The mortal Indonesian tsunami last October makes the work topical A new scenario for the mass transport deposits west Canary volcanic province published by researchers from the Geological and Mining Institute of Spain (IGME) and the Spanish Institute of Oceanography (IEO) in the scientific journal Earth and Planetary Science Letters (EPSL).
From the IGME detailed this Friday that the article establishes for the first time the beginning of the gravitational dismantling of the Islands by its west side approximately 13.5 million years ago (with a margin of error of 1.2, Miocene medium-superior) and reveals an enormous system of flow of sludge sediments (mass transport depots, in English mass transport deposits, MTDs) from the Archipelago of 850 kilometers wide and 750 kilometers long, one of the largest on the planet.
The start of the gravitational dismantling of the volcanic province of the Canary Islands coincides with one of the episodes of maximum volcanic activity in the archipelago (Middle-Upper Miocene), added the same sources in a press release before underlining that it is the first time that is evident this fact in the submarine bottom at the foot of the Islands and corroborates the relationship "volcanic activity-submarine landslides" that had been inferred from the turbiditic sediments in the abyssal plain of Madeira, as final products generated from these large avalanches.
In the opinion of the IGME, the impact of the work published in EPSL in the scientific community resides in the application of this scenario and sedimentary model in other volcanic oceanic islands of the planet.
On the other hand, the article also reveals for the first time that these Avalanche processes do not only take place on the flanks of the volcanic islands, but can also affect seamounts also of volcanic origin.
It is the case of seamounts to the southwest of the Canary Islands, which give rise to the formation of MTDs, in their great majority buried and hitherto unknown, which constitute the southernmost branch of this sludge flow system coming from the volcanic province.
Another finding is that these MTDs located at the foot of the seamounts south of the Canary Islands would indicate a possible volcanic (or tectonic) reactivation from the Miocene period to the Quaternary against what was thought until now, that is to say, that they were inactive from the Upper Cretaceous (from 100-80 million years ago).
The article concludes that this system of MTDs from the landslides of the volcanic province of the Canary Islands has remained active, intermittently, from mid-upper Miocene to the Quaternary and coinciding with the episodes of volcanic activity in the Canary Islands.
The processes of construction (eruptions) and destruction (landslides) of oceanic volcanic islands are intimately linked and are inherent in its geological evolution, explained from the state scientific institution.
Precisely, the landslides of volcanic oceanic islands, also called flank collapses, are the most important mass transport geological processes on the planet, reaching some more than 5,000 cubic kilometers as in the case of the Hawaiian Islands, a volume equivalent to almost five million football stadiums like the Metropolitan Wanda (1 stadium = 1 million cubic meters).
In the case of the Canary Islands, where these processes have been widely studied by the international scientific community, the The most modern dated slip is that of El Golfo (23.5-82.5 thousand years ago), That made disappear approximately 40% of the emerged surface of the island of El Hierro.
Controversy about tsunamis
But nevertheless, its tsunamigenic power is very controversial since, although these processes mobilize a significant volume of rocks, the wave that would generate would not be as huge as one might think, nuanced from the IGME.
Precisely, this article detects for the first time in the sediments at the foot of the Canary Islands that these flank collapses are not normally produced as a single event and isolated in time by mobilizing huge amounts of rock, if not produced in a multi-episodic way, that is, through several sliding processes and dilated in time.
However, although some of them manage to generate a devastating tsunami as in the recent event in Indonesia; others, fortunately they are as small as the one that happened on the volcanic cone of Tagoro during the eruption of the Restinga in 2011 from which no consequence was detected.
In the opinion of the IGME, much remains to be discovered and researched on these unknown geological processess, mechanisms of breakage, dynamics and their role in the transfer of sediments from the oceanic islands to the abyssal plains, which, as in the case of the Canary Islands, cover almost 750 kilometers.
It also forces review and update security alert systems As the Protocol of notices on phenomena susceptible to generate tsunamis, which does not consider volcanic activity as a potentially tsunamigenic phenomenon, in addition to the absence of warning systems for its prevention, concluded from the Geological and Mining Institute of Spain.