A tsunami is a series of travelling waves of extremely long length and period, generated when a large volume of ocean water is rapidly displaced by a sudden displacement of the seabed. These series of waves are generated by a displacement of massive amounts of water through underwater earthquakes, volcanic eruptions or landslides. Tsunami waves travel at very high speed across the ocean but as they begin to reach shallow water they slow down and the wave grows steeper (IRDR Glossary).

The majority of tsunami are generated by shallow large earthquakes in subduction zones. Tsunami is also known as seismic sea waves because it is most often generated by earthquakes (UNESCO).

Facts and figures

The word tsunami is derived from the Japanese word “tsu” and “nami”, meaning “Harbor” and “Wave” respectively.

The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Scientists can predict when a tsunami will arrive at various places by knowing the source characteristics of the earthquake that generated the tsunami and the characteristics of the seafloor along the paths to those places. When the ocean is over 19,685 feet (6,000 m) deep, unnoticed tsunami waves can travel over 500 mph (804.67 kmh). One coastal community may see no damaging tsunami wave activity while in another nearby community destructive waves can be large and violent. Reefs, bays, entrances to rivers, undersea features and the slope of the beach help to modify the tsunami as it approaches the coastline (NOAA).

Dependent on the distance of the tsunami from its source, it may be classified as a:

  • Local/near field tsunami A tsunami from a nearby source for which its destructive effects are confined to coasts less than 1 hour tsunami travel time or typically within about 100 km from its source.
  • Regional tsunami A tsunami that is capable of destruction in a particular geographic region.
  • Destructive tsunami Happens when tsunami waves become extremely large in height, they savagely attack coastlines, causing devastating property damage and loss of life. A small wave only 30 cm high in the deep ocean may grow into a much larger wave 30 m high as it sweeps over the shore.
  • Non-Destructive Tsunami Mostly happens as a result of minor earthquakes and/or other events. It can be due to the source being far away from land or the earthquake being too small to have any effect when approaching the shore. When a small tsunami comes to the shoreline it is often seen as a strong and fast-moving tide (Caribbean Tsunami Information Center).

UN-SPIDER Regional Support Offices with hazard-specific expertise

Related content on the Knowledge Portal

  • Gaofen-1 (gao fen = high resolution) is the first of a series of high-resolution optical Earth observation satellites of CNSA (China National Space Administration), Beijing, China. The civilian HDEOS (High-Definition Earth Observation Satellite) program was proposed in 2006, it received government approval and was initiated in 2010. China plans to launch six HDEOS spacecraft between 2013 and 2016. The major users of the observation data will be the Ministry of Land and Resources, Ministry of Environmental Protection, and the Ministry of Agriculture.
    The GF-1 spacecraft was launched on April 26, 2013 on a CZ-2D (Long March -2D) vehicle from the JSLC (Jiuquan Satellite Launch Center) in northwest China.

    PMC (PAN and Multispectral camera)
    WFI (Wide Field Imager)

  • Landsat 8 launched on February 11, 2013, from Vandenberg Air Force Base, California, on an Atlas-V 401 rocket, with the extended payload fairing
 (EPF) from United Launch Alliance, LLC. The Landsat 8 satellite payload consists of two science instruments—the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). These two sensors provide seasonal coverage of the global landmass at a spatial resolution of 30 meters (visible, NIR, SWIR); 100 meters (thermal); and 15 meters (panchromatic).
    Landsat 8 was developed as a collaboration between NASA and the U.S. Geological Survey (USGS). NASA led the design, construction, launch, and on-orbit calibration phases, during which time the satellite was called the Landsat Data Continuity Mission (LDCM). On May 30, 2013, USGS took over routine operations and the satellite became Landsat 8. USGS leads post-launch calibration activities, satellite operations, data product generation, and data archiving at the Earth...

    read more
  • Launched in December 2011, Pleiades is a constellation of two very-high-resolution satellites capable of acquiring imagery of any point on the globe in under 24 hours for civil and military users.
    Pleiades has been observing and mapping Earth’s surface at a resolution of just 70 cm every day since December 2011. Comprising the Pleiades 1A and Pleiades 1B satellites, this space imaging system complements the capabilities of the SPOT satellites, which have a wider field of view than Pleiades but lower spatial resolution. What’s more, as Pleiades 1A and 1B are in the same orbit, together they can image anywhere on Earth in less than 24 hours. Pleiades imagery is used for both civil and military applications, for example to track urban expansion, monitor the planet’s active volcanoes or assist road and railway routing, and to locate adversaries’ military installations for mission planning. Pleiades’ key asset is an extremely sensitive optical...

    read more
  • SJ-9 (Shi Jian = Practice) is a technology demonstration formation flight mission of CNSA (China National Space Administration), consisting of two minisatellites of different sizes and capabilities, SJ-9A and SJ-9B. The overall mission concept is to demonstrate the functionality of a range of newly developed formation flying techniques and components and to validate the formation flight GNC (Guidance, Navigation and Control) algorithms and strategies of the system configuration.
    SJ 9B carries the LWIR (Long Wave Infrared) Camera as a technology experiment. The goal of the LWIR camera is to test mainly the functions of the instrument such as the focal-plane component and the long-life Stirling cryocooler which is designed to function as an autonomic research and development component. The camera features low-temperature optics. The operational temperature of optical system is kept in the range of -35ºC to -20ºC.


    read more
  • SJ-9 (Shi Jian = Practice) is a technology demonstration formation flight mission of CNSA (China National Space Administration), consisting of two minisatellites of different sizes and capabilities, SJ-9A and SJ-9B. The overall mission concept is to demonstrate the functionality of a range of newly developed formation flying techniques and components and to validate the formation flight GNC (Guidance, Navigation and Control) algorithms and strategies of the system configuration.
    SJ 9A is based on the CAST-2000 bus. It conducts in-orbit experiments for electric propulsion, high-precision- and high-stability control systems, high-efficienent power supply and advanced thermal control technology. The satellite features also instruments for Earth observation and component tests of indigenously developed technology.

