New research offers theory for origin of subduction zone

In 2018, a group of scientists boarded the research vessel Marcus Langseth to study the Puysegur margin. This voyage, part of the South Island Subduction Initiation Experiment, set out to find answers to how subduction zones form.

Since subduction zones are by nature destructive, they are difficult to study. The Puysegur margin, a fairly young subduction zone, has not yet matured enough to have lost its history, making it an ideal location to study the nature of subduction zones. However, the region is located in the “Roaring Forties,” between latitudes 40 and 50 degrees south, where currents as well as winds make exploration challenging.

Despite the brutal conditions, researchers deployed seismometers along the ocean floor and gathered seismic survey data of the subsurface using reflected sound waves to “see” underground structures. Using the data collected, the researchers developed a working theory of the subduction zone’s history. The lead researcher, Brandon Shuck, a doctoral candidate at The University of Texas at Austin, presented the findings at the Seismological Society of America’s virtual meeting on 22 April 2021, coinciding with the study’s publication in the journal Tectonics. According to Shuck, a key finding to understanding the development of subduction zones was the difference in the buoyancy of the two plates in the region and the weakening of their boundary by earlier strike-slip faulting.

If weather allows, the team plans to return to the region in November 2021 to continue their research.

For further exploration:

A hidden continent birthed a new subduction zone near New Zealand

Strike-Slip Enables Subduction Initiation Beneath a Failed Rift: New Seismic Constraints From Puysegur Margin, New Zealand