Fault monitors installed off Gisborne's coast

Keeping an eye on the Hikurangi subduction zone.

Keeping an eye on the Hikurangi subduction zone.

Expedition co-leaders Dr Demian Saffer of Pennsylvania State University and Dr Laura Wallace of GNS Science with one of the observatory wellheads before it was installed in the Hikurangi subduction zone east of Gisborne. Pictures by Tim Fulton
Te Matakite before send off.

Two sub-seafloor observatories have been installed 30 kilometres off the coast of Gisborne to monitor the activity of the Hikurangi subduction zone.

The observatories, one named by Gisborne students, are at the northern end of the subduction zone, where the Pacific plate dives beneath the North Island, by international scientists on board research vessel JOIDES Resolution.

Within five years, scientists will return to both observatory sites to retrieve the data collected.

The observatories are intended to monitor slow-slip events, or silent earthquakes, that commonly occur on the tectonic plate boundary off the East Coast.

Research into slow-slip events pinpointed this fault site as one where these silent earthquakes might be propagating up to the seafloor, so the scientists chose to position the observatory instruments below, within and above the fault.

The expedition was led by Dr Demian Saffer of Pennsylvania State University and Dr Laura Wallace from GNS Science.

Dr Saffer was thrilled with the installation.

“Observatories are notoriously difficult to install, due to the deep-water depths and tools required, but we are thrilled both were deployed successfully over the two-month voyage.

“The observatories will be able to detect tiny changes in the rock and sediment surrounding the subduction fault and provide clues about how and where stress is building or being relieved.”

Dr Saffer said the purpose of the observatories was to test a broad range of questions about slow-slip events and their relationship to large, destructive earthquakes and tsunamis.

Both observatories will listen to the ‘‘creaks and groans’’ of the subduction zone and are the primary method scientists have to continuously collect this data over many years, directly from the source of the slow-slip events.

One of the observatories is named Te Matakite which means ‘‘to see into the future’’. Living up to its name, it will sense and measure changes in the fault zone that human eyes cannot see or record in any other way. It was named by Gisborne Boys’ High School students.

This information will provide new insights into why the subduction zone is behaving as it is and improve understanding of hazards posed to the East Coast by earthquakes and tsunami.

Te Matakite was installed 450 metres below the seafloor into an active fault that splits off from the main Hikurangi megathrust fault.

Dr Wallace said she hoped the observatories would pave the way to additional long-term measuring equipment installed in the Hikurangi subduction zone, which could also contribute to improved tsunami warning in the future.

“The puzzle we are putting together on the JOIDES Resolution will help subduction zone scientists around the world to better understand earthquakes and the slow-slip phenomenon.

“As for people living near subduction zones, it will be used to improve hazard and risk models of earthquakes and tsunamis.

“Better understanding of what could happen will lead to improved preparedness and fewer lives lost.”

New Zealand participates in IODP through a consortium of research organisations and universities in Australia and New Zealand.

  • The scientific drilling ship JOIDES Resolution is funded by the US National Science Foundation.

Two sub-seafloor observatories have been installed 30 kilometres off the coast of Gisborne to monitor the activity of the Hikurangi subduction zone.

The observatories, one named by Gisborne students, are at the northern end of the subduction zone, where the Pacific plate dives beneath the North Island, by international scientists on board research vessel JOIDES Resolution.

Within five years, scientists will return to both observatory sites to retrieve the data collected.

The observatories are intended to monitor slow-slip events, or silent earthquakes, that commonly occur on the tectonic plate boundary off the East Coast.

Research into slow-slip events pinpointed this fault site as one where these silent earthquakes might be propagating up to the seafloor, so the scientists chose to position the observatory instruments below, within and above the fault.

The expedition was led by Dr Demian Saffer of Pennsylvania State University and Dr Laura Wallace from GNS Science.

Dr Saffer was thrilled with the installation.

“Observatories are notoriously difficult to install, due to the deep-water depths and tools required, but we are thrilled both were deployed successfully over the two-month voyage.

“The observatories will be able to detect tiny changes in the rock and sediment surrounding the subduction fault and provide clues about how and where stress is building or being relieved.”

Dr Saffer said the purpose of the observatories was to test a broad range of questions about slow-slip events and their relationship to large, destructive earthquakes and tsunamis.

Both observatories will listen to the ‘‘creaks and groans’’ of the subduction zone and are the primary method scientists have to continuously collect this data over many years, directly from the source of the slow-slip events.

One of the observatories is named Te Matakite which means ‘‘to see into the future’’. Living up to its name, it will sense and measure changes in the fault zone that human eyes cannot see or record in any other way. It was named by Gisborne Boys’ High School students.

This information will provide new insights into why the subduction zone is behaving as it is and improve understanding of hazards posed to the East Coast by earthquakes and tsunami.

Te Matakite was installed 450 metres below the seafloor into an active fault that splits off from the main Hikurangi megathrust fault.

Dr Wallace said she hoped the observatories would pave the way to additional long-term measuring equipment installed in the Hikurangi subduction zone, which could also contribute to improved tsunami warning in the future.

“The puzzle we are putting together on the JOIDES Resolution will help subduction zone scientists around the world to better understand earthquakes and the slow-slip phenomenon.

“As for people living near subduction zones, it will be used to improve hazard and risk models of earthquakes and tsunamis.

“Better understanding of what could happen will lead to improved preparedness and fewer lives lost.”

New Zealand participates in IODP through a consortium of research organisations and universities in Australia and New Zealand.

  • The scientific drilling ship JOIDES Resolution is funded by the US National Science Foundation.

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