Seafloor study in Chilean Patagonia reveals volcanic impact
An international team of scientists is reconstructing the impact of the 2008 Chaitén volcanic eruption on the marine environment following an expedition onboard Schmidt Ocean Institute’s RV Falkor (too). During the 21-day research cruise in September, scientists found eruption debris more than 25km away from the volcano, transported into the sea via the local river system and then dispersed by ocean currents. Their findings provide new insights into the fate of volcanic debris in marine environments and the strength of the current systems in Chile’s northern Patagonian Sea. This, along with new seafloor maps, will help scientists to understand volcanic hazards in southern Chile and how they have changed over time.
After 9,000 years of dormancy, the Chaitén volcano erupted without warning on 2 May 2008. Ash spewed 30km into the air and blanketed the landscape. Heavy rain in the following days triggered devastating volcanic mudflows known as lahars that cascaded down mountainsides and into the northern Patagonian Sea. The town of Chaitén evacuated as the powerful mudflows inundated and transformed the landscape, flooding the city with mud and destroying the buildings on the southern side.
Glacially sculpted seafloor
Using a vibrating coring device mounted on the Schmidt Ocean Institute’s ROV SuBastian, the scientists gathered seafloor sediment cores from the northern Patagonia Sea offshore to the Peru-Chile Trench. Layers of mud within the cores provide a record of the region’s geologic and oceanic activity. Volcanic ash and debris indicate the occurrence of past eruptions in the area. These event layers are better preserved in ocean sediments than on land, shedding light on past events and providing the data needed to predict future volcanic hazards and assess how eruptions impact the marine environment.
The scientists mapped an area of seafloor approximately 2,700km2 in the fjords of the northern Patagonian Sea and collected subseafloor data, imaging metres below the seafloor, to assess the build-up and movement of sediment. The mapping revealed a stunning, glacially sculpted seafloor. Scientists have long known that the area was carved by glacial erosion but were surprised by the magnitude of observable ice scouring.
“Approximately half of the Earth’s volcanoes are islands or located near coasts, like Chaitén,” said Schmidt Ocean Institute’s executive director Dr Jyotika Virmani. “It is amazing that as recently as 2008, this volcanic eruption wasn’t predicted. Understanding volcanic activity and its footprint on the offshore ecosystem provides data to more readily predict the frequency and severity of events, which is essential to saving lives and cultures.”
For the full version of this story, please visit the Schmidt Ocean Institute website.