    Instruments: High-performance small camera
    - integrated panchromatic and multispectral design
    - swath width: 30km

    read more
  • VRSS-1 is Venezuela's first remote sensing satellite.
    On May 26, 2011, a contract for the manufacture and launch of the VRSS-1 spacecraft was signed in Caracas, Venezuela, between the government of Venezuela (the Ministry of People’s Power for Science, Technology and Intermediate Industries) and CGWIC (China Great Wall Industry Corporation), a subsidiary of CASC (China Aerospace Science & Technology Corporation).
    After launch, the VRSS-1 satellite was renamed in honor of Sebastián Francisco de Miranda (1750-1816), a Venezuelan revolutionary hero, known as ‘Generalissimo’ Francisco de Miranda, who had planned the independence of the Spanish colonies in South America.
    Partner organizations in the VRSS-1 program: ABAE is the Space Agency of Venezuela, subordinated and funded by the Venezuelan Ministry of People’s Power for Science, Technology and Innovation (MPPCTI). ABAE is in charge of in-orbit operations, management and application of...

    read more
  • SPOT-6 (Système Pour l’Observation de la Terre) is an optical satellite built by Astrium and was successfully launched on September 9, 2012 with SPOT 7 launched on June 30, 2014.
    The new generation SPOT-6 and 7 optical satellites feature technological improvements and advanced system performance allowing continuity in the SPOT constellation through to 2024. It is capable of imaging the Earth with a resolution of 1.5 meter panchromatic and 6 meter multispectral (blue, green, red, near-IR) and will offer imaging products to customers in defense, agriculture, deforestation, environmental monitoring, coastal surveillance, engineering, oil, gas and mining industries.
    The ability to respond accordingly to changing weather conditions, a reduced timeline for urgent tasking requests and an acquisition capacity of 3 million sq km per satellite shows an increased data capacity and simplified data access, major improvements in this generation of SPOT satellites.
    SPOT-6 and...

    read more
  • Kanopus-V (also spelling of Canopus-V N1) is an Earth observation minisatellite mission of the Russian Space Agency, Roskosmos and ROSHYDROMET/Planeta. The overall objective is to monitor Earth's surface, the atmosphere, ionosphere, and magnetosphere to detect and study the probability of strong earthquake occurrence.
    Essentially, it would be an imaging satellite designed to photograph the Earth surface with a resolution of 2.1 meters and a swath of 20 kilometers with its panchromatic camera and a resolution of 10.5 meters and a swath of 41 kilometers with a multispectral camera. Resulting images could be used for cartography, agricultural planning and similar applications.

    The Kanopus-V-N1 spacecraft was launched on July 22, 2012 on a Soyuz FG/Fregat vehicle from the Baikonur Cosmodrome, Kazakhstan. The launch provider was Starsem.

    PSS (Panchromatic Imaging System)
    MSS (Multispectral Imaging System)
    MSU-200 (...

    read more
  • Today, weather satellites scan the whole Earth, meaning not a single tropical storm or severe weather system goes undetected. The early detection and warnings they provide have saved thousands of lives.
    Meteosat data is of unique value to nowcasting of high impact weather in support of safety of life and property.
    It has been shown to improve weather forecasts and severe weather warnings which, in turn helps limit damage to property and benefits industry e.g. transport, agriculture and energy.
    Meteosat-10 provides the Rapid Scanning Service, delivering more frequent images every five minutes over parts of Europe, Africa and adjacent seas. It also provides Search and Rescue monitoring.

    GERB (Geostationary Earth Radiation Budget)
    MSG Comms (Communications Package for MSG)
    SEVIRI (Spinning Enhanced Visible and Infra-Red Imager)

    read more
  • KOMPSAT-3 is an optical high-resolution Korean observation mission of KARI (Korea Aerospace Research Institute). The mission is funded by MEST (Ministry of Education, Science and Technology). The project was started in 2004. The objective is to provide observation continuity from the KOMPSAT-1 and KOMPSAT-2 missions to meet the nation's needs for high-resolution optical imagery required for GIS (Geographical Information Systems) and other environmental, agricultural and oceanographic monitoring applications.

    A further goal is to meet the nation's satellite demand and form a technology infrastructure that will make inroads into the world space industry at a stage when the industry is improving the capability to design and develop highly advanced remote sensing satellites.

    Instrument: AEISS (Advanced Electronic Image Scanning System)
    - 5 spectral...

    read more

Term Parents

UN-SPIDER Regional Support Offices with hazard-specific expertise