Earthquake

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.

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.
 

Related content

News

This map shows the ground motion during the six months following the earthquake that struck the Indonesian Island of Sulawesi on 28 September 2018, and was obtained by processing Copernicus Sentinel-1 images acquired between October 2018 and April 2019. Image: ESA/contains Copernicus Sentinel data (2018–19), processed by Planetek Rheticus Service.

In September 2018, the Indonesian island of Sulawesi was hit by a 7.5 magnitude earthquake. The impact, combined with the tsunami, landslides, and soil liquefaction that followed, “... claimed well over 2000 lives, destroyed homes, buildings, infrastructure and farmland in several districts,” according to the European Space Agency (ESA)

Ten months later, response efforts are now moving into the... read more

Publishing date: 06/08/2019
Damage from a 7.4 earthquake and a tsunami that hit the Indonesian island of Sulawesi on 28 September 2018. Image: European Union/Pierre Prakash/Flickr.

In the past year, “there were 315 natural disaster events recorded with 11,804 deaths, over 68 million people affected, and US$131.7 billion in economic losses around the world.” This is according to the Centre for Research on the Epidemiology of Disasters (CRED) in its recently released 2018 Natural Disasters Report

While these 2018 natural disaster values represent a decrease when compared with the annual averages from 2008 to 2017, some geographic areas still experienced great losses of life and damages due to natural hazards. Indonesia was most adversely impacted in terms of lives... read more

Publishing date: 01/07/2019

As part of it advisory support activities, UN-SPIDER is carrying out out a Technical Advisory Mission (TAM) to Peru from 1 to 5 April to evaluate the current and potential use of space-based information in all aspects of disaster management. Based on exchanges with a wide range of stakeholders, UN-SPIDER will provide recommendations as to how to strengthen the use of space-based information in disaster risk management and emergency response in the country.

The team of experts led by UN-SPIDER is conducting multiple activities and institutional visits in Lima. The team is comprised of eight experts from UN-SPIDER; the German Aerospace Centre (... read more

Publishing date: 01/04/2019
This image captured by the Copernicus Sentinel-2A satellite on 28 December 2015. It demonstrates Nepal’s varied terrain from the mountains to the north (left side) to the plains in the south (right side). Vegetation appears red in this false-colour image, while waterways and buildings appear light green and blue. Image: ESA.

On 12 March, Nepal Telecommunications Authority (NTA) signed an agreement with French satellite operator Thales Alenia Space to build Nepal’s first communications satellite. The Nepalese government intends to use the satellite to provide nationwide internet access to its citizens, improve disaster management efforts and strengthen economic growth in the country.

The development of Nepal’s own satellite system proves to be significant in terms of improving the country’s disaster management efforts. Nepal... read more

Publishing date: 29/03/2019
Participants are being trained in analyzing maps produced as part of International Charter activations.

As part of the technical advisory support it provides to countries worldwide, UN-SPIDER carried out an Institutional Strengthening Mission to Myanmar from 11 to 15 March 2019 upon the request of the government. This activity was jointly organized by UN-SPIDER and the United Nations Human Settlement Programme (UN-Habitat), under auspices of the Ministry of Social Welfare, Relief and Resettle­ment (MSWRR) of Myanmar. It was hosted by the Emergency Operation Centre (EOC). Experts from the Centre for Space Science and Technology Education in Asia and the Pacific (CSSTEAP), the... read more

Publishing date: 19/03/2019
Synthetic aperature radar patterns of seismic deformations associated with a model earthquake on the San Francisco section of the San Andreas Fault.

Earthquakes are a major concern in increasingly populated regions, however their prediction is a difficult task. Researchers have recently made progress in the use of complex simulation and modeling techniques to better forecast the occurrences of earthquakes.

In a recent study, researchers used Gradient Boosted Regression Trees, a machine learning technique for regression and classification problems that incorporates training data, to better determine spatiotemporally complex loading histories within subduction zones. The researchers simulated tens of earthquakes using a small‐scale experimental replica of a subduction zone and show that machine learning predicts well the timing and size of laboratory... read more

Publishing date: 13/03/2019

Data Source

Publishing institution: Canadian Space Agency (CSA)
Publishing institution: United States Geological Survey (USGS)
Compiled Vs30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and other governmental agencies. Thus far, there are 2,997 sites in the United States, along with metadata for each measurement from government-sponsored reports, Web sites, and scientific and engineering journals. Most of the data originated from publications directly reporting the work of field investigators. A small subset (less than 20 percent) of Vs30 values was previously compiled by the USGS and other research institutions. Whenever possible, Vs30 originating from these earlier compilations were crosschecked against published reports. Both downhole and surface-based Vs30 estimates are represented. Most of the VS30 data are for sites in the western contiguous United States (2,141 sites), whereas 786 Vs30 values are for sites in the Central and Eastern United States; 70 values are for sites in other parts of the United States, including Alaska (15 sites), Hawaii (30 sites), and Puerto...

GP-STAR factsheet

Schematic Workflow for the derivation of an exemplary Sendai indicator using crisis information generated from satellite remote sensing (Source: own figure; Copernicus Emergency Management Service (©European Union), EMSN024, EMSN056)
Publishing institution: German Federal Office of Civil Protection and Disaster Assistance

To meet the global challenges, the United Nations adopted several framework agreements, including the Sendai Framework for Disaster Risk Reduction at the Third United Nations World Conference on Disaster Risk Reduction (2015-2030). The framework builds the international reference point for disaster preparedness and focuses on... read more

Event

In the intermediate webinar Remote Sensing for Disasters, participants learn the usage of NASA products to monitor three kinds of disasters. The webinar takes place in three sessions on each Tuesday from 16 until 30 April 2019, starting 10 to 12 am and 2 to 4 pm. It is taught in English and Spanish and is free of charge.

Learning Objectives

By the end of this training, attendees will be able to:

  • Identify NASA data products to characterize and monitor the disasters, Tropical Storms, Flooding, Landslides and Earthquakes, and support decision-making

  • Understand the different data products available and... read more

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