics is applied to societal needs, such as mineral resources, mitigation of natural hazards and environmental protection.

Disaster

Serious problem occurring over a short or long period of time that causes widespread human, material, economic or environmental loss which exceeds the ability of the affected community or society to cope using its own resources.

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Painting of the Cathedral and the Academy building after the Great Fire of Turku, by Gustaf Wilhelm Finnberg, 1827
Haiti earthquake damage
Driving through flash flood
Airplane crashes and terrorist attacks are examples of man-made disasters: they cause pollution, kill people, and damage property. This example is of the September 11 attacks in 2001 at the World Trade Center in New York City.

Disasters are routinely divided into either "natural disasters" caused by natural hazards or "human-instigated disasters" caused from anthropogenic hazards.

Hazard

Potential source of harm.

A proposed level crossing at railroad tracks would result in "the worse death trap in Los Angeles", a California traffic engineer warned in 1915, because of the impaired view of the railway by automobile drivers. A viaduct was built instead.
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Ukrainian "danger" road sign. Stop for dangers, including traffic accidents, natural disasters or other road obstructions

Hazards can be classified in several ways; they can be classified as natural, anthropogenic, technological, or any combination, such as in the case of the natural phenomenon of wildfire becoming more common due to human-made climate change or more harmful due to changes in building practices.

Human impact on the environment

Human (or anthropogenic) impact on the environment refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans.

Chart published by NASA depicting CO2 levels from the past 400,000 years.
Reduction of one's carbon footprint for various actions.
Human population from 10000 BCE to 2000 CE, increasing sevenfold after the eighteenth century.
Lacanja burn
Fishing down the foodweb
Urban sprawl in California
Soil erosion in Madagascar
Worldwide, the animal industry provides only 18% of calories, but uses 83% of agricultural land and emits 58% of food's greenhouse gas emissions.
A village palm oil press "malaxeur" in Bandundu, Democratic Republic of the Congo
Child demonstrating for actions to protect the environment (2018)
Summary of major biodiversity-related environmental-change categories expressed as a percentage of human-driven change (in red) relative to baseline (blue)
The primary causes and the wide-ranging effects of global warming and resulting climate change. Some effects constitute feedback mechanisms that intensify climate change and move it toward climate tipping points.
Acid mine drainage in the Rio Tinto River
Smog in Beijing, China
Anti-nuclear protest near nuclear waste disposal centre at Gorleben in northern Germany
Kiviõli Oil Shale Processing & Chemicals Plant in ida-Virumaa, Estonia
The Wachusett Dam in Clinton, Massachusetts
Waste generation, measured in kilograms per person per day
Great Pacific garbage patch
Interstate 10 and Interstate 45 near downtown Houston, Texas in the United States
An Agent Orange spray run by aircraft, part of Operation Ranch Hand, during the Vietnam War
A composite image of artificial light emissions from Earth at night
The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy.

Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and bush fires.

Disaster risk reduction

Systematic approach to identifying, assessing and reducing the risks of disaster.

Villages have adapted the design of houses to protect people from rising flood waters and small boats are used to transport people and food to sustain livelihoods. This kind of disaster risk reduction is an important Climate change adaptation
Disaster risk reduction progress score for some countries
Landmines are also a hazard that cause much loss of life and injury. Female de-miners in Lebanon set off to clear landmines.
Chennai damage after 2004 Indian Ocean Earthquake
Different kinds of disasters

Within the field of disaster risk reduction, one widely-accepted definition of resilience comes from UNISDR: “The ability of a system, community or society exposed to hazards to resist, absorb, accommodate to and recover from the effects of a hazard in a timely and efficient manner, including through the preservation and restoration of its essential basic structures and functions.”

Beach evolution

Eroding the land.

Old sea level mark before these tremors.
New quay at the Bay of Pozzuoli
St. Mark's Square, Venice, during flooding
Coastal and oceanic landforms.
Five general coastal planning approaches.
Salt marsh during low tide, mean low tide, high tide and very high tide (spring tide).
Mangrove's above and below water view at the edge of the shore.
Main stages of Holocene evolution of the Rhone delta.
Southern California beach 10/97 (before winter storms boosted by El Niño)
Same location 4/98 (after winter storms boosted by El Niño)
Old German-built WWII bunkers at Capbreton, south-west of France
Holland coast
Holland coast recession
Sea wall in the Netherlands that does allow the tide and organisms through, but brakes wave energy.
Groyne at Mundesley, Norfolk, UK.
"Headland groyne" at East Coast Beach in Singapore consists of breakwater parallel to shore and connected to shore by a vertical groyne. Higher mainland is fortified with a low rise mud seawall which has been further stabilized by planting grass and trees.
Tetrapods, Marine Drive, Mumbai.
Dolos.
KOLOS.
Xblocs.
Gabion, welded wiremesh filled with stone.
A series of trellises forms the wall of a garden room.
Creeping groundsel growing on a wooden trellis in Italy.
Casa Redonda, one of five nipa houses built by the Philippine national hero José Rizal during his exile in Dapitan.<ref name="nhcp2">{{cite web|url=http://nhcp.gov.ph/rizal-shrine-dapitan/|title=Rizal Shrine Dapitan|publisher=National Historical Commission|access-date=9 November 2014}}</ref>
The raised bale houses of the Ifugao people.<ref name="Sato1991">{{cite journal |last1=Sato |first1=Koji |title=Menghuni Lumbung: Beberapa Pertimbangan Mengenai Asal-Usul Konstruksi Rumah Panggung di Kepulauan Pasifik |journal=Antropologi Indonesia |date=1991 |volume=49 |pages=31–47 |url=http://www.sumai.org/asia/refer/sem9102.htm}}</ref>

