Quake risk from drilling tiny

A109 Light Utility Helicopter flight with mayor Gisborne City from the air in November 2023.

Opinion

Some Gisborne-East Coast residents have expressed concerns about risks to the environment after the government-initiated consultation process on future oil and gas exploration in northern parts of the East Coast Basin. These concerns relate to the initiation of earthquakes and tsunami from exploration drilling activities.

GNS Science undertakes earth science research throughout New Zealand, so it can provide independent information to help in the formation of policy and regulation. In doing this, it is required to remain neutral and focus on high-quality, defensible science.

One of the concerns in Gisborne is the risk that an exploration well, particularly an offshore one, might trigger a damaging earthquake. Our observation is that the risk of this happening is extremely small, and probably too small to measure. Indeed, we cannot find any record of such an event in over a century of oil exploration in New Zealand, including the 50-odd wells drilled in the East Coast-Wairarapa region over that period.

The other issue, and one that is more of a risk, is the potential for damage to oil industry infrastructure due to earthquake ground-shaking or a tsunami, resulting in oil leaking into the sea.

Any company undertaking production would certainly need to quantify this risk, and include mitigation strategies, to gain approval from the Environmental Protection Authority.

Getting to the point of extracting oil and gas from the ground takes many years, and during that time companies will need to satisfy an extensive set of regulations.

In Taranaki, for instance, a large amount of earthquake engineering is required for both onshore and offshore facilities. So there is an extensive body of knowledge not just in New Zealand, but internationally, on how to mitigate earthquake risk in this industry.

It is worth noting that similar risks apply to a wide range of on-land activities and locations where petroleum products are stored or transported.

We are not saying that oil exploration is risk-free. But there is a large amount of know-how, accumulated over many decades, on building in measures to manage these risks.

John Callan

GNS Science

The Editor responds