Earthquake
Definition
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.
Further information
UN-SPIDER Regional Support Offices with hazard-specific expertise
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Data Source
News
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The high-priority Copernicus Radar Observation System for Europe in L-band (ROSE-L) mission is planned to launch in 2028 for a period of 7.5 years. The ROSE-L mission will orbit Earth every few days at an altitude of 690km and will carry a L-Band synthetic aperture radar (SAR). With a wavelength of approximately 23cm... read more
In order to discuss and promote the use of space technologies in addressing natural hazards such as forest fires and landslides in Latin America, UN-SPIDER conducted a virtual regional expert meeting on the topic of “Space-based Solutions for Disaster Risk Reduction and Emergency Response in Latin America” from 22 to 24 September 2020. The meeting was jointly organized with UN-SPIDER Regional Support Offices from Argentina (National Space Activities Commission, CONAE), Brazil (Federal University of Santa Maria, UFSM), Colombia (Geographic Institute Agustin Condazzi, IGAC), and Mexico (Mexican Space Agency, AEM).
In Latin America, UN-SPIDER and its Regional Support Offices have regularly carried out regional expert meetings, training courses and other joint efforts since 2011. The last Regional Expert Meeting took place in 2017 in Mexico.
The meeting, which consisted of three two-hour-long sessions, brought together a total of over 200 disaster management stakeholders... read more
According to the latest issue of an annual disaster statistics report, floods were the deadliest type of disasters in 2019, followed by extreme temperature, while storms affected the highest number of people. Published by the Centre for Research on the Epidemiology of Disasters (CRED), “Natural disasters 2019 - Now is the time to not give up” draws on data recorded in the Emergency Events Database (EM-DAT), which saw the addition of 396 disasters that affected a total of 95 million and caused $103 billion in economic losses around the world.
Accounting for 40 per cent of disaster events, Asia suffered the highest impact with 45 per cent of deaths and 74 per cent of total affected. India, which saw cyclone Fani cause destruction in 2019, was the country most affected... read more
Event
The University of Alaska Fairbanks has launched a MOOC about Synthetic Aperture Radar (SAR) remote sensing for disaster monitoring. SAR is a remote sensing technology that can see the ground even during darkness and through rain, clouds, or smoke. Participants of the course will gain an intuitive understanding of the information contained in SAR observations and learn to use a range of analysis techniques to apply SAR data to disaster mapping and management. Specific topics will include:
- The mathematical and physical principles of SAR remote sensing
- How to access and visualize SAR data
- Interpretation of SAR images in the context of disaster monitoring
- Interferometric SAR (InSAR) concepts
- Flood mapping and SAR change detection for hazard analysis
- InSAR-based analysis of volcanoes and landslides
The learned concepts will be put into practice in simulated disaster response exercises, in which participants will... read more
GeoEarth-2020 welcomes colleagues from all branches of Geosciences and from many countries in the world to participate to the second edition of thw 'World Congress on Geology and Earth Science'. The Conference will enable the sharing of best practices in Geoscience as well as exploring the role of remote sensing in monitoring Earth processes and dynamics.
The topics of the Conference include:
- Environmental Geology,
- GIS, Remote Sensing and Geospatial Sciences,
- Marine Geosciences and Oceanography,
- Groundwater and Hydrology: Surface Hydrology/Surface Water,
- Rock Deformation and Structural Geology,
- Volcanology and Plate Tectonics,
- Earth, Ecology and Ecosystems,
- Soil Science and Conservation of Soil Biodiversity.
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