The waters surrounding the Campi Flegrei supervolcano in Italy have turned red, signaling increased activity beneath the surface.
The Avernus crater lake near Naples was the first to change color before the phenomenon spread to the waters in the Bay of Pozzuoli. The vivid red hue of the water is caused by a bloom of a type of harmful phytoplankton that thrives in warm temperatures. This toxic algae is highly detrimental to fish and other wildlife in the area. This seasonal phenomenon is typical for the region; however, according to Volcano Discovery, this year’s bloom is particularly intense.
Vivid red waters near Campi Flegrei volcano. (Photo: Enzo Buon)
The rapid algal bloom may be related to the activity of Campi Flegrei, a supervolcano located approximately 14.5 km from Naples. Campi Flegrei is one of the most densely populated active volcanoes, featuring 24 craters and a large caldera. About 2.2 million people live within a 4.8 km radius of the volcano.
The connection between algal blooms and volcanic activity has not been extensively documented. However, some scientists suggest that extreme heat from volcanic activity may stimulate algal growth. The temperatures from the volcano could cause nutrients from the deep sea to rise, promoting the rapid expansion of algae and resulting in the brilliant red color.
Algal blooms can be a concerning sign, as the volcano has triggered a series of earthquakes in the area over the past 30 days, including two quakes measuring 3.5 and 3.6. The largest earthquake recorded in the area in recent decades occurred in 1984, with a magnitude of 4.2.
Campi Flegrei has shown signs of activity over the past 60 years. Experts believe that an eruption is not imminent, but the increased levels of activity may indicate that the volcano is entering a pre-eruption phase. Scientists warn that an eruption of Campi Flegrei could generate tsunami waves nearly 30 meters high, severely impacting coastal areas such as Pozzuoli and Sorrento.
The last eruption of Campi Flegrei occurred in 1538 after a century of pressure buildup. This eruption lasted more than a week but was relatively small compared to the eruption that took place 40,000 years ago.
