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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques
Stromboli - 01.12.2017 / 12:43 - A poor visibility at the summit did not allow a thermometric analysis of the explosive episode - source: LGS

Stromboli - 01.12.2017 / 12:43 - A poor visibility at the summit did not allow a thermometric analysis of the explosive episode - source: LGS

LGS / Laboratorio Geofisica Sperimentale reports an increase in the explosive activity of Stromboli since 1 December.


Its geophysical monitoring network recorded a major explosive event on December 1 at 12:42 GMT, associated with geophysical parameters (seismic, ground deformation, and sound pressure) above the ordinary level of explosive activity.
The infrasonic network provides pressures around 290Pa at 450m distance and locates the explosive sequence in the southwest crater area, accompanied by a strong 3.5μrad soil deformation signal at the Rina Grande OHO tiltmeters. The lack of visibility at the summit did not allow the thermometric analysis of the event. A map of the fallout of tephras on the Sciara del Fuoco has been established.

 

Stromboli - map of tephra fallout following the explosive eruption of 01.12.2017 - doc.LGS

Stromboli - map of tephra fallout following the explosive eruption of 01.12.2017 - doc.LGS

Stromboli - thermal anomalies identified by Mirova / Modis at 05.12.2017 / 5:50

Stromboli - thermal anomalies identified by Mirova / Modis at 05.12.2017 / 5:50

On December 5, frequent explosions were observed, concentrated in the south-west crater, with medium to high infrasonic pressures above 2 bar. The VLP seismic activity has increased over the last 24 hours and is characterized by 22 episodes / hour, of high amplitude. Degassing remains at average and localized at the north-east crater. The MODIS / MIROVA thermal analysis oscillates between 6 and 27 MW (at 21:25 UTC on 03, 12,2017) in agreement with the observed explosive activity.


Source: LGS & MIROVA

Ol Doinyo Lengai - small eruption of natrocarbonatite at the bottom of the crater - photo Matthieu Kervyn / VUB

Ol Doinyo Lengai - small eruption of natrocarbonatite at the bottom of the crater - photo Matthieu Kervyn / VUB

The news of Ol Doinyo Lengai are rare since the deepening of its crater following explosive episodes in 2007-2008.
Matthieu Kervyn, volcanologist at the VUB / Brussels returns from a documentation expedition in the company of the French television. He tweeted a photo of the crater, and reports a small eruption of natrocarbonatite at the bottom of the summit crater.
In the photo, we notice the presence of two vents, the oldest of which built a small hemispherical cone leaning against a wall of the crater.
 
Source: Matthieu Kervyn & Expertisecentrum Wetenschapscommunicatie Brussel van de VUB / Twitter

Seismicity at the Öræfajökull - 04.12.2017 / 13h50 and 05.12.2017 / 15h10 - Doc. IMO
Seismicity at the Öræfajökull - 04.12.2017 / 13h50 and 05.12.2017 / 15h10 - Doc. IMO
Seismicity at the Öræfajökull - 04.12.2017 / 13h50 and 05.12.2017 / 15h10 - Doc. IMO

Seismicity at the Öræfajökull - 04.12.2017 / 13h50 and 05.12.2017 / 15h10 - Doc. IMO

The Öræfajökull, still shaken by a seismic swarm of low intensity but worrying, does not give us much news of a possible activity.
The IMO, which detects and records earthquakes, reports that during the week of November 17 to December 3, 160 earthquakes were recorded, more than three times more than the previous week. The largest magnitude is M3.5.
In the last 48 hours, the IMO records show nine earthquakes of M between 1 and 2, and an earthquake of about M2.
On the summary histograms of the IMO, there is a clear increase in seismic activity in 2017.

Öræfajökull - summary sismicity histograms 2017 - Doc.IMO

Öræfajökull - summary sismicity histograms 2017 - Doc.IMO

Piece of 3,000 years old trunk found at Breiðamerkursandur - photo RUV / Iceland Review

Piece of 3,000 years old trunk found at Breiðamerkursandur - photo RUV / Iceland Review

Information was nevertheless dropped by one of the glaciers emissary of Vatnajökull, the Breiðamerkurjökull ... you do not locate it ?
Its extended glacier front gives birth to two lakes in which it calve icebergs, Breiðarlón and Jökulsárlón.
Three trunks, 3,000 years old, were found a few months ago on the Breiðamerkursandur, the spreading plain of the Breiðamerkurjökull glacier; their analysis reveals the rapid death of these trees, in their 89th year around the year 500 BC, during the formation of glaciers following a climate change.
It was established that at the time of colonization in the 9th century, Iceland was covered with forests, but this discovery suggests to us that 3,000 years ago, the forests were larger and covered even the highlands.
These specimens will be fixed to the wax after examination, then to be shown to the public.


Source: Iceland Review - 04,12,2017

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