Probing the Australian-Pacific Plate Boundary: Macquarie Ridge in 3-D

Voyage Number

IN2020_V06

Voyage Dates

08 Oct, 2020 to 03 Nov, 2020

Voyage Location

Hobart to Hobart

Chief Scientist

Prof Mike Coffin

Institution

Institute for Marine and Antarctic Studies (IMAS)

View the full voyage

Voyage summary

Research voyage to the Southern Ocean to study the geological structure and evolution of Macquarie Ridge including Macquarie Island. Macquarie Island lies in the Southern Ocean halfway between Antarctica and New Zealand. It is located at approximately 55˚S and sits on the highly active tectonic plate boundary between the Australian and Pacific plates. The island, which is part of Tasmania, is listed as a World Heritage Place because of its unique geological exposures of both crustal and mantle rocks.

This voyage has two main aims:

1. image Earth structure by utilising state-of-the-art seismological techniques in conjunction with a carefully designed configuration of ocean bottom seismometers (OBS) pointing towards the Earth’s centre like a giant antenna
2. better understand the physics of the planet’s largest underwater earthquakes not associated with active subduction.

The voyage will produce the first high-resolution maps of much of the seafloor surrounding Macquarie Island, including seafloor lying within the Macquarie Island Nature Reserve and Macquarie Island Marine Park. During the voyage, 29 OBS will be deployed on the seafloor around Macquarie Island in water depths between 650m and 5500m. Researchers will use these instruments to investigate the region’s geological structure as well as its seismic activity.

The OBS (and their data) will be recovered in late 2021 or early 2022. This research project is part of an international project involving the University of Cambridge and Caltech, and will help enable better monitoring of future earthquakes and tsunamis that could affect Australia and New Zealand.

This voyage includes 20 science participants from three institutions: CSIRO, Institute for Marine and Antarctic Studies (IMAS) and the Australian National University (ANU). This is the minimum science team required to achieve voyage objectives.

COVID-19 Protocols

To safeguard the health and well-being of participants, strict COVID-19 protocols will apply to all activities on this voyage, including testing of all participants for COVID-19 prior to departure.

Voyage outcomes

Passive seismological and marine geophysical 3D imaging of the central Macquarie Ridge Complex (MRC) and Macquarie Island will be of immediate benefit for understanding the tectonic evolution of the Australian-Pacific plate boundary and the mechanisms responsible for earthquake generation in the region. Passive seismology studies will advance understanding of the initiation of tectonic plate subduction, a first order problem in global geoscience, enhance monitoring of this earthquake belt, and provide more accurate estimates of tsunami potential.

Therefore, results will be relevant not only to the seismological research community, but also to national earthquake monitoring programs, such as those operated by Geoscience Australia and New Zealand’s Earthquake Commission and GNS Science. Marine geophysical imaging will provide the first data to enable baseline benthic habitat
mapping around the World-Heritage Listed Macquarie Island, including the Commonwealth Macquarie Island Marine Park and Tasmanian Macquarie Island Nature Reserve – Marine area.

These data will thus contribute to Commonwealth and State of Tasmania management of the marine realm surrounding UNESCO World Heritage-listed Macquarie Island.