Integrated coastal zone management minimizes the negative human impacts on coasts, enhances coastal defense, mitigates the risk associated with the sea level rise and other natural hazards.

Nature

Physical world or universe.

South Penghu Marine National Park of Taiwan, showing the wonder of nature
The Blue Marble, which is a famous view of the Earth, taken in 1972 by the crew of Apollo 17
Three types of geological plate tectonic boundaries
An animation showing the movement of the continents from the separation of Pangaea until the present day
Plankton inhabit oceans, seas and lakes, and have existed in various forms for at least 2 billion years
Blue light is scattered more than other wavelengths by the gases in the atmosphere, giving the Earth a blue halo when seen from space
Lightning
A tornado in central Oklahoma
The Iguazu Falls on the border between Brazil and Argentina
A view of the Atlantic Ocean from Leblon, Rio de Janeiro
Lake Mapourika, New Zealand
The Westborough Reservoir (Mill Pond) in Westborough, Massachusetts
The Nile river in Cairo, Egypt's capital city
A rocky stream in Hawaii
Loch Lomond in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period of time.
Lush green Aravalli Mountain Range in the Desert country – Rajasthan, India. A wonder how such greenery can exist in hot Rajasthan, a place well known for its Thar Desert
An aerial view of a human ecosystem. Pictured is the city of Chicago
Peñas Blancas, part of the Bosawás Biosphere Reserve. Located northeast of the city of Jinotega in Northeastern Nicaragua
Old growth European Beech forest in Biogradska Gora National Park, Montenegro
Female mallard and ducklings – reproduction is essential for continuing life
An area of the Amazon Rainforest shared between Colombia and Brazil. The tropical rainforests of South America contain the largest diversity of species on Earth
A microscopic mite Lorryia formosa
A selection of diverse plant species
A selection of diverse animal species
Despite their natural beauty, the secluded valleys along the Na Pali Coast in Hawaii are heavily modified by introduced invasive species such as She-oak
Aesthetically pleasing flowers
The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density
Planets of the Solar System (Sizes to scale, distances and illumination not to scale)
NGC 4414 is a spiral galaxy in the constellation Coma Berenices about 56,000 light-years in diameter and approximately 60 million light-years from Earth

The field is a major academic discipline, and is also important for mineral and hydrocarbon extraction, knowledge about and mitigation of natural hazards, some Geotechnical engineering fields, and understanding past climates and environments.

Economy of Madagascar

Market economy and is supported by Madagascar's well-established agricultural industry and emerging tourism, textile and mining industries.

The capital of Madagascar, Antananarivo
Change in per capita GDP of Madagascar, 1950–2018. Figures are inflation-adjusted to 2011 International dollars.
Tulear
Former President Marc Ravalomanana of Madagascar
Port Toamasina
Vibrant Antananarivo is the political and economic capital of Madagascar
Local market vendors.
Graphical depiction of Madagascar's product exports in 28 color-coded categories.

Nevertheless, natural hazards (cyclones, drought, locust invasions) combined with old-fashioned farming practices limit production.

Natural disaster

Global multihazard proportional economic loss by natural disasters as cyclones, droughts, earthquakes, floods, landslides and volcanoes
A blizzard in Maryland in 2009
Global death from natural disasters
A rope tornado in its dissipating stage, Tecumseh, Oklahoma.
Global damage cost from natural disasters
A daytime wildfire in California.
1755 copper engraving depicting Lisbon in ruins and in flames after the 1755 Lisbon earthquake. A tsunami overwhelms the ships in the harbor.
A landslide in San Clemente, California in 1966
Global Number of deaths from earthquake (1960-2017)
Global number of recorded earthquake events
The Limpopo River during the 2000 Mozambique flood
A classic anvil-shaped, and clearly-developed Cumulonimbus incus
A large hailstone, about 6 cm in diameter
Fallen trees caused by the Tunguska meteoroid of the Tunguska event in June 1908.
A wildfire in California.

A natural disaster is "the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community".