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:

Shield volcano: have a broad, flattened dome-like shape created by layers of hot and runny lava flowing over its surface and cooling.
Composite volcano : also known as stratovolcanoes, they are formed from explosive eruptions. These eruptions create steep sided cones.
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).

Further information

COMET Recent Research page

European Commission's Handbook for Volcanic Risk Management

VolFilm

The Telegraph’s Map of World’s Volcanoes

Volcanic eruptions and their repose, unrest, precursors, and timing

UN-SPIDER Regional Support Offices with hazard-specific expertise

Title: Argentina Regional Support Office

Title: Germany Regional Support Office

Title: Greece Regional Support Office

Title: Indonesia Regional Support Office

Related content on the Knowledge Portal

NigeriaSat-1

On 26 September 2003 Nigeria launched its $13 million national satellite NigeriaSat-1 in Plesetsk, Russia under a seven-nation constellation being handled by a Russian firm, Cosmos. Nigeriasat-1 is a low earth orbit micro satellite for disaster monitoring looking spacecraft, 5-year target design life-span orbit 700km. The launching of the National Satellite, which started development in November 2001, had been postponed from July 2003 because the Russian Space Agency had to launch a military satellite during that period. NigeriaSat-1 is one of five satellites which will make up a network called the Disaster Monitoring Constellation. The other partners in the international consortium are UK, China, Algeria, Turkey, Thailand and Vietnam. Each satellite belongs to one country, but they will share information with each other when disaster monitoring is needed. The Disaster Monitoring Constellation satellites, which cost less than $10 million each, are built by a British-based company,…
read more

27/09/2003
UK-DMC-1 / BNSCSat 1

BNSCSat (British National Space Centre Satellite) or UK-DMC 1 is the UK component of DMC. The Disaster Monitoring Constellation (DMC) is an international programme initially proposed in 1996 and led by SSTL (Surrey Satellite Technology Ltd) from the United Kingdom, to construct a network of five affordable Low Earth Orbit (LEO) microsatellites. The objective is to provide a daily global imaging capability at medium resolution (30-40 m), in 3-4 spectral bands, for rapid-response disaster monitoring and mitigation. The Disaster Monitoring Constellation (DMC) is a novel international co-operation in space, led by SSTL bringing together organisations from seven countries: Algeria, China, Nigeria, Thailand, Turkey, the United Kingdom and Vietnam. The DMC Consortium is forming the first-ever microsatellite constellation bringing remarkable Earth observation capabilities both nationally to the individual satellite owners, and internationally to benefit world-wide humanitarian aid…
read more

27/09/2003
SPOT 5

The satellites SPOT 5 (Satellite Probatoire de l'Observation de la Terre) was a third generation of SPOT earth observation satellite operated by Spot Image.
SPOT 5 used the improved SPOT Mk.3 bus design.
The prime imaging instrument was HRG (High Resolution Geometric), which was built by Astrium SAS of Vélizy, France to continue to improve the HRVIR service of SPOT-4. Two HRG instruments are provided in the conventional SPOT-series double-observation configuration, each with a FOV of 4.13º and the same cross-track pointing capabilities of ±27 º as the HRVIR imager on SPOT-4. The observation coverage of each HRG is 60 km in the nadir direction and >80 km in the oblique configuration.
SPOT-5 carries also the HRS (High Resolution Stereoscopic) instrument, which was developed and built by EADS Astrium SAS, sponsored by CNES and SPOT IMAGE. The objective of this instrument is to provide large-area along-track stereoscopic panchromatic imagery…
read more

04/05/2002
Terra

Terra explores the connections between Earth's atmosphere, land, snow and ice, ocean, and energy balance to understand Earth's climate and climate change and to map the impact of human activity and natural disasters on communities and ecosystems. It was launched on 18 December 1999 and has far exceeded its design life, having a strong chance of operating successfullty into the early 2020s.
Terra is in a circular sun-synchronous polar orbit that takes it from north to south (on the daylight side of the Earth) every 99 minutes.
On October 6, 2018 Terra completed 100,000 orbits around Earth.
Approximately the size of a small school bus, the Terra satellite carries five instruments that take coincident measurements of the Earth system.
Instruments:
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER): Creates high resolution images of water, ice, clouds and the land surface using Shortwave Infrared…
read more

18/12/1999
Landsat 7

The government-owned Landsat 7 was successfully launched on April 15, 1999, from the Western Test Range of Vandenberg Air Force Base, California, on a Delta-II expendable launch vehicle. The Earth observing instrument on Landsat 7, the Enhanced Thematic Mapper Plus (ETM+), replicates the capabilities of the highly successful Thematic Mapper instruments on Landsats 4 and 5.
Landsat 7 is the most accurately calibrated Earth-observing satellite, i.e., its measurements are extremely accurate when compared to the same measurements made on the ground. Landsat 7’s sensor has been called “the most stable, best characterized Earth observation instrument ever placed in orbit.” Landsat 7’s rigorous calibration standards have made it the validation choice for many coarse-resolution sensors.
Considered a calibration-triumph, the Landsat 7 mission went flawlessly until May 2003 when a hardware component failure left…
read more

