Physical Sciences

Fault lines: ��οresearch could protect cities in active earthquake zones

noreen.rasbach — Tue, 23 Jul 2019 16:53:49 +0000

Fault lines: ��οresearch could protect cities in active earthquake zones

noreen.rasbach Tue, 07/23/2019 - 12:53

Cutline

U of T's Jeremy Rimando sets up Differential Global Positioning System (DGPS) survey equipment to measure the amount of displacement on the Las Chacras Fault in San Juan, Argentina (photo by Cesar Distante)

Blake Eligh

Topic

Breaking Research

Earth Sciences

Earthquakes

Global

Physical Sciences

Research & Innovation

��οMississauga

A study from the University of Toronto Mississauga reveals new clues about an earthquake that rocked Argentina’s San Juan province in the 1950s. The results add important data about one of the Earth’s most active thrust zones and could help to protect cities in the region from earthquake damage in the future.

Jeremy Rimando, the lead author of the study and a PhD candidate in the lab of study co-author Lindsay Schoenbohm, an associate professor in the department of chemical and physical sciences. Their study, published in the journal Tectonics, focuses on the La Rinconada Fault in the western central area of Argentina.

“This region is seismically active and is bound by many thrust faults where one block of land moves over top of another,” says Rimando, who has conducted field research at several sites in the area. “It’s an area that experiences frequent earthquakes.”

The 30-kilometre-long La Rinconada Fault line marks a tectonic transition zone where the thin-skinned crust of the Eastern Precordillera meets the thick-skinned crust of Sierras Pampeanas in the Andes mountain range.The area is arid and rocky, with steep gravel-strewn hills and terraces that reveal the displacement of the Earth’s surface as the land shifts and slips along the fault line.

San Juan, with a population of 500,000, lies 15 kilometres to the north in an area bounded by several faults, including La Rinconada. A 1944 earthquake devastated the city and killed 10,000 people. Eight years later, San Juan experienced another severe earthquake with a recorded magnitude of 6.8. Rimando’s data points to the La Rinconada Fault as a potential generator of the second quake.

To determine if La Rinconada might be connected to the 1952 quake, Rimando calculated the slip rate – how fast two sides of the fault are moving relative to one another – which can provide clues about how often an earthquake might occur.

“We looked at features that were displaced by the fault line,” he says. “A low slip rate is usually associated with a long recurrence interval.”

Long recurrence intervals can mean that earthquakes may not happen often, but when they do, they can be big because of the strain that has built up over time. “If the slip rate is moving slowly, it can eventually build up a large amount of strain, resulting in big earthquakes that take place on a less frequent basis,” he says.

“Our data shows that La Rinconada is moving slowly at 0.4 mm per year,” Rimando says. He notes that the La Rinconada slip rate is associated with earthquakes ranging in magnitude from 6.6 to 7.2. “This is within the range of the 1952 earthquake.”

“Further investigation is required to determine the timing and recurrence interval on this fault, but knowing the very specific likely magnitude is helpful for planners,” says Schoenbohm. “Buildings shake at different frequencies depending on the earthquake, so the most likely magnitude is more important to know than the maximum magnitude. Narrowing that range as much as possible is really useful.

He adds that researchers "can’t definitively say that this was the fault, but we have added to possible proof that it could be because of the similarity in magnitude of the 1952 earthquake and the possible earthquake magnitudes that this fault caused. This information could impact building locations, zoning requirements and engineering infrastructure.”

Funding for the study was provided through the Natural Sciences and Engineering Research Council of Canada Discovery Grant program.

Why was there open water instead of ice north of Greenland this year? ��οexpert has an answer

noreen.rasbach — Wed, 12 Dec 2018 20:32:18 +0000

Why was there open water instead of ice north of Greenland this year? ��οexpert has an answer noreen.rasbach Wed, 12/12/2018 - 15:32

Cutline

A look at sea ice concentration on Feb. 25, which shows a polynya north of Greenland (image courtesy of Kent Moore)

Topic

Research & Innovation

��οMississauga

In the depths of the long night that cloaks the Arctic in frigid darkness for three months each winter, a surprising patch of open water appeared, just to the north of Greenland.

