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 on the Knowledge Portal

Noticias

Logo of the International Charter "Space and Major Disasters"

The International Charter “Space and Major Disasters” has been activated on 6 August after a 6.9 magnitude earthquake struck the island of Lombok, Indonesia.

At least 98 people have been killed and 10,000 have been evacuated after a 6.9 magnitude earthquake struck off the coast of Lombok, destroying buildings and cutting power. The neighbouring islands of Bali and Gili Islands have also been affected. The quake struck at a depth of 13 km, according to GEOFON Program Potsdam, and tsunami warnings were triggered. Search and rescue efforts are also being affected by dangerous aftershocks, with over 130 having been recorded since the initial earthquake.

The International Charter activation was requested by the Asian Disaster... read more

Publishing date: 07/08/2018
Lava flows erupting from a fissure on 5/5/18. Image: US Geological Survey.

The International Charter Space and Major Disasters has been activated for an earthquake and eruption of the Kilauea Volcano in Hawaii, USA on Monday.

The volcano erupted on 4 May alongside a 6.9 magnitude earthquake, spraying lava up to 70 metres and causing the evacuation of 2000 individuals, in addition to the destruction of several buildings. Dangerous levels of toxic sulfur dioxide from the lava flows also present a... read more

Publishing date: 11/05/2018
Collapsed Santa Monica Freeway bridge across La Cienega Boulevard, Los Angeles after the Northridge earthquake, Jan. 17, 1994. Image: Robert A. Eplett/FEMA

Global Navigation Satellite Systems (GNSS) are giving scientists in North America new insights into detecting potential earthquakes before they strike.  

Accurate early warning of earthquakes is challenging because of earthquakes’ unpredictable nature. They often strike on otherwise normal days and frequently strike with fatal force. In spite of recent advances in seismology, the prediction of earthquakes remains difficult.

However Global Positioning System... read more

Publishing date: 09/05/2018

Data Source

Publishing institution: VITO
The Proba-Vegetation mission provides information on vegetation, including crop yield and drought, based on PROBA-V and Sentinel-3 data.

UN-SPIDER Training Activity

Post-Disaster (Earthquake) Rapid Damage Assessment | Date of training: 28/03/2017 to 02/04/2017
International Training Course on Integration of Multisource Earth Observation Data for Disaster Damage Assessment | Date of training: 25/10/2017 to 31/10/2017

Pages

Hazard group

Terms in the same hazard group

Zircon - This is a contributing Drupal Theme
Design by WeebPal.