Based on data from the Sentinel-1A satellite, this image shows how and where the land uplifted and sank from the 7.8-magnitude earthquake that struck Nepal on 25 April 2015. The image was generated by the German Aerospace Center (DLR) Earth Observation Center (EOC) using data acquired by Sentinel-1A before and after the earthquake event. Image: DLR/EOC.


Sudden movement of a block of the Earth’s crust along a geological fault and associated ground shaking (IRDR Glossary).

Earthquake can be defined as the shaking of earth caused by waves moving on and below the earth's surface and causing: surface faulting, tremors vibration, liquefaction, landslides, aftershocks and/or tsunamis (WHO).


Facts and figures

The size or magnitude of earthquakes is determined by measuring the amplitude of the seismic waves recorded on a seismograph and the distance of the seismograph from the earthquake. These are put into a formula which converts them to a magnitude, which is a measure of the energy released by the earthquake. For every unit increase in magnitude, there is roughly a thirty-fold increase in the energy released. Earthquake magnitude was traditionally measured on the Richter scale. It is often now calculated from seismic moment, which is proportional to the fault area multiplied by the average displacement on the fault (Australian Government).

There are four different types of earthquakes: tectonic, volcanic, collapse and explosion.

  • A tectonic earthquake is one that occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates that cause physical and chemical changes.
  • A volcanic earthquake is any earthquake that results from tectonic forces which occur in conjunction with volcanic activity.
  • A collapse earthquake are small earthquakes in underground caverns and mines that are caused by seismic waves produced from the explosion of rock on the surface.
  • An explosion earthquake is an earthquake that is the result of the detonation of a nuclear and/or chemical device.

Related content on the Knowledge Portal

GP-STAR factsheet

Publishing institution: International Centre for Integrated Mountain Development (ICIMOD)

Close to 2000 landslides were mapped using a high-resolution image of the post 2015 Nepal Earthquake made available through International Charter for Space and Major Disaster, and Sentinel Asia. The images were geo-referenced if not done prior to visual scanning for a fresh scar from landslide and rockslide. Cross-checking with pre-event images most of which are available on Google Earth helped confirm whether or not the event is related to the earthquake. There are many large glacial lakes in and around the earthquake affected region, which was regularly monitored using multi-temporal high-resolution satellite data to pick up signs of potential failure. Mapping of landslide and monitoring of glacial lake using earth-observation data provided much needed situational awareness on the geo-hazard situation.


Publishing institution: United Nations Office for Outer Space Affairs (UNOOSA)
After the TAM was conducted in Myanmar, innovative impacts were completed following a recommendation. “Emergency Operation Centre (EOC)”, which is comprised of four units including “Remote Sensing Unit” and “Risk Assessment and Emergency Response Unit” was established in the Ministry of Social Welfare, Relief & Resettlement (MSWRR). The capacity building of MSWRR and other related institutes in remote sensing and GIS were strengthened. The Disaster Management Training Centre now conducts courses in remote sensing/GIS. Myanmar has also become the first country in ASEAN to apply for universal access to the International Charter. Myanmar government is aware of the National Spatial Data Infrastructure (NSDI) and one map policy that has been initiated by the Ministry of Education is very crucial.  
Publishing institution: United Nations Office for Outer Space Affairs (UNOOSA)

In order to encourage the targeted retrieval of space-based information and data by disaster risk reduction practitioners, content on the Portal is systematically enriched with metadata. For instance, data sources are marked up with data about their file type, satellite/sensor and spatial coverage and whether they relate to the disaster risk management or emergency response phase. The tool features a range of filters that draw on the metadata, thereby allowing users to narrow down their search, for example, filtering available GIS software by hazard type. This ensures that users efficiently find the content that is most relevant to them. At the same time, the Portal encourages the discovery of resources related to those accessed by the user, by providing links to them on the same page. This allows for contextualisation and highlights links between resources from different areas that other platforms may display in an isolated fashion. A dynamic glossary, which means that terms in... read more

Publishing institution: UNITAR Operational Satellite Applications Programme (UNOSAT)

Based on optical and radar images of different resolutions, UNOSAT products are also enriched with the available baseline GIS datasets and crowdsourcing data. Satellite-derived analysis performed by UNOSAT is delivered in the form of GIS Data, Static Maps, Live Web Maps, and Reports, and is then shared with a wide range of end-users such as UN Agencies, International Organizations, and Governments.

Publishing institution: Joint Research Center, European Commission (JRC)

The Global Human Settlement (GHS) framework produces global open source spatial information about the human presence on the planet over time. This is in the form of built up maps, population density maps and settlement maps. This information is generated with evidence-based analytics and knowledge using new spatial data mining technologies. The framework uses heterogeneous data including global archives of fine-scale satellite imagery, census data, and volunteered geographic information. The data is processed fully automatically and generates analytics and knowledge reporting objectively and systematically about the presence of population and built-up infrastructures. 

Publishing institution: International Working Group on Satellite Emergency Mapping (IWG‐SEM)

The guidelines will be reviewed and updated periodically, in order to integrate new best practices and to be responsive to evolutions in technology and end-user needs. The IWG-SEM chair has the responsibility to initiate the review, by agreement of the Working Group. 

The production and the maintenance of the guidelines are based on a joint effort by the members of the International Working Group on Satellite-based Emergency Mapping (IWG- SEM), a voluntary group of organizations involved in satellite-based emergency mapping. It was founded to improve cooperation, communication and professional standards among the global network of satellite-based emergency mapping providers. The chairperson of the group is nominated for a term of one year and is responsible for organizing the monthly telecons and bi-annual meetings. The current chair is from the Department of Geoinformatics, Z_GIS University of Salzburg / Spatial Services Ltd, Austria.

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