It was a polynya – an area of unfrozen water surrounded by the polar ice pack. Though not especially rare in some parts of the Arctic, the north Greenland polynya of February of this year was an unexpected 50,000 square kilometres of open water in the Wandel Sea, an area the size of the province of Nova Scotia.

The Wandel is part of a region known as the last ice area. It abuts northern Greenland and Canada’s Arctic Archipelago, and sea ice there is expected to persist longer than anywhere else. As recently as the 1980s, its ice cover was thicker than an elephant is tall. Today, it’s about half that.

Was this unusual polynya another harbinger of climate change?

That was the initial hypothesis of a team led by the University of Toronto's Kent Moore and Axel Schweiger of the University of Washington’s Polar Science Center. Polynyas had not previously been observed in the region, and temperatures in north Greenland had been startlingly warm, as much as 30 degrees Celsius above average.

But as Moore, a professor in the department of chemical and physical sciences at ��οMississauga, dug deeper with his colleagues from the Polar Science Center, an alternative explanation emerged.

In their paper, What caused the remarkable February 2018 Greenland Polynya?, Moore, Schweiger, Jinlun Zhang and Mike Steele identify the polynya’s cause to be strong surface winds catalyzed by a dramatic warming in Earth’s upper atmosphere known as a Sudden Stratospheric Warming.

“During these events, temperatures in the stratosphere – about 30 kilometres above ground level — can warm by 10 or 15 degrees Celsius in just a few days,” Moore says.

“This causes a change in air circulation that includes a reversal in the winds in the stratosphere. These high altitude winds blow against the west-to-east direction of the jet stream, descending toward the Earth’s surface. In February 2018, this caused winds from Siberia to blow cold air into northern Europe, creating a weather system that became known as the Beast from the East. It brought temperatures of -20°C to northern Europe, and the same weather pattern moved warmer air northwards up the east coast of Greenland.”

Strong southerly winds forced mild air to Greenland and beyond, but it wasn’t their warmth that caused the polynya.

“Most Arctic warmings last a day or two,” says Moore (pictured left). “This lasted a week, and these were the warmest temperatures and strongest winds observed in north Greenland since observations began in the 1960s. Winds were close to hurricane force and temperatures were above freezing. Once we got that piece of the puzzle, we realized it could be wind rather than warmth that caused the polynya.”

While the size of the polynya was unprecedented over the period that researchers have good data, it appears not to be tied to the thinning of the ice pack that has occurred over the same period. Simulations with the University of Washington’s Pan-Arctic Ocean Modeling and Assimilation System (PIOMAS) indicate that similar conditions would have created a polynya, even without the recent thinning of the ice north of Greenland.

Using the system, the team crunched 2018 weather conditions and ice concentration data to numerically simulate the polynya. Then, using historical data, they simulated 2018 weather conditions on the ice packs of the past.

Their findings: Similar wind speeds would have caused the polynya to occur even in years with thicker ice, while weaker winds would not have resulted in the 2018 north Greenland polynya, despite thinner ice conditions.

“We used to ask the question hypothetically: What would have happened if the ice had been as thick as in 1979,” says Schweiger.

“Now, we simulate it. The answer was that the thinning of the ice didn’t matter much, but strong winds were responsible.”

A longtime sea ice researcher, Schweiger was surprised. He thought thinning ice would be the decisive factor.

“But when we looked closer, it wasn’t. Letting your intuition guide your hypothesis, then letting yourself be convinced otherwise … that’s science!”

Tracing the steps of nearly 10,000 ��οPhDs after graduation

geoff.vendeville — Thu, 01 Feb 2018 05:00:00 +0000

Tracing the steps of nearly 10,000 ��οPhDs after graduation

geoff.vendeville Thu, 02/01/2018 - 00:00

Cutline

PhD students at a convocation ceremony in June 2014 (photo by Johnny Guatto)

Geoffrey Vendeville

Topic

City & Culture

Faculty of Applied Science & Engineering

Rotman School of Management

School of Graduate Studies

Social Sciences

Subheadline

“What we see in the results is the wide variety of job options”

Where do I go from here? It's a question all students ask themselves approaching graduation, and one that is particularly important for students who have devoted five or six years to a PhD.

