What Happens When Lava Hits the Ocean? La Palma Volcano's Flow Heading for Atlantic

Residents of the coastal villages on a Spanish Canary island are preparing for the dangerous effects of lava from the Cumbre Vieja volcano hitting the Atlantic Ocean.

The volcano on the island La Palma began to eject lava again on Monday after a quieter period of activity.

With the lava traveling at around half a mile per hour, AS reported that the authorities had originally believed it could have reached the ocean on Monday evening. The destructive lava flow slowed when it hit flatter areas of the island, delaying the interaction.

One of the first effects of the 1,100ºC lava hitting the ocean will be the water beginning to boil and create steam. As the lava boils away the seawater, more of its surface is exposed to the water, which transfers heat more quickly, the U.S Geological Survey (USGS) Volcano Watch says.

Steam is then produced at a more rapid rate. The clouds created can be lethal as they often contain small glass fragments.

When part of an active lava flow stacks up and forms a bench, this shelf can collapse into the ocean. When the large surface of lava hits deeper water, Volcano Watch says the result can be flash steam that can lead to explosions of varying magnitudes. The explosions can cause fragments of molten rock and volcanic glass, created when the lava rapidly cools, to be launched into the air.

Fragments tend to be launched in all directions at random, and large pieces have been blasted hundreds of meters inland in the past.

In addition to the steam created when lava meets water, the result can also be lava haze, or just "laze," which is highly acidic and can contain chlorine.

"This mixture has the stinging and corrosive properties of dilute battery acid, and should be avoided," says the USGS. "Because laze can be blown downwind, its corrosive effects can extend far beyond the actual ocean entry area."

Though most dangerous at the point where the lava meets the water, when carried inland, laze can produce acid rain that could result in health risks like skin and eye irritation and breathing problems.

The Copernicus Emergency Monitoring System (CEMS) is currently monitoring the situation on La Palma as it develops and has been tracking the flow of lava since the eruptions began on September 19.

As of Monday, the CEMS estimated that the lava flow had destroyed 513 homes and almost 12 miles of roadway.

In addition to the 5,000 La Palma residents evacuated during the early stages of the volcanic eruption and 2,000 more evacuated as the lava progressed through the island, Reuters reported that about 300 residents in the coastal areas of San Borondon, Marina Alta and Baja, and La Condesa have been instructed to stay in their homes in anticipation of the potentially harmful effects that arise when lava meets seawater.