Natural Hazards

Natural Hazards
SEDACMaps · CC BY 2.0 · source
Name	Natural hazards
Type	Environmental phenomenon

Natural Hazards Natural hazards are naturally occurring physical events that pose threats to life, property, infrastructure, and ecosystems. They intersect with many historical episodes such as the Great Famine of 1315–1317, scientific investigations like the Mount St. Helens eruption studies, and institutional responses from bodies such as the World Health Organization and the United Nations Office for Disaster Risk Reduction. Their study draws on evidence used in analyses of events like the 2004 Indian Ocean earthquake and tsunami, Hurricane Katrina, and the 2011 Tōhoku earthquake and tsunami.

Definition and Classification

Definitions of hazards have been codified in instruments and by agencies including the Sendai Framework for Disaster Risk Reduction, United Nations agencies, and national bodies such as the Federal Emergency Management Agency and the United Kingdom Met Office. Classification schemes distinguish geophysical hazards linked to the Ring of Fire and regions like California, hydrological hazards relevant to the Ganges basin and Mississippi River, climatological hazards studied in contexts such as El Niño–Southern Oscillation and North Atlantic Oscillation, and biological hazards examined by institutions like the Centers for Disease Control and Prevention and the European Centre for Disease Prevention and Control. Historical taxonomies reference events including the 1883 eruption of Krakatoa, the 1906 San Francisco earthquake, and the 1918 influenza pandemic when delineating hazard categories.

Types of Natural Hazards

Geophysical hazards: earthquakes exemplified by the Great Chilean earthquake, volcanic eruptions such as Mount Vesuvius, landslides like the Hpakant landslide, and tsunamis observed after the 1960 Valdivia earthquake. Meteorological hazards: tropical cyclones including Typhoon Haiyan, extratropical storms like the Great Storm of 1987, and tornado outbreaks such as the 2011 Super Outbreak. Hydrological hazards: floods seen in the 2010 Pakistan floods, flash floods like those in the Kedarnath disaster, and glacier lake outburst floods in regions such as the Himalayas. Climatological hazards: droughts including the Sahel droughts, heatwaves like the 2003 European heat wave, and wildfires exemplified by the 1983 Ash Wednesday bushfires and the 2019–20 Australian bushfire season. Biological hazards: pandemics such as the COVID-19 pandemic, vector-borne disease outbreaks like Zika virus outbreaks, and invasive species incidents such as the Cane toad in Australia.

Causes and Driving Processes

Plate tectonics underlying seismicity and volcanism are studied via networks including the International Seismological Centre and field campaigns in regions like the Pacific Northwest and the Andes. Atmospheric dynamics driving storms and cyclones are analyzed through programs such as NOAA Hurricane Research Division and the European Centre for Medium-Range Weather Forecasts. Hydrological extremes reflect catchment processes in basins like the Mekong River and Yangtze River and are influenced by cryospheric changes linked to Greenland ice sheet and Antarctic ice sheet mass balance. Human interactions with hazardous processes appear in cases involving urban expansion in Tokyo, land-use change in the Amazon rainforest, and coastal development along the Gulf Coast. Long-term drivers include climate variability discussed in reports by the Intergovernmental Panel on Climate Change and geological cycles recognized since studies of the Pleistocene glaciations.

Risk Assessment and Hazard Mapping

Risk assessment methodologies draw on statistical records from archives such as the EM-DAT database and hazard models developed by research centers at institutions like Massachusetts Institute of Technology, Imperial College London, and the Swiss Federal Institute for Forest, Snow and Landscape Research. Hazard mapping uses remote sensing from satellites such as Landsat, Sentinel-2, and platforms operated by the European Space Agency and NASA. Probabilistic seismic hazard analysis applied in projects like the Global Seismic Hazard Assessment Programme and flood inundation mapping used in the Netherlands Delta Works inform planning. Exposure and vulnerability analyses reference demographic data from the United Nations Population Fund and economic loss accounting similar to studies on Hurricane Maria and the 2010 Haiti earthquake.

Impacts on Society, Economy, and Environment

Hazard impacts manifest in human fatalities and displacement recorded after the 2005 Kashmir earthquake, economic losses estimated for events like Hurricane Sandy, and ecosystem disruption observed after the Deepwater Horizon oil spill and major volcanic eruptions such as Mount Pinatubo. Social consequences include migration patterns traced in studies of the Dust Bowl and public health burdens reviewed after the 2014 West Africa Ebola epidemic. Infrastructure failures documented during the Tohoku tsunami and supply-chain disruptions noted in analyses of the 2011 Tōhoku earthquake and tsunami highlight cascading risks. Cultural heritage losses have occurred at sites such as Pompeii and in floods affecting Venice.

Mitigation, Preparedness, and Early Warning

Mitigation measures include engineering standards used in California seismic codes, flood defenses exemplified by the Maeslantkering and the Three Gorges Dam, and ecosystem-based adaptation projects like mangrove restoration in the Mekong Delta. Preparedness programs are organized by agencies such as the Japan Meteorological Agency, National Oceanic and Atmospheric Administration, and humanitarian organizations including the International Federation of Red Cross and Red Crescent Societies and Doctors Without Borders. Early warning systems combine monitoring networks from the Pacific Tsunami Warning Center, satellite products from NOAA GOES, and forecasting centers such as the UK Met Office to alert populations in contexts like the Indian Ocean and the Caribbean Sea.

Case Studies and Notable Events

Representative case studies include the 2004 Indian Ocean earthquake and tsunami—which reshaped international warning systems and humanitarian response—the 2010 Haiti earthquake—which revealed governance and infrastructure vulnerabilities—and the 2019–20 Australian bushfire season—which illustrated links between climate extremes and ecosystem resilience. Comparative historical episodes such as the 1755 Lisbon earthquake, the 1816 Year Without a Summer after the Mount Tambora eruption, and the Great Galveston Hurricane of 1900 inform contemporary policy debates in fora like the United Nations and research consortia including the Global Facility for Disaster Reduction and Recovery.

Category:Hazards