Scientific drilling unravels historical mystery surrounding Santorini volcanic archipelago

A world workforce of scientists co-led by Dr. Steffen Kutterolf from GEOMAR Helmholtz Middle for Ocean Analysis Kiel has discovered proof of a historic submarine eruption of the Kameni volcano on Santorini for the primary time. Of their paper, published at the moment within the journal Nature Geoscience, they describe newly found pumice and ash deposits that help historic data of an underwater eruption in 726 CE.

The Greek island group of Santorini, well-known for its picturesque white homes with blue roofs, is just not solely a preferred vacationer vacation spot but in addition one of the crucial totally explored volcanic archipelagos on the planet. The islands, organized in a round sample, type the rim of a sea-flooded caldera—the basin-shaped melancholy left by previous eruptions.

At its heart is the at present lively Kameni volcano, whose peaks type the islands of Palea Kameni (Outdated Burnt Island) and Nea Kameni (New Burnt Island). The archipelago was fashioned after the devastating Late Bronze Age Minoan eruption some 3,600 years in the past, when the earlier volcano erupted huge quantities of ash and pumice and ultimately collapsed, creating the enduring caldera partitions of Santorini.

Nevertheless, this wasn’t the primary caldera collapse in Santorini’s historical past. “We now know of not less than 5 such occasions throughout the final half million years,” says lead writer Dr. Jonas Preine, who accomplished his doctoral research on the Christiana-Santorini-Kolumbo volcanic field at Universität Hamburg.

“Like different giant volcanic methods, Santorini goes by means of caldera cycles. After a really giant caldera-forming eruption, the brand new cycle is believed to start with small however frequent eruptions because the volcanic system recharges. It then continues to mature, and eruptions turn into bigger however much less frequent earlier than the system is able to produce one other caldera-forming eruption.”

This usually happens over durations of tens of hundreds of years. Santorini is at present in a section of magma accumulation however continues to be a good distance from one other caldera collapse. At this stage, no main explosive eruptions are anticipated.

Nevertheless, the brand new seismic and drilling experiments and the following geochemical analyses at GEOMAR problem this speculation: an eruption within the early summer season of the 12 months 726 has been detected and reconstructed at numerous factors within the drill cores from inside and outdoors the caldera.

Historic writings recount witnessing the ocean boiling “as if heated by an incandescent furnace.” Massive blocks of pumice have been ejected in such amount that they coated the ocean floor of the ocean over an unlimited space and have been carried by the wind to the coasts of Asia Minor and Macedonia.

It has been prompt that the sudden look of floating rocks within the Aegean Sea could have prompted Emperor Leo III of Constantinople, fearing divine displeasure, to impose iconoclasm, a ban on the show of non secular symbols, which brought on extreme socio-economic instability within the Byzantine Empire. Except for these historic accounts, concrete proof for this eruption has been missing till now.

Have been the experiences exaggerated? Or had the historic writers confused Santorini with one other volcano?

The worldwide IODP Expedition 398 “Hellenic Arc Volcanic Area” set out aboard the drilling vessel JOIDES Decision to uncover remnants of this historic eruption. Excessive-resolution seismic reflection information collected beforehand hinted at thick sediment layers of unclear origin.

Via drilling to depths of as much as 300 meters, the workforce managed to assemble proof of the huge underwater eruption in 726 CE: The investigations revealed a layer of grey pumice and ash, as much as 40 meters thick, unequivocally linked to a single eruption.

“This eruption will need to have taken place largely underwater throughout the flooded caldera, as nearly no deposits from the eruption have been discovered on land,” says Dr. Jens Karstens, marine geophysicist on the GEOMAR Helmholtz Middle for Ocean Analysis Kiel and second writer of the research. “That is according to the historic eyewitness experiences.”

Jonas Preine emphasizes that the 726 CE eruption was 30 instances smaller than the well-known Minoan eruption and says, “There isn’t a indication {that a} related eruption will happen within the close to future.”

However, the brand new insights into Santorini’s volcanic habits have important implications for hazard evaluation, because the analysis means that even throughout the early phases of the caldera cycle, bigger explosive eruptions can happen. Moreover, the outcomes spotlight the necessity for larger consideration to submarine eruptions.

Preine says, “If we have been unaware of the deposits of such a big eruption from a volcano as nicely studied as Santorini, we should assume that our world eruption data have a major blind spot for submarine explosive eruptions.”

Recognizing the potential for harmful explosive eruptions within the early levels of caldera formation might be essential in growing extra complete danger mitigation methods.