Volcanic Eruption

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).

UN-SPIDER Regional Support Offices with hazard-specific expertise

Related content on the Knowledge Portal

  • Volcanic eruptions, as one of Earth’s most dramatic and violent agents of change, can drastically alter land and water for kilometres around a volcano. 99 % of the gas molecules emitted in a volcanic eruption are water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). The remaining 1 % comprises small amounts of hydrogen sulfide, carbon monoxide, hydrogen chloride, hydrogen fluoride, and other minor gas species (USGS).

    This webinar will focus on the exploitation of Sentinel-5P data to map the SO2 concentrations originated on the occasion of a volcanic eruption in the Volcan de Fuego, Guatemala.

    To implement this analysis, participants will be using Python code run in a Jupyter…

    read more
  • Monitoring deformation in active volcanic areas has always been of great interest, but remote sensing data has significantly increased the capability of acquiring more measurements at larger spatial scale and at relatively low cost.

    Stromboli, one of the three active volcanoes in Italy, is around 3 km high with at least 2 km to be below the sea level and showing an eruptive persistent activity since almost 200,000 years. As a stratovolcano, the relatively high pressure of the gases ejects basaltic lava and its products from a few tens to hundreds of meters into the air. Many significant explosions and lava flows have been recorded in the last 50 years, the most recent events occurring on November 10 and 16, 2020. From the last one, a dense ash cloud was produced around 1 km high above the volcano’s summit and the pyroclastic current reached rapidly the coastline, expanding on the sea surface for about 200 m.

    In this…

    read more
  • Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
  • Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
  • The European Space Agency is organising the 11th International Workshop on “Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR”, Fringe 2021.

    Format

    Fringe 2021 is organised around:

    • Papers and e-posters selected by the Scientific Committee;
    • Invited papers on ESA-funded studies and Sentinel-1 and future ESA SAR mission status reports;
    • Round-table discussions with seed questions prepared by the session chairpersons and ESA.

    The event will take place from 31 May - June 4 2021. No participation fees will be charged.

    Objectives

    • To bring together the global InSAR research and development communities and facilitate international exchange between researchers and research groups; 
    • To present the Sentinel-1 mission status, algorithms and products;
    • To review and assess the progress according to the…
    read more
  • In recent years, the frequency and severity of natural hazards has increased dramatically. This development has escalated the risk of disasters and their devastating impact on the environment and communities around the world. Earth observation (EO) data has the potential to mitigate the risks of disasters and support all phases of the disaster management cycle. The international community has created various mechanisms to facilitate the use of EO data for disaster management, such as the International Charter Space and Major Disasters. The Algerian Space Agency (ASAL) has provided EO data to the International Charter for almost two decades.

    The International Charter refers to a consortium of space agencies, national and regional disaster monitoring organizations that utilize EO data for…

    read more
    Regional Support Offices mentioned:
    13/04/2021
  • The United Nations Office for Outer Space Affairs (UNOOSA) and the National Aeronautics and Space Administration of the United States Government (NASA) signed a landmark Memorandum of Understanding (MoU) on 17 December 2020 pledging cooperation in areas of science and technology to support the peaceful uses of outer space.

    The MoU brings together NASA's wealth of open-source spacecraft data, tools, and expertise and UNOOSA's unique position as the only UN entity dedicated to outer space affairs, to expand global opportunities to leverage the benefits of space. The partners will design capacity-building programmes, particularly for institutions in countries that do not yet have or that are developing space capabilities, to help them access space.

    Together, UNOOSA and NASA will develop ways to leverage the Artemis programme as part of UNOOSA's Access to Space 4 All Initiative, which offers opportunities for international researchers and institutions, especially in…

    read more
    11/01/2021
  • Recently, two volcanoes in the Caribbean indicated increased activity: Mount Pelée on Martinique and the La Soufrière volcano on Saint Vincent and the Grenadines. Mount Pelée has been experiencing seismic activity and the La Soufrière volcano has been releasing gas. In light of this increased activity and the risk that a potential volcanic eruption poses to the environment and human life, a programme at the National Aeronautics and Space Administration (NASA) was activated earlier this year to monitor the region.

    A volcanic eruption can have a highly destructive impact on the environment and human life. For this reason, satellite-based radar instruments can be used to monitor volcanic activity and support disaster management efforts. Following an increased activity manifested by these two volcanoes in the Caribbean, the Earth Applied Sciences Disasters programme at NASA is actively monitoring the region and analysing Earth observation (EO) data to monitor this volcanic…

    read more
    10/03/2021
  • The European Commission plans to rapidly expand its environmental monitoring programme Copernicus. For this purpose, the European Space Agency (ESA) recently pledged 2.55 billion Euros towards contracts to advance the production of six new Copernicus satellite missions. The final of the six contracts was signed last Thursday between ESA and Thales Alenia Space for a mission that will provide new and important information to climate research and disaster management.

    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, an…

    read more
    18/12/2020
  • The Disasters programme unit at the National Aeronautics and Space Administration (NASA) recently joined a newly launched online platform aimed at placing anticipatory action on the humanitarian agenda. NASA’s involvement in the Anticipation Hub and the subsequent incorporation of Earth observation (EO) tools, serves to improve the capabilities of anticipatory action globally and demonstrates the potential of utilizing satellite-driven data for anticipatory action in disaster management.

    Anticipatory action in the humanitarian context describes disaster mitigation activities based on in-depth forecast information and risk analysis. This approach has gained traction amongst the humanitarian community in recent years as it is viewed as a more efficient and affordable alternative to…

    read more
    02/02/2021

Term Parents

UN-SPIDER Regional Support Offices with hazard-specific expertise