Sea stain caused by the underwater volcanic eruption off the coast of the island of El Hierro has grown to almost half the size as the island itself, according to the latest satellite photos. The green stain, visible on the surface of the sea, was caused by sulfur expelled by the underwater volcano, which began to erupt on Thursday after several weeks of seismic activities. Spanish government scientists have been investigating the eruption for several days. Ramon Otriz, coordinator of a government scientific team, on Sunday said the emission of sulfur could be the first of four stages of the eruption. \"The second stage could see a column of white smoke, the same color as steam, which will then give way to some explosions that are black in color,\" he stated, adding that the explosions would not put the population at risk. The final stage, according to Ortiz, could be \"the creation of a small island from which a flow of lava could spread.\" However, Otriz said the possible creation of such an island would depend on the amount of lava expelled by the volcano. He added that the volcano was currently expelling gas from an opening that is approximately one meter in diameter confirmed that the eruption would be visible when it reaches a depth of just 60 meters from the surface. So far, villages close to the south-west coast of the El Hierro island, with a surface area of 268 square kilometers and a population of just under 11,000, have been evacuated for precaution. The Canary Islands\' regional government also raised the level of alert over the eruption on Saturday to \"red,\" which means that necessary logistic means will be mobilized for any future evacuations and interventions.