The answer, it turns out, is anywhere.

In a first-ever survey of PhD graduates from the University of Toronto, the School of Graduate Studies found that alumni who graduated between 2000 and 2015 are working in 97 different countries, with careers ranging from neurosurgeon to user-experience researcher.

About 60 per cent of graduates across all disciplines found work in academia, and roughly a third hold tenure-stream positions. However, the data suggest PhD graduates are increasingly ending up outside the academy. Comparing the cohorts of 2015 to 2000, nearly twice the proportion of PhDs were employed in the private sector (23 per cent as opposed to 13 per cent).

“Partly what we see in the results is the wide variety of job options that PhD students' futures might hold,” says SGS Dean Joshua Barker. “It's really the beginning of a conversation that I think will be very helpful for students as they think about the pathways from their studies into their careers.”

Take a closer look at the data on the SGS website

Employment sectors of all PhDs in the survey by division between 2000 and 2015 (courtesy of the School of Graduate Studies)

The project was initiated by Professor Reinhart Reithmeier, with support from former Dean Locke Rowe. Researchers compiled the data using internet searches of open-access data sources, such as official university and company websites, to determine a PhD’s current employment. They found the professional outcomes of nearly 10,000 former students, or 88 per cent of graduates, over the 15 years covered by the study. With the help of U of T’s Institutional Data Hub, SGS then created an interactive dashboard that allows users to customize their exploration of the data.

Read about the survey in the Globe and Mail

The list of current private-sector employers reads like a who's who of top companies: Google, Intel, Janssen, RBC and Scotiabank figure in the top five. PhD graduates in the post-secondary sector can be found everywhere from Canadian universities to the National University of Singapore. In the public sector, the top employers included the University Health Network, the Hospital for Sick Children and the Centre for Addiction and Mental Health.

Barker, whose own PhD focused on Indonesia during the dictatorship of the 1990s, says ��οgraduates with advanced degrees are well positioned to find jobs in new and interesting fields. “Toronto is emerging as one of the hubs of the knowledge economy, and the specialized training PhDs acquire can play a big part in elevating and expanding innovation locally and globally,” he says.

The data show how ��οcontributes to a “brain gain” in Canada, with nearly half (46 per cent) of permanent residents and international students finding employment here.

The study is not the only good news ��οhas received about the future prospects of its graduates. Over the past several years, the university has consistently led other Canadian institutions in Times Higher Education's global university employability rankings.

Like any study, the SGS survey has its limitations, Barker says. “This study tells us where our recent cohorts of our PhDs have landed, but further research will be needed to understand the pathway that led them there, or how they feel about that pathway.”

��οNews went beyond the numbers by speaking to four PhD graduates and one current student, Hadiya Roderique, about their time here, why they pursued a PhD and how it has prepared them for the future.

Inmar Givoni

Machine learning (2005-2011)

The similarities between the human brain and artificial intelligence are often overstated, Givoni says. But in her case, an early fascination with neuroscience preceded her interest in machine learning.

In high school, she became interested in one of the body's great mysteries: brain functioning. She grew up aspiring to become a neuroscientist, and spent a summer in a lab studying the rat's visual cortex.

She changed her mind after taking a course in machine learning at Hebrew University and switched her focus to artificial intelligence. “I thought, 'OK, I still want to do research, but instead of trying to understand the brain, maybe I can focus on trying to create machines and build algorithms that mimic what the brain does.'”

That goal led her to U of T, a world leader in the field. She was paired with her adviser Professor Brendan Frey, the founder and CEO of startup Deep Genomics, which uses machine learning to develop genetic medicines.

She graduated in 2011 and now applies her research to her work as an autonomy engineering manager at Uber in Toronto. Over and above technical skills, she says she learned to be her own boss.

“You're not doing [the work] because someone is telling you to do it,” she says. “You really have to have the motivation within yourself.”

Helen Marshall

Medieval and Renaissance studies (2008-2013)

Marshall says she wouldn't be the writer she is today if she hadn't pored over medieval manuscripts in university.

