Sea water suddenly turns red around the super volcano

The waters around the Campi Flegei supervolcano in Italy turn red, signaling increased activity below the water's surface.

The crater lake Avernus near Naples first turned red before spreading out into the waters at Pozzuoli Bay. The bright red color of the water is the result of a microalgae that thrives in warm temperatures. This harmful algae is very toxic to fish and other wildlife in the area. This is a seasonal phenomenon in the region. However, according to Volcano Discovery, this year, the algae outbreak has been particularly strong.

The fiery red waters near the Campi Flegei volcano.

The rapid algae bloom may be related to the activity of Campi Flegei, a supervolcano located about 14.5km from Naples. Campi Flegei is one of the most densely populated active volcanoes. The mountain has 24 mouths and a large depression. About 2.2 million people live within 4.8km of the volcano.

The link between algal blooms and volcanic activity has not been widely documented. However, some scientists think that the extreme heat from volcanic activity can stimulate algae growth. The heat from the volcano can cause nutrients in the deep sea to rise and help algae grow, causing them to expand rapidly and create a vibrant red color.

The algae bloom could be a worrying sign because the volcano has triggered a series of earthquakes in the area over the past 30 days, including two magnitude 3.5 and 3.6 quakes. The largest earthquake to hit the area in recent decades was 4.2 magnitude in 1984.

The Campi Flegei volcano has shown many signs of activity over the past 60 years. Experts say the eruption won't happen immediately, but increased activity could signal the volcano is entering a pre-eruption stage. Scientists say the eruption of Campi Flegei volcano can cause tsunamis nearly 30 meters high, severely affecting coastal areas such as Pozzuoli and Sorrento.

Campi Flegei last erupted in 1538 after a century of pressure build-up. The eruption lasted more than a week but was still quite small compared to the one 40,000 years ago.