Tag Archives: volcanic gas

Researchers track sneaky Eastern Rift emissions

24th October 2017 COMET2014

COMET researchers at the University of Oxford have estimated the total carbon emissions emanating from the Eastern Rift – the eastern branch of the East African Rift, a zone near the horn of East Africa where the crust stretches and splits.

A hot spring bubbling with carbon dioxide in Ethiopia near the Main Ethiopian Rift. Credit: Jonathan Hunt

The new study published in Geochemistry, Geophysics, Geosystems, led by COMET PhD student Jonathan Hunt, working alongside Tamsin Mather and David Pyle as well as colleagues from Oxford and Addis Ababa University, Ethiopia, extrapolates from soil carbon dioxide surveys to estimate that the Eastern Rift emits somewhere between 3.9 and 32.7 million metric tons (Mt) of carbon dioxide each year.

The research demonstrates how, even near some seemingly inactive volcanoes, carbon dioxide from melted rock seeps out through cracks in the surrounding crust.

You can read more about the study on the Deep Carbon Observatory website.

The full reference is: Hunt JA, Zafu A, Mather TA, Pyle DM, Barry PH (2017) Spatially variable CO₂ degassing in the Main Ethiopian Rift: Implications for magma storage, volatile transport and rift-related emissions. Geochemistry, Geophysics, Geosystems doi: 10.1002/2017GC006975

Volcanoes

Coupling volcanic gas emission measurements to computational models of conduit gas flow

25th May 2016 COMET2014

A new paper published in Geophysical Research Letters by Tom Pering and Andrew McGonigle has combined fluid dynamical modelling of gas flow in conduits with high time resolution measurements of volcanic gas discharge for the first time, revealing new insights into the dynamics of Stromboli volcano.

Their work is based on a recently developed approach using ultraviolet cameras which enable measurements of volcanic gas emission rates with unprecedented time resolution – around 1 Hz – such that gas release patterns associated with rapid explosive and non-explosive basaltic processes, can be resolved for the first time.

Data were captured on Stromboli, where an intriguing coda of lifetime on the order of 10s of seconds was identified following each explosion. Computational models were also developed to simulate the upward flow of conduit filling, so called “Taylor bubbles”, which are believed to be responsible for explosions on Stromboli when they burst at the surface.

The numerical models reveal the fissioning of smaller bubbles from the Taylor bubble bases to generate a train of “daughter bubbles”, thought to be responsible for generating the post-explosive coda upon arrival at the surface.

This process could play a primary yet hitherto unconsidered role in driving the dynamics of strombolian volcanism, both on Stromboli and other targets worldwide, with significant implications for the magnitude of resulting eruptions.

Combining models with field observations in this way shows considerable promise for improving our understanding of how gases drive volcanic activity.

The full reference is: T.D Pering, A. J. S McGonigle, M. R James, G. Tamburello, A. Aiuppa, D. Delle Donne, M. Ripepe Conduit dynamics and post-explosion degassing on Stromboli: a combined UV camera and numerical modelling treatment, Geophysical Research Letters 2016 DOI: 10.1002/2016GL069001

Volcanoes

Tracking the Etna eruption

7th December 2015 COMET2014

On the evening of December 2 2015, Sicily’s Mount Etna began to erupt for the first time in over two years, reaching a brief but violent climax in the early hours of December 3 which included lava fountains as well as a column of gas and ash several kilometres high. The event was among the most violent seen at Etna over the last twenty years.

Ash cloud from Mount Etna’s Voragine crater lights up the sky. Credit: Marco Restivo/Demotix/Corbis

Luckily, good weather meant that the eruption could be monitored with visual and thermal cameras from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) Etna Observatory. According to INGV reports, activity peaked between 02:20 and 03:10 GMT when a continuous lava fountain reached heights well above 1km; with some jets of volcanic material reaching 3km into the sky. Although the eruption had more or less ceased by dawn, the volcanic cloud had blown northeast, causing ash to be deposited on the nearby towns of Taormina, Milazzo, Messina and Reggio Calabria.

The eruption has so far continued, repeating the behaviour seen earlier with tall lava fountains and eruption columns many kilometers high. Updates can be found on the INGV webpage.

COMET scientists at the University of Oxford have been tracking the volcanic plume’s progress using data from the Infrared Atmospheric Sounding Instruments (IASI) on board ESA’s MetOp-A and MetOp-B satellite platforms. These instruments can detect the presence of volcanic SO₂ in the atmosphere, using methods developed by the University’s Earth Observation Data Group.

The results, which can be found on the IASI NRT web page, showed that by Friday 4 December the plume had reached an area between Crete and Iraq, containing 0.06 Tg (10¹²g) SO₂.

Estimate of SO2 amount from IASI-A overpass on the morning of 3 and 4 December 2015, assuming the SO2 between 9 and 10 km altitude

By the morning of 7 December, the plume had travelled from Sicily to Asia, reaching as far as Japan and the Pacific Ocean.

Screenshot from IASI NRT webpage 7 December 2015

Dr Elisa Carboni, a COMET researcher based at the University of Oxford, said: “This is a great example of how we can track volcanic plume using the near real time IASI service. ”

You can follow the volcanic plume on the IASI NRT web page.

Volcanoes

COMET scientists analyse Calbuco eruption

5th May 2015 COMET2014

On 22^nd April Calbuco volcano, Chile, erupted for the first time since 1972 with very little warning. Plumes of volcanic ash reached heights of 16 km on the 22^nd and up to 17 km in a second, longer eruption that began in the early hours of 23^rd April.

Several thousand people were evacuated from villages closest to Calbuco , and ash fell over an area extending from the west coast of Chile to the east coast of Argentina, and grounded air traffic in Chile, Uruguay and Argentina.

COMET scientists have been using satellite data to analyse the event, in terms of both the emissions and changes to the shape of the volcano itself. You can read more about the event here.

Figure 4. Data, spherical source elastic half space model and residuals for recent deformation at Calbuco [Bagnardi]. — Data, spherical source elastic half space model and residuals for recent deformation at Calbuco [Bagnardi].