Scientific investigation has shown that the first volcanic material collected from the surface of the Mar de Las Calmas off La Restinga consists of basalt and trachyte.

Fragments are formed by magma mixing between two materials, one black (basalt) and one white (trachyte), which occurrs at the time of the eruption.

 

Trachyte was only present in the first few eruptions in a ratio of 1 to 10 with respect to the basalt.

 

Some of the samples were sent to Madrid (MNCN, CSIC), Barcelona (ICTJA, CSIC) and the University of Huelva, where they are doing experimental petrology studies to determine the thermodynamic characteristics of eruptive magmas. In addition, samples have also been sent to Washington State University in the United States and to Clermont Ferrand, France, for isotopic analysis.

 

Basalt is the most common magma coming from the El Hierro eruptions, has a 43% SiO 2, reaches a temperature of 1,200 ° C and a density of 2700 kg/m3.

 

Trachyte is a magma with a SiO2 content of 63%, reaches a temperature of 850 ° C and a density of 2,300 kg/m3. Trachyte is not the predominant magma erupted, therefore does not contribute to increasing the explosiveness of it.

 

Both basaltic materials are highly vesicular, which means that both had a high amount of gas in them at the time of eruption, which would explain its explosive (pyroclastic) formation despite the sea ​​water pressure on the mouth of the volcano. However, this type of explosion is normal within the parameters of basaltic eruptions and there is no additional hazard because samples also contain trachytic magma.