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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, #Volcans et climat

Volcanoes can have an impact on the climate, it is proved, but can the climate influence volcanic activity?

The white line represents the present Mediterranean coastline, the blue regions show the underwater zone in the event of a 2 km lowering of the Mediterranean sea level as proposed during the Messinian salinity crisis and the circles reds show the location of the volcanic provinces whose activity was increased during Messinian (the size of the circle is proportional to the increase in activity). © UNIGE

The white line represents the present Mediterranean coastline, the blue regions show the underwater zone in the event of a 2 km lowering of the Mediterranean sea level as proposed during the Messinian salinity crisis and the circles reds show the location of the volcanic provinces whose activity was increased during Messinian (the size of the circle is proportional to the increase in activity). © UNIGE

An inter-university team, under the direction of the University of Geneva, analyzed the period of the Messinian salinity crisis, between 5.96 and 5.33 million years ago, when the Mediterranean was isolated from the Atlantic, following the closure of the Strait of Gibraltar, and dried up.
Since the late 1970s, important layers of salts have been found on the Mediterranean Sea, suggesting an interruption or a severe decrease in communication between the seas. Deep underwater canyons were discovered, dating back to the same period, left by rivers flowing over land now submerged ... which includes a lower sea level than at present.
It was also established that activity in various volcanic provinces around the Mediterranean was important during the same period: during the Messinian salinity crisis, there were 13 eruptions, which is more than twice the average ratio of activity outside the Mediterranean sea of this period (equal to 4.5 eruptions)

Palaeogeography in the Messinian - From Jolivet 2007 - Doc. in The lithotheque Aix Marseille

Palaeogeography in the Messinian - From Jolivet 2007 - Doc. in The lithotheque Aix Marseille

"The simulations made during the study show that the only way to account for the increase in volcanic activity was that the level of the Mediterranean Sea (and therefore its weight) had decreased by about two kilometers" explains Pietro Sternai of the UNIGE.
The study shows the impact of surface processes, largely controlled by climate, on the depths of the earth's layers, and its influence on magmatic production, due to deep pressure changes.
"This pioneering work opens up new possibilities for interdisciplinary studies on the coupling between solid and fluid Earth and involves, for example, volcanologists, geomorphologists and climatologists" concludes Sternai.
 
Sources:
- University of Geneva - Climate change can goad volcanoes into life - link
- Nature Geoscience (1977) doi: 10.1038 / link - link
- Messinian salinity crisis regulated by competing tectonics and erosion at the Gibraltar arch - by D.Garcia-Castellanos & al / Nature 480

 

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