Copernicus, the European Union’s Earth observation program, said Thursday its satellite images showed a D-shaped tongue of molten rock accumulating on the island’s west coast measuring 338 hectares (835 acres) at the end of Wednesday.
The typical trade winds of the Spanish Canary Islands helped dispel the plumes of water vapor and toxic gases that occur when lava with a temperature of over 1,000 degrees Celsius (1,800 F) meets the ocean, where the water is 22 degrees Celsius (71.6 F).
But authorities were on high alert as Spain’s weather forecaster, AEMET, said the wind direction could change later Thursday and bring the toxic plumes ashore and further inland.
Hydrochloric acid and tiny particles of volcanic glass released into the air can cause irritation to the skin, eyes and respiratory tract.
The direction the lava flow might take was also of concern. The molten fluid emanating from the volcano that first erupted on September 19 still descended like a river, then tumbled off a cliff into the Atlantic. But rugged terrain could cause lava to overflow its current path, spread to other areas, and destroy more homes and farmland.
At least 855 buildings and 30 kilometers (18.6 miles) of roads, as well as other key infrastructure, have been destroyed so far. Banana plantations which are the source of income for many islanders have also been destroyed or damaged by volcanic ash.
More than 6,000 residents have been evacuated so far, and hundreds more have been urged to stay in their homes to avoid possible inhalation of toxic gases. No casualties or injuries have been reported among residents of La Palma since the eruption began.