Can't fault the funding: earthquake research projects granted nearly $3m from Marsden Fund

Listening to the Earth’s “pervasive hum” could give us clues into how the ground will shake when the Alpine Fault next ruptures.

The Kekerengu Fault, one of more than 20 faults that ruptured in the magnitude 7.8 Kaikōura earthquake in November 2016.
The Kekerengu Fault, one of more than 20 faults that ruptured in the magnitude 7.8 Kaikōura earthquake in November 2016.

The Marsden Fund has granted nearly $3 million towards three separate earthquake research projects this year, two focusing on the Alpine Fault.

One is headed by Professor John Townend​ at Victoria University, and has been granted $960,000 to investigate the effects of ground shaking, which could help us to be better prepared.

Townend is part of the Victoria's School of Geography, Environment and Earth Sciences and, together with Dr Caroline Holden of GNS Science, is launching a project to install seismometers along the South Island fault.

Historically, the fault causes a magnitude 8 earthquake around every 300 years. The last one was in 1717.

Of course, these things don’t run like clockwork, “but we’re in the later stages of the typical earthquake cycle”, Townend said.

The research would involve installing seismometers every 10km along the fault, from Milford Sound to Maruia, near Springs Junction.

The project’s novelty was what the team could do with the huge amounts of background noise the sensors recorded – “the Earth’s pervasive hum”.

At first glance, seismic noise appeared random, Townend said, but it contained coherent signals that could be extracted using techniques members of the team developed and used successfully in California and Japan.

By comparing the noise recorded at each point along the fault with noise recorded elsewhere, the team could simulate the ground-shaking produced by a future earthquake.

“It’s possible to accurately synthesize the waves produced by slip anywhere on the fault without having to wait for an earthquake."

The funding would enable the team to deploy the seismometers, some requiring helicopter rides and bush bashing to install.

As well as paying salaries, it would also help fund two PhD scholarships to keep the research going for years to come.

The plan was to put instruments out early next year, leave them out as long as possible, probably another year, check them every two months, and then analyse the seismic noise they picked up.

The Marsden Fund granted a total of $84.7 million to 134 research projects, including another $960,000 to another GNS scientist, Dr Laura Wallace, for research on what makes slow earthquakes episodic, focusing on the Hikurangi fault.

A further $960,000 is going to GNS scientist Russ van Dissen, for research into earthquake rupture directions, a topic which could help determine the extent of the damage in Wellington, at the tip of the Alpine fault, when it ruptures.

Van Dissens’ team will dig into the Alpine and Wairau faults, to document the scratch lines or “slip striations” to determine which way the faults might rupture again.

“The direction of rupture of future quakes on these faults will have a significant influence on the strength of shaking experienced across the South Island and the lower North Island,” Van Dissen said.

The magnitude 7.8 Kaikōura earthquake in November 2016 sent a pulse of energy northwards felt strongly in Wellington, because of its south to north rupture direction.

“If we can show that both faults have ruptured a number of times in a certain direction, then that information could be used to better plan for future earthquakes, and in designing more resilient buildings and infrastructure,” Van Dissen said.

“Large faults are like a heavyweight boxer – you know they are going to pack a wallop.

So if you want to prepare yourself, it’s helpful to know which direction the energy is going to coming from.”

Original article can be found here on Stuff.