Introducing Marsili SeaMount

[BrickFielder]

Introduction
My intention is to produce a series of articles (depending on interest) which introduces ideas about volcanic and earthquake activity. I want to go slightly off the beaten track to explore oddities, volcano hazards, analysis methods, Wonders and Mankind’s impacts. Keep in mind I am not expert (corrections gratefully received), but hopefully these will at least give a flavour of some different places in the world and provide a few minutes escape from people’s troubles.

Introducing Volcano Marsili SeaMount

 

The Reason for Interest
When we think about very large volcanoes in Europe we tend to think of Mount Etna yet there are some even larger little known submerged volcanoes. If one of those Volcanoes is a rather crumbling volcano which could have a flank collapse and produce a tsunami in the Mediterranean then this elevates the volcano to a more interesting one. This will be a slightly shorter post due to limited information being available.

The Setting
 The African plate is on a collision course with the European Plate creating a subduction zone in the western Mediterranean. Over time Africa has moved so far north that almost all of the heavier oceanic crust between the continents has been subducted underneath the European plate. With Africa’s continental crust just not being heavy enough to subduct anymore the subduction has slowed and in some areas reversed.

What we are left with at present is a result of very complex subduction systems and rifting processes. In the SE part of the Tyrrhenian Sea the bending and stretching crust produced several basins. The rapid sinking of the Marsili Basin due to stretching was accompanied by rigorous magmatic activity from numerous volcanoes. In the Marsili basin reside at least two active submarine volcanoes the Marsili and Palinuro Seamounts. The older Palinuro Seamounts topology in its western part suggests a caldera-forming gravitational collapse event of the edifice has occurred. 

The Volcano
This seamount was discovered during the 1920s and named after an Italian geologist, Luigi Ferdinando Marsili. Extensive studies have been carried out since 2005 when the Italian National Research Council started a vulcanology research program on the site. It is the largest volcanic edifice in the Tyrrhenian Sea, and it can also be ranked as the largest in Europe. The huge massif is about 55 km long and 30 km wide. The foot of the volcano is at a depth of 3000 m and it rises to some 500 m below the water surface. Marsili formed by passive magma ascent along existing fractures caused by early spreading activity. Analyses of Marsili basalts suggest the presence of a still active magma reservoir roughly 2.5 km below the summit of the volcano. Various seismographs positioned on the volcano have detected continuous shallow volcano-tectonic seismic activity.

Recent Activity
The most recent known eruptions of Marsili date back to an age between 7,000 and 2,000 years ago. These were events with a low VEI, occurring particularly in the central sector of the massif between 800 and 1000 m of depth. In the case of a submarine eruption at depths of 500-1000 meters, the only signs on the surface would be pumice floaters, a colored stain and spots of boiling water due to degassing. 

Discussion
 The volcano is mechanically stabilized by a series of fractures filled with compact lava rock forming containment walls. Research vessels found evidence of many small, localized landslide scars along its flanks. Such landslides reducing the flanks are very common in submarine structures but might have reduced the thickness of those containing walls. It is thought that an inflation from the ascent of a quantity of magma could seriously destabilize whole sectors of the volcano. Tsunamis, caused by submarine landslides could extend to all the Tyrrhenian coasts including the shores of Campania, Calabria and Sicily. Evidence suggests that similar Tsunamis have happened several times in the past.  Whilst the threat is clear we should be careful not to over emphasize it.

 

 

 

[Snipper]

7 minutes ago, BrickFielder said:

Introduction
My intention is to produce a series of articles (depending on interest) which introduces ideas about volcanic and earthquake activity. I want to go slightly off the beaten track to explore oddities, volcano hazards, analysis methods, Wonders and Mankind’s impacts. Keep in mind I am not expert (corrections gratefully received), but hopefully these will at least give a flavour of some different places in the world and provide a few minutes escape from people’s troubles.

Introducing Volcano Marsili SeaMount

 

The Reason for Interest
When we think about very large volcanoes in Europe we tend to think of Mount Etna yet there are some even larger little known submerged volcanoes. If one of those Volcanoes is a rather crumbling volcano which could have a flank collapse and produce a tsunami in the Mediterranean then this elevates the volcano to a more interesting one. This will be a slightly shorter post due to limited information being available.

The Setting
 The African plate is on a collision course with the European Plate creating a subduction zone in the western Mediterranean. Over time Africa has moved so far north that almost all of the heavier oceanic crust between the continents has been subducted underneath the European plate. With Africa’s continental crust just not being heavy enough to subduct anymore the subduction has slowed and in some areas reversed.

What we are left with at present is a result of very complex subduction systems and rifting processes. In the SE part of the Tyrrhenian Sea the bending and stretching crust produced several basins. The rapid sinking of the Marsili Basin due to stretching was accompanied by rigorous magmatic activity from numerous volcanoes. In the Marsili basin reside at least two active submarine volcanoes the Marsili and Palinuro Seamounts. The older Palinuro Seamounts topology in its western part suggests a caldera-forming gravitational collapse event of the edifice has occurred. 

The Volcano
This seamount was discovered during the 1920s and named after an Italian geologist, Luigi Ferdinando Marsili. Extensive studies have been carried out since 2005 when the Italian National Research Council started a vulcanology research program on the site. It is the largest volcanic edifice in the Tyrrhenian Sea, and it can also be ranked as the largest in Europe. The huge massif is about 55 km long and 30 km wide. The foot of the volcano is at a depth of 3000 m and it rises to some 500 m below the water surface. Marsili formed by passive magma ascent along existing fractures caused by early spreading activity. Analyses of Marsili basalts suggest the presence of a still active magma reservoir roughly 2.5 km below the summit of the volcano. Various seismographs positioned on the volcano have detected continuous shallow volcano-tectonic seismic activity.

Recent Activity
The most recent known eruptions of Marsili date back to an age between 7,000 and 2,000 years ago. These were events with a low VEI, occurring particularly in the central sector of the massif between 800 and 1000 m of depth. In the case of a submarine eruption at depths of 500-1000 meters, the only signs on the surface would be pumice floaters, a colored stain and spots of boiling water due to degassing. 

Discussion
 The volcano is mechanically stabilized by a series of fractures filled with compact lava rock forming containment walls. Research vessels found evidence of many small, localized landslide scars along its flanks. Such landslides reducing the flanks are very common in submarine structures but might have reduced the thickness of those containing walls. It is thought that an inflation from the ascent of a quantity of magma could seriously destabilize whole sectors of the volcano. Tsunamis, caused by submarine landslides could extend to all the Tyrrhenian coasts including the shores of Campania, Calabria and Sicily. Evidence suggests that similar Tsunamis have happened several times in the past.  Whilst the threat is clear we should be careful not to over emphasize it.

 

 

 

All good by me. Amazing what is going on there.