High-tech $120 million mission to drill deep-sea observatories below NZ's largest earthquake and tsunami threat

An ambitious mission to drill two deep-sea observatories 500 metres below the sea floor along New Zealand's largest earthquake and tsunami threat, the Hikurangi subduction zone, will begin next week.

A team of international scientists will board the scientific drilling ship, JOIDES Resolution, and travel east off the coast of Gisborne to New Zealand's largest fault line.

There along the Hikurangi subduction zone they will install two bore-hole observatories containing high-tech measuring and monitoring equipment designed to pave the way for early earthquake and tsunami warning systems.

The observatories are to remain under the sea floor for five to ten years, and deliver readings on a lesser known movement of tectonic plates beside earthquakes - slow-slip events.

"Slow-slip events or slow-slip earthquakes are similar to earthquakes, because they involve more rapid than normal movement along a fault," expedition co-leader, Dr Laura Wallace of GNS Science explains.

"However, during a slow-slip event it takes weeks to months for this fault movement to occur.

"This is very different from an earthquake, where fault movement occurs over a matter of seconds releasing energy suddenly."

The sub-sea floor observatories will be installed east of Gisborne and remain in place for up to 10 years recording valuable information about the conditions inside the Hikurangi Subduction Zone. Source: Supplied

The expedition jointly led by scientists from New Zealand's GNS Science and Pennsylvania State University hopes to reveal new insights into the causal relationship between slow-slip events and large earthquakes.

The Hikurangi subduction zone runs from Marlborough past New Zealand east coast in the Pacific Ocean, and is thought by scientists to be capable of causing magnitude 9 earthquakes leading to potentially devastating tsunamis along the New Zealand coast line.

"Slow-slip events are enigmatic because we don't yet understand the physical processes that cause faults to behave in such a way, and we don’t know very much about their relationship to large subduction zone earthquakes," expedition co-leader Dr Demian Saffer, of Pennsylvania State University, says.

Last year's Kaikōura earthquake triggered a large slow-slip event off the east coast covering an area of more than 15,000 square km.

The slow-slip event started in the region of the planned drilling, and the results from this research is expected to shed light on why this occurred.

The drilling project is funded by the International Ocean Discovery Program and the US National Science Foundation, and is the first of its kind off the New Zealand coast.