Showcase Tag: Geophysics

Preparing for Climate Change’s Effects with Geophysics

As climate change causes ever increasing fears of flooding, Dr. Peter Lelievre’s work in geophysical imaging becomes ever more important in the province of New Brunswick and beyond.

An assistant professor in Mount Allison University’s department of mathematics and computer science, Dr. Lelievre is an applied geophysicist who images what’s underground. Earlier in his career, that pursuit was tied to mineral exploration or “trying to help people find the materials such as metals that our society uses for basic building materials.” More recently, he’s become interested in imaging and understanding what happens with flood infrastructure.

“With climate change and rising sea levels, we need to understand more about how water moves through these flood barriers,” Lelievre explains. “Geophysical imaging can help us better understand these things, and also to try and find any erosional issues that could cause a breach.”

Lelievre walks on the fields and marshes near Sackville, N.B. — which are the same places his research now takes place. Being at Mount Allison means he’s surrounded by the dike land and he, his wife, and his dog walk on it frequently.

“It’s far more at the forefront of my mind in my daily life,” he says. “It’s been really nice to be able to shift and connect my research to that part of the local community and my daily life.”

Lelievre uses tools that measure electrical and electromagnetic fields and then he uses heavy mathematical methods and computational power to process the data.

“We run the data through these algorithms that we develop and this creates an image of what’s underground,” he says of his use of the Digital Research Alliance of Canada’s high-performance computing tools. “That’s where the heavy computational part fits in. These are tremendously large computational problems.”

For his heavier research, an imaging task could require 600 central processing units (CPUs), consume roughly two terabytes of random access memory (RAM) and take over four-days to finish. He and his research team use the modern Fortran programming language and create their own software to process their electrical and electromagnetic data and generate images of the Earth.

With the help of his students, postdocs and colleagues, he develops data processing methods that could be used in the field, and he collects field data to help test those methods.

“Eventually we’d like to be able to create data processing methods we can use in the field on a laptop, and so you’d just have a small, everyday laptop, where you get a result in effectively real time,” he says, and adds that the history of computing tells us that could well happen in the near future.

Mining Data to Mine Metals, Among Other Things

Geophysics professor has the key to determining how deep down a mineral deposit might be without digging a hole.

Geophysicist Colin Farquharson is a mining executive’s dream come true and maybe even a godsend to a detectorist with deep pockets.

The professor at Memorial University’s Department of Earth Sciences can take the data from geophysical tools that collect information on everything from metallic ore deposits to water sources and determine how deep these prospects are, unlocking great potential for whomever has asked him to do so — or at least information on whether they should pursue a specific site.

“Any scenario where you want to figure out what’s down in the ground without digging a hole — that’s where geophysics comes in,” Farquharson explains.

The equipment used by prospectors is often a helicopter that slings out a loop-shaped transmitter that’s 20 metres in diameter. The transmitter loop has electric current running through it and will offer a response if the helicopter happens to fly over, for example, an ore deposit, even if it’s embedded in rock.

“Metallic ore deposits tend to have a higher electrical conductivity than the rocks they’re sitting in, so they can conduct electricity, which is a bit surprising but true,” he says. “So these are geophysical methods where it’s exactly like the metal detectors people use when they’re trying to find relics and treasure.”

The main application for what Farquharson does is mining, but there are others, too. Often, instead of precious metals, geophysical equipment is used to look for sources of water, particularly in developing countries that might have fresh water aquifers near the coast with ocean water causing problems by creeping in.

Once the equipment determines there is something desirable there, the next thing the prospectors want to know is how hard it’ll be to unearth.

“People want to know how deep those deposits might be to determine whether it’s worthwhile pursuing,” Farquharson says. “That’s where computer modelling comes in. We use the information to calculate synthetic data.”

But making those calculations can be expensive and computationally challenging so Farquharson takes advantage of the high-performance computing power offered by ACENET.

“We can do in hours what would otherwise take weeks and weeks,” says Farquharson, who often gets his graduate students to run the datasets. “Some of the datasets are rich. Even on ACENET some of my students find it’s taking a few days to do these computations.”

He says the support services ACENET provides have been extremely useful to him and his students.

“It’s really valuable to me to have ACENET and the Digital Research Alliance of Canada, which both have big computers that are accessible for free. It doesn’t cost me anything for what I do, so it means I’m not spending thousands of dollars to do that part of my work.”