She's the author of two short story collections and two poetry collections, and a senior lecturer of creative writing and publishing at Anglia Ruskin University in Cambridge, England,

Her first book of short stories, Hair Side, Flesh Side, takes its title from the animal skins used for parchment. The collection includes Blessed, the story of a seven-year-old girl, Chloe, whose divorced parents give her the bodies of saints in an eerie game of one-upmanship. It starts when Chloe receives the body of St. Lucia of Syracuse as a birthday present from her dad. “It was rough like a cat's tongue in some places and smooth as fine-grained wood in others where the bone peeked through,” Marshall writes. Not to be outdone, Chloe's mom later gives her the body of Joan of Arc.

Marshall told ��οNews she was inspired by a chapter she was writing on medieval saints' lives and how their bodies “had become this odd sort of tourist industry.”

“There was something about taking holy bodies and doing something really mundane and commercial around them,” she says. “It seemed funny to me – an odd paradox of the Middle Ages to play with.”

At U of T, she was part of a writers' group with students in medieval studies and literature – including Kari Maaren, who published her first novel last year.

When she started her PhD, Marshall thought getting her doctorate would mean becoming an expert in one field. “Since then what's surprised me the most is to realize that actually I learned a set of skills that means I can become the expert of any field I want to – because it's about learning the processes of research and critical thinking.”

Emma Planinc

Political science (2011-2017)

There was never any doubt in Planinc's mind: She wanted to be a professor. After studying literature and philosophy at ��οas an undergrad and then taking a master's in political science at McGill University, she returned to Toronto for a PhD in political science.

“Devoting six years of my life to the PhD always felt like a cost I was willing to bear because I thought I couldn't be doing anything else,” she says.

“There is a big transformative moment when you're doing your PhD,” she added, which begins with writing your thesis proposal. The degree gave her the time and freedom to think deeply about the subjects that interest her, including 18th-century French philosophy and natural science. Her dissertation is the basis of her in-progress first book, Regenerating Political Animals, which situates the “Declaration of The Rights of Man and of the Citizen” from the French Revolution within the context of contemporary science, theology and philosophy.

In a way, she's come full circle to her interests in literature and philosophy, having recently accepted a tenure-track position as an assistant professor at the University of Notre Dame in the liberal studies program. In addition to political theory, she will be teaching canonical books like The Odyssey. She starts her new job this fall.

Michael Selvanayagam

Electrical and computer engineering (2010-2014)

Selvanayagam spent part of his PhD working on an idea that sounds straight from science fiction: an invisibility cloak.

He and his supervisor, electromagnetics Professor George Eleftheriades (above, right) in the Faculty of Applied Science & Engineering, developed a device that can hide a metal cylinder from radar detection, or make the cylinder appear smaller, bigger or plastic.

Hadiya Roderique

Organizational behaviour and human resource management (2012-present)

Roderique, a ��οlaw graduate, is now pursuing a PhD at U of T. She was one of only five Black lawyers at a prestigious Bay Street law firm. Her time working in law, which she describes in a widely read Globe and Mail piece, left her feeling like she didn’t belong.

Questions that arose from that experience led her to quit her job and pursue a PhD at the Rotman School of Management.

Her thesis deals with parenthood. “I'm particularly interested in social relationships in the workplace,” she says. “We've observed gender differences in these social relationships, but we also have research that shows mothers are uniquely penalized in the workplace.”

She expects to defend her thesis this summer and has already lined up interviews with top consulting companies.

She thinks it’s unlikely she will end up in academia. “I see my role as a translator, someone who can make sense of the very important research people are doing and communicate that to the world, whether through journalism, consulting or policy development.”

Physical Sciences

Fault lines: ��������οresearch could protect cities in active earthquake zones

Why was there open water instead of ice north of Greenland this year? ��������οexpert has an answer

Tracing the steps of nearly 10,000 ��������οPhDs after graduation

Take a closer look at the data on the SGS website

Read about the survey in the Globe and Mail

Inmar Givoni

Helen Marshall

Emma Planinc

Michael Selvanayagam

Read more about the cloaking device in the Toronto Star

Hadiya Roderique

Fault lines: ��οresearch could protect cities in active earthquake zones

Why was there open water instead of ice north of Greenland this year? ��οexpert has an answer

Tracing the steps of nearly 10,000 ��οPhDs after graduation