Academic Research

Exploring Earth's interior through computational geophysics

Research Focus

Mantle Convection Visualization

Visualization of mantle flow and hotspot interactions

My research in computational geophysics focuses on developing advanced particle-tracking methods in 4D global mantle convection models. By integrating seismic tomographic data with geochemical signatures, I aim to clarify the origin and evolution of hotspot-related chemical anomalies through reconstructing mantle flow across geological timescales.

Key research areas include:

  • Reconciling hotspot geochemistry with mantle dynamics through particle tracking
  • Analyzing the DUPAL geochemical anomaly in the South Atlantic and Southwest Indian Oceans
  • Developing C++ implementations for particle tracking methods in mantle convection
  • Testing models for three-component mantle heterogeneity

Collaborations

I work closely with the Institute of Global Physics in Paris, France, combining computational approaches with field observations to create comprehensive models of Earth's internal dynamics.

Education

2020 - Present

PhD Candidate, Geologic Sciences

University of Florida, Gainesville, FL

Thesis: Reconciling Hotspot Geochemistry with Mantle Dynamics through Particle Tracking

Advisor: Professor Alessandro Forte

Coursework/Research in conjunction with the Institute of Global Physics, Paris

2019

Bachelor of Arts, Astronomy and French Literature

University of Florida, Gainesville, FL

Minors: Physics, Geology, Music Performance

Spring 2016 – Fall 2016

Year Abroad

Université Paris Diderot & Institut Catholique de Paris, Paris, France

Studied Literature, Astronomy, and conducted research in Second Language Acquisition

Publications & Presentations

2025

Playing with Edges: The Influence of Arbitrary Definitions on Hotspot–LLSVP Correlations

Johnston, G., Liu, S., Forte, A., & Glisovic, P.

EGU General Assembly 2025, Vienna, Austria

DOI: 10.5281/zenodo.14740086

This study investigates how different definitions of Large Low Shear Velocity Province (LLSVP) boundaries affect correlations with hotspot distributions. Using particle tracking in 4D mantle convection models, we demonstrate that arbitrary boundary definitions can lead to significantly different conclusions about hotspot-LLSVP relationships.

2024

Towards a New Geodynamic and Geochemical Reconciliation of the Origin of the DUPAL Geochemical Anomaly in the South Atlantic and Southwest Indian Oceans

Johnston, G., Forte, A., Glisovic, P., Chauvel, C., Farnetani, C., & Robert, B.

Ada Lovelace Workshop on Modelling Mantle and Lithosphere Dynamics, Sète, France

DOI: 10.5281/zenodo.14706576

The DUPAL geochemical anomaly presents a longstanding puzzle in mantle geochemistry. This work presents a new integrated model combining particle tracking in time-dependent mantle flow simulations with isotopic data to explain the origin and persistence of the DUPAL signature in the South Atlantic and Southwest Indian Oceans.

2022

Testing Models for Three-Component Mantle Heterogeneity as Recorded in Compositions of Lavas from the Off-Axis 8°20' N Seamount Chain

Anderson, M., Perfit, M., Graham, D. W., & Johnston, G.

Goldschmidt 2022

DOI: 10.46427/gold2022.12742

This study examines lava compositions from the Off-Axis 8°20' N Seamount Chain to test models of three-component mantle heterogeneity. The results provide insights into the complex interactions between depleted and enriched mantle components in mid-ocean ridge settings.

2021

Time-Dependent Convective Modelling of DUPAL Signatures in the South Atlantic: Implications for LLSVP Source Region

Johnston, G., Forte, A., & Glisovic, P.

AGU Fall Meeting 2021, New Orleans, LA

ID: DI44B-07, Bibcode: 2021AGUFMDI44B..07J

Using time-dependent convective modeling, this study explores the relationship between DUPAL geochemical signatures in the South Atlantic and the Large Low Shear Velocity Province (LLSVP) at the core-mantle boundary. The results suggest a complex history of mantle flow and compositional evolution that connects deep mantle structures to surface geochemical anomalies.

Projects & Hackathons

ASPECT Hackathon

ASPECT Hackathon

May 2024

Advanced Solver for Planetary Evolution, Convection, and Tectonics

  • Developed C++ implementations for particle tracking methods in mantle convection
  • Evaluated alternative Runge–Kutta schemes, including the 3/8th method
  • Performed cost-benefit analysis and tested feasibility of embedded methods in ASPECT
View Project Details
Particle Tracking Methods

Advanced Particle Tracking in Mantle Convection

2021 - Present

Development of numerical methods for tracking particles in 4D flow fields

  • Created algorithms for efficient tracking of compositional heterogeneities in time-dependent flow fields
  • Implemented backward-in-time tracking for source determination
  • Developed visualization tools for 4D particle trajectories
View Project Details
Star Formation Research

Galactic Census of High and Medium-mass Protostars (CHaMP)

2018 - 2019

Undergraduate research project in star formation

  • Developed Python code for near-infrared photometry and photometric analysis
  • Contributed to the census of protostars under Dr. Peter Barnes
  • Analyzed data from multiple telescope observations
View Project Details

Technical Skills

Programming Languages

Python
Highly Fluent
C++
Proficient
Fortran
Competent

Software & Tools

ASPECT
Advanced
GMT (Generic Mapping Tools)
Proficient
Scientific Data Visualization
Expert

Languages

English
Native
French
Professionally Fluent

Awards & Grants

Grinter Award

2024

$4,000

Awarded for excellence in graduate research and academic achievement.

Sinks Fellowship

2022

$3,250

Summer research fellowship for exceptional graduate students in the Geosciences.

Download My CV

For a complete overview of my academic background, research experience, and publications.

Download CV