The formation of the Andes Mountains from the convergence of the Nazca plate and the South American plate is a well-known example of subduction zones. These zones, where one tectonic plate dives underneath another, are responsible for some of the world's most devastating earthquakes and tsunamis. A recent study in Geology suggests that subduction can spread like a contagion, jumping from one oceanic plate to another, a phenomenon that was previously challenging to prove.

According to University of Lisbon geologist João Duarte, who was not part of the research, this finding is not mere speculation but is backed by evidence from the geological record. The study sheds light on how subduction, which involves dragging crust deep into the earth, can be initiated and spread.

The research presents an ancient example of potential subduction 'infection' that led to the creation of East Asia's 'Ring of Fire,' a massive subduction system responsible for earthquakes and volcanoes from Alaska to the southern Indian Ocean. The study suggests that nearly 300 million years ago, China was a collection of islands separated by the Tethys and Asian oceans. Subduction zones from these oceans eventually merged the landmasses into a single continent, giving rise to mountains from Turkey to China. By 260 million years ago, this subduction process had spread and started pulling down the neighboring Pacific plate.

The 'Dupal anomaly,' a geochemical fingerprint from the ancient Tethys Ocean and the Indian Ocean, serves as evidence of this subduction spread. This signature was unexpectedly found in volcanic rocks from the western Pacific, indicating that material from the Tethys had moved eastward across a plate boundary, triggering the descent of the neighboring plate. The mechanism of this spread remains unknown, but researchers suspect that transform faults, where plates slide past each other, could play a role in destabilizing dense oceanic crust.

Looking ahead, there is speculation about whether the relatively quiet plate margins of the Atlantic Ocean could be the next target for subduction spread. The 1755 Lisbon earthquake suggests early subduction invasion in the region. Duarte believes that parts of Iberia and the Caribbean are currently in the initial stages of this process, hinting at a possible formation of a new Atlantic 'Ring of Fire' in the next 100 million years, similar to what occurred in the Pacific.