15/04/1999
NOAA-15

NOAA-15 (designated NOAA-K before launch) is one of the NASA-provided TIROS series of weather forecasting satellite run by NOAA. It was launched on May 13, 1998, and is currently operational, in a sun-synchronous orbit, 807 km above the Earth, orbiting every 101 minutes. It hosts the AMSU-A and AMSU-B instruments, the AVHRR and High Resolution Infrared Radiation Sounder (HIRS/3) instruments, as well as a Space Environment Monitor (SEM/2).
Instruments:
AMSU-A (Advanced Microwave Sounding Unit - A)
AMSU-B (Advanced Microwave Sounding Unit - B)
AVHRR/3 (Advanced Very High Resolution Radiometer/3)
HIRS/3 (High Resolution Infra Red Sounder/3)
S&RSAT (Search & Rescue Satellite-Aided Tracking System)
DCS/s (Data Collection System/2)
SEM/MEPED (SEM/Medium energy proton detector)
SEM/…
read more

13/05/1998
SPOT 4

The satellites SPOT 4 (Satellite Probatoire de l'Observation de la Terre) was a second generation of SPOT earth observation satellite operated by Spot Image.
SPOT 4 used the improved bus design, which differed from the earlier SPOT series by having an increased lifetime of five years instead of three, a new extended platform design and service module, which can accommodate twice the payload. The propulsion module consists of a frame made of aluminum bars and two capillary tanks holding 158 kg of hydrazine.
The prime imaging instrument was HRVIR (High-Resolution Visible and Infrared sensor), which consisted of two pushbroom imaging units, an improved version of HRV. The two spectral modes are panchromatic and multispectral. The panchromatic band had a resolution of 10 meters, and the three multispectral bands (G,R,NIR) have resolutions of 20 meters.
An additional sensor for SPOT-4, called Vegetation or VMI (Vegetation Monitoring Instrument), with a ground swath…
read more

24/03/1998
SPOT 3

The satellites SPOT 1, 2 and 3 (Satellite Probatoire de l'Observation de la Terre) were the first generation of SPOT earth observation satellites operated by Spot Image.
The first generation SPOT satellites were built on the SPOT Mk.1 bus with a lifetime of three years.
The SPOT satellites were identical, with each carrying two identical HRV (High Resolution Visible) imaging instruments that were able to operate in two modes, either simultaneously or individually. The two spectral modes are panchromatic and multispectral. The panchromatic band had a resolution of 10 meters, and the three multispectral bands (G,R,NIR) have resolutions of 20 meters.
SPOT 3 was orbited on 26 September 1993 on an Ariane-40 H10 rocket. It ended operations in November 1996 due to problems with its stabilization system.
Instruments: 2 HRVs
- 4 spectral bands (1 panchromatic, 3 multispectral)
- imaging swath: 60km x 60km to 80km
read more

26/09/1993
SPOT 2

The satellites SPOT 1, 2 and 3 (Satellite Probatoire de l'Observation de la Terre) were the first generation of SPOT earth observation satellites operated by Spot Image.
The first generation SPOT satellites were built on the SPOT Mk.1 bus with a lifetime of three years.
The SPOT satellites were identical, with each carrying two identical HRV (High Resolution Visible) imaging instruments that were able to operate in two modes, either simultaneously or individually. The two spectral modes are panchromatic and multispectral. The panchromatic band had a resolution of 10 meters, and the three multispectral bands (G,R,NIR) have resolutions of 20 meters.
SPOT-2 was launched on 22 January 1990, on an Ariane-40 H10 rocket. It operated until July 2009. Its orbit was lowered to ensure reentry within 25 years.
Instruments: 2 HRVs
- 4 spectral bands (1 panchromatic, 3 multispectral)
- imaging swath: 60km x 60km to 80km
read more

22/01/1990
SPOT 1

The satellites SPOT 1, 2 and 3 (Satellite Probatoire de l'Observation de la Terre) were the first generation of SPOT earth observation satellites operated by Spot Image.
The first generation SPOT satellites were built on the SPOT Mk.1 bus with a lifetime of three years.
The SPOT satellites were identical, with each carrying two identical HRV (High Resolution Visible) imaging instruments that were able to operate in two modes, either simultaneously or individually. The two spectral modes are panchromatic and multispectral. The panchromatic band had a resolution of 10 meters, and the three multispectral bands (G,R,NIR) have resolutions of 20 meters.
SPOT 1 was launched with the last Ariane-1 rocket on 22 February 1986. At the end of operations in 2003, the orbit was lowered to gradually lose altitude until reentry.
Instruments: 2 HRVs
- 4 spectral bands (1 panchromatic, 3 multispectral)
- imaging swath: 60km x 60km to 80km
read more

22/02/1986