Shaking things up: University of Calgary researchers one step closer to predicting mega earthquakes

Scientists in Calgary are looking at density changes in the earth's crust that impact gravity, so they can predict when a catastrophic event is coming and warn people before it happens.

A mega earthquake is a seismic event with a magnitude of 9.0 or greater, occurring when the edge of one tectonic plate moves beneath the edge of another.

Mega earthquakes are cyclical, occurring every 300 to 500 years.

Scientists believe one is due in the Pacific Northwest within the next 50 years.

Jeong Woo Kim, a geomatics engineering professor at the University of Calgary's Schulich School of Engineering, leads a research team made up of PhD candidates in a project called "Micro Gravity Monitoring of Earthquakes."

Kim says a seismometer is the best method to record an earthquake after it happens because it measures the vibrations of the event.

"It is theoretically almost impossible to detect any precursor because it must have a rupture and the vibration," he said.

"But every single mega earthquake is accompanied with mass redistribution, which can be detected by micro gravimeter."

And it's that tool the team has set up at the Pacific Geoscience Centre located in Sydney on Vancouver Island.

The team has been analyzing data from the sensor for years.

Kim says plate tectonic earthquakes are the most common and devastating natural disasters.

He and his team are focusing their research on density increases surrounding crustal compression and how it impacts gravity.

He says those could be key factors in helping predict the next mega earthquake off Canada's west coast.

"The objective is to catch any precursor, which has never been done," Kim said.

"But this project is possible because we use a superconducting gravimeter, which can detect very small variations of change of mass under ground."

The Cascadia Subduction Zone stretches from Alaska to California and is a tectonically active zone where the younger and heavy Pacific plate subducts beneath the North American plate.

The research project started 19 years ago.

Hojjat Cabirzadeh worked on it for 11 years as its lead author.

"When this plate dives beneath (the) North American, it causes a deformation," he said.

"The deformation happens because this plate is in a locked secured situation but the movement is still going on and the more it moves, the more energy is accumulated on the North American plate.

"This movement is a few centimetres per year but when it comes to a few hundreds of years, the results would be great and that causes an earthquake in the future."

Zahra Ashena, a PhD candidate who's worked on the project since 2018, is using artificial intelligence that's not common in geophysics studies.

"It's something actually new, so I'm trying to figure out what to do with AI for geophysics and it's kind of interesting for me," Ashena said.

"I model the layers, the structure of whatever is inside the earth, (and) I'm using artificial intelligence as an inversion technique, so we have some gravity or magnetic data that we use to model the structure like the density, the geometry of the anomalous bodies under the earth."

Masume Akbari has been on the team for three years and is looking for minute gravity changes to increase chances of predicting a mega earthquake.

"We have this idea that gravity is 9.8 but it's not that," she said.

"It is changing all around the earth and the changes are small, but we need to have them and with those, we can work around with a lot of scientific facts."

Kim says the ability to predict large-scale earthquakes could save thousands of lives.

"Some people think it doesn't matter if you know the earthquake is coming one second earlier," he said.

"But it makes lots of difference because we can stop, for example, an express train and we can give enough time for people to be evacuated so even one second actually matters."