Volcanic Eruption

The Operational Land Imager (OLI) on the Landsat 8 satellite acquired this top image of Mount Etna on December 28, 2018. The image highlights the active vent and thermal infrared signature from lava flows, which can be seen near the newly formed fissure on the southeastern side of the volcano. The image was created with data from OLI (bands 4-3-2) and the Thermal Infrared Sensor (TIRS) on Landsat 8. Image: NASA.

Definition

A type of volcanic event near an opening/vent in the Earth’s surface including volcanic eruptions of lava, ash, hot vapour, gas, and pyroclastic material (IRDR Glossary).

The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates. When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone. Not all volcanoes are related to subduction: another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity—or a hotspot—in the middle of a tectonic plate can push up through the crust to form a volcano. Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface (National Geographic).

A volcano is currently active if it is erupting lava, releasing gas or generating seismic activity. An active volcano is labelled dormant if it has not erupted for a long time but could erupt again in the future. When a volcano has been dormant for more than 10 000 years, it is considered extinct. Volcanoes can remain inactive, or dormant, for hundreds or thousands of years before erupting again. During this time, they can become covered by vegetation, making them difficult to identify.

How explosive a volcanic eruption is depends on how easily magma can flow or trap gas. If magma is able to trap a large amount of gas, it can produce explosive eruptions.  (Australian Government).

 

Facts and figures

Over the last 11,500 years, more than 1,500 major eruptions have occurred, with approximately 500 in the Pacific "Ring of Fire" alone (PreventionWeb).

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those—over 10 percent—sit within the boundaries of the United States (National Geographic).

There are different types of eruptive events. We can distinguish between primary and secondary events.

Primary events are:

  • Pyroclastic explosions
  • Hot ash releases
  • Lava flows
  • Gas emissions
  • Glowing avalanches (gas and ash releases)

Secondary events are:

  • Melting ice, snow and rain accompanying eruptions are likely to provoke floods and hot mudflows (or lahars)
  • Hot ash releases can start fires (WHO).

Volcanoes can have many different appearances. The shape of a volcano provides clues to the type and size of eruption that occurred. Eruption types and sizes depend on what the magma is made up of. Three common volcano forms are:

  1. Shield volcano: have a broad, flattened dome-like shape created by layers of hot and runny lava flowing over its surface and cooling.
  2. Composite volcano : also known as stratovolcanoes, they are formed from explosive eruptions. These eruptions create steep sided cones.
  3. Caldera volcano: these volcanoes erupt so explosively that little material builds up near the vent. Eruptions partly or entirely empty the underlying magma chamber which leaves the region around the vent unsupported, causing it to sink or collapse under its own weight. The resulting basin-shaped depression is roughly circular and is usually several kilometres or more in diameter (Australian Government).

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Actualités

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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).

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Most of the volcanic activities are rapidly evolving phenomena, and thus, hard for volcanologists and disaster management agencies to monitor and predict. In the last four decades, however, due to the proliferation of new and innovative instruments and techniques, scientists have made progress in forecasting the timing of many volcanic eruptions. New studies have shown that combining ground-based information, satellite data, and AI technologies facilitates consistent and long-term monitoring of volcanoes... read more

Publishing date: 02/06/2020
Image: GFZ German Research Centre for Geosciences.

On 22 December 2018 a large chunk of the Anak Krakatau volcanic island collapsed into the ocean, causing a tsunami that swept across Indonesia’s Sunda Strait. Because tsunami early warning systems are exclusively equipped to detect tsunamis that are generated by earthquakes, this volcanic collapse-caused tsunami took place without a warning. In the coastal regions of Java and Sumatra, where people were struck off guard, the tsunami killed 400 people and injured many more.

A recent research study published in Nature Communications and led by the German Research Centre for Geosciences (GFZ) has detected deformations in Anak Krakatau leading up to the tsunami that could serve as an... read more

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A photo of Mt. Etna erupting on 30 October 2002, taken by astronauts aboard the International Space Station. Image: NASA Earth Observatory/Earth Sciences and Image Analysis Laboratory at Johnson Space Center.

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A German research team, made up of scientists  from the Technical University of Berlin and the GFZ German Research Centre for Geosciences in Potsdam,... read more

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Événement

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The topics of the Conference include:

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NASA remote sensing and modeling resources are useful for managing a variety of disasters - including earthquakes, tsunamis, volcanoes, floods, landslides, wildfires, and oil spills - particularly in regions with very little in situ data. This webinar covers the fundamentals and techniques of monitoring Tsunamis, Earthquakes and Volcanoes, including pre-eruption monitoring, SAR-VIEWS,... read more

Data Source

Publishing institution: Airbus Defence & Space
OneAtlas is a collaborative environment to easily access very high resolution imagery, perform large-scale image processing, extract industry specific insights and benefit from Airbus assets to develop solutions. The services include infrastructure change detection, vehicle detection & counting and will soon cover aircraft detection and land use change detection as well . Airbus provides the services through a buy-what-you-need option. It is possible to test the functionalities with a 30-days Free Trial.
Publishing institution: National Aeronautics and Space Administration (NASA)
Based on MODIS data, MIROVA detects near real time volcanic hot spots. In order to do so MIROVA analyses the MiddleInfraRed Radiation (MIR) measured over large volcanoes to detect, locate and measure the heat radiation from volcanic activity. This automated thermal monitoring of the most active volcanoes on Earth in near real time provides the user with a quick overview of the latest thermal images which are available for Google Earth overlapping. Additionally, MIROVA provides an updated Volcanic Radiative Power (VRP) time-series in logarithmic and normal scale. MIROVA has been developed as a collaboration between the University of Turin and the University of Florence.

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