Britta Jensen, PhD

Associate Professor, Faculty of Science - Earth & Atmospheric Sciences Admin

Contact

Associate Professor, Faculty of Science - Earth & Atmospheric Sciences Admin
Email
bjjensen@ualberta.ca
Phone
(780) 492-3430
Address
3-02 Earth Sciences Building
11223 Saskatchewan Drive NW
Edmonton AB
T6G 2E3

Overview

Area of Study / Keywords

Quaternary geology paleoenvironments volcanology tephrochronology


About

Welcome to my website.

I am a geologist who works mostly on Quaternary time-scales. I specialize in tephrochronology, which is the study of volcanic ash deposits (tephra) and how they can be used to date and correlated stratigraphic sequences. I also am interested in the extensive aeolian deposits in the interior of Alaska and the Yukon.

A bit of background. I completed my BSc in Geology at Simon Fraser University in Burnaby British Columbia and my MSc and PhD here at the University of Alberta. I completed an NSERC post-doctoral fellowship at Queen's University Belfast in the UK and went on to the Royal Alberta Museum to work in the Quaternary Environments group. As of July 1 2017 I rejoined the Department of Earth and Atmospheric Sciences as an Assistant Professor.






Research

Research interests in volcanic ash:

Volcanic ash deposits found in different environments (e.g. marine, lake, terrestrial, ice) can provide insights into the paleoenvironmental records preserved in those environments and often offer important chronological control.

Distal (>10 km or so from their source) ash deposits can also tell us an important story about volcanic activity from a specific centre or region, supplementing proximal deposits that can often be removed by glaciation or subsequent eruptions.

Understanding eruption histories of volcanoes is important from several different perspectives. We are interested in changes in eruption frequency through time to help us understand the external controls (tectonic, glacial) that might help control the rate of eruptions. There are also potential impacts on climate related to increases in activity. Developing eruptions histories are also integral to understanding the hazard a particular volcano or region may pose to people.

Documenting distal deposits such as their distribution, grain size, and morphology also provides important field data for the ongoing efforts in building models that aim to accurately model ash fall.

Research interests in stratigraphy:

My research has largely been based in eastern Beringia, the unglaciated regions of Yukon and Alaska, which contain extensive deposits of aeolian deposited silts, known as loess.

Loess deposits are fascinating because of they are often linked to glacial cycles and are excellent paleoenvironmental archives. In Alaska these deposits can be as old at ~ 3 million years, providing one of the few records of terrestrial sedimentation for the entire Quaternary.

I am interested in the paleomagnetic characteristics, geochemistry, stratigraphy and sedimentology of these loess deposits and the insights into the Quaternary paleoenvironmental record of the north they provide.


Teaching

I regularly teach EAS 100/201 in the Fall Semester and EAS 110 (Field School) and EAS 457 in the Winter.

Announcements

Research opportunity on Mount St. Helens May 18th 1980 eruption

Graduate student, MSc or PhD

Please note this project will be supervised by prof. Pierre-Simon Ross (https://inrs.ca/en/research/professors/pierre-simon-ross/) and co-supervised by prof. Britta Jensen (University of Alberta, https://apps.ualberta.ca/directory/person/bjjensen). The selected candidate will be based at INRS’ Eau Terre Environment research centre in downtown Quebec City, Canada (https://inrs.ca/en/inrs/research-centres/eau-terre-environnement-research-centre/). Motivated candidates should immediately submit their resume, a cover letter, and the names and complete coordinates of three referees to Pierre-Simon Ross at pierre-simon.ross@inrs.ca.

INFORMATION: 

Mount St. Helens (MSH) in Washington State (Cascades arc) is an active stratovolcano posing a significant natural hazard to the USA and Canada. The last major explosive eruption on May 18, 1980 killed over 50 people and had very destructive effects still visible over 40 years later. In fact, it was one of the largest and destructive eruptions of the 20th century. The 1980 eruption began at 08:32 AM local time as the summit of the volcano collapsed in a giant landslide. Magma that resided just under the summit, known as a cryptodome, and the surrounding hydrothermal system, were decompressed. This triggered an extremely large and violent lateral blast, i.e., a hot cloud of gas, ash and large fragments that accelerated down the volcano at speeds up to 600 km/h and destroyed forests across 600 km2, an area larger than the island of Montreal. A vertical eruptive column (the plinian phase) began rising at ~9 AM and remained strong until ~5 PM.


The 1980 eruption of MSH is an exceptional opportunity to improve our current understanding of eruption dynamics and processes. The eruptive style and the magma fragmentation process both varied significantly during the day. This means that ash with different characteristics was generated at various times, and it can be sampled in the proximal to medial environment. This ash can also be compared with the ultradistal record of the eruption, consisting of cryptotephra in peat bogs, which we will try to find in Quebec, thousands of kilometers away from the volcano, as part as a collaboration with Université de Montréal biogeography researchers. Ash samples will be analyzed at INRS and the University of Alberta using a recently developed international standardized protocol. While modelling predicts that ash likely fell on Quebec, we still don’t fully understand how such long distance transport is possible, and the research will also address this question.


Funding is available for two years, which is enough for a MSc. In the case we recruit a PhD student, the candidate will be expected to find an external scholarship to finance part of the remuneration costs, for example:

  • NSERC PGS D for Canadians (https://www.nserc-crsng.gc.ca/Students-Etudiants/PG-CS/BellandPostgrad-BelletSuperieures_eng.asp)
  • FRQNT doctoral training (for Quebec residents) or PBEEE (for foreign students) (https://frq.gouv.qc.ca/en/scholarships-and-grants/?funds-type=nature-et-technologies-en&program=scholarships-and-training-courses&research-status=student)

The candidate will have university training in geology, earth sciences or geological engineering, with an average grade meeting the INRS admission standards. In the case of a PhD candidate, the person’s file must have a strong likelihood of qualifying for one of the external grants mentioned above, which implies a very high average grade and a publication record. Scientific writing skills are essential and so is a passion for science and discovery.


The project will start during the Fall semester (September 2023) or the winter semester (January 2024).