Théa Ragon bio photo

Théa Ragon

Postdoc at Caltech - Earthquakes, faults and inverse problems


I am the GPS Chair’s Prize Postdoctoral Fellow at the California Institute of Technology. I completed my PhD in Geophysics at Géoazur, Université Côte d’Azur, in May 2019.

My research aims at better understanding the deformation of the shallow parts of the Earth on multiple temporal and spatial scales, from the displacement induced a few seconds to days before, during and after an earthquake to the long-term interaction of fault networks. I am particularly interested in modeling or simulating earthquakes and faults behavior.
These last few years, I focused on source estimation problems, using probabilistic approaches to decipher the robust characteristics, or the uncertainties, of our models. I also use stochastic methods to study recent large earthquakes. Finally, I am also interested in how faults interact with each other and how the characteristics of the medium around them can impact deformations.

You can find me in my office in the Seismological Laboratory building:
Office 262 | South Mudd building
Caltech Seismo Lab | GPS Division
1200 E. California Blvd., 252-21 | Pasadena, CA 91125, USA

You can also reach me via:
tragon (at)

Latest News

  • December 2022: Our two AGU sessions led by Zhe Jia and Elif Oral went extremely well! Many thanks to the presenters and many attendees, both online and in person! Special thanks to the OSPA judges. Recordings are available on the AGU website. If you cannot access a presentation, please reach out to me or another convener.

  • November 2022: I am presenting my results on the secondary zone of uplift at the 2022 SZ4D Community Meeting. Leah Langer is presenting a poster on our work on topography.

  • October 2022: I have been invited to give a seminar at ITES, Strasbourg (former EOST).

  • September 2022: I am presenting my results on the secondary zone of uplift measured after the 2010 Chile earthquake at the SCEC meeting. A version of the poster is available: PDF

  • July 2022: Seismica is open for submissions!!

  • June 2022: I have been invited to give a keynote on The future of finite-fault modeling: how critical are structural heterogeneities? at the CIG Crustal Deformation Modeling Workshop, Golden, USA.

  • June 2022: Pylith v3 is out!

  • June 2022: Our session proposals for AGU 2022 have been accepted! Please consider submitting abstracts to:
    • S001: Advancements in imaging earthquake source processes co-convened with Zhe Jia (UCSD IGPP), Ryo Okuwaki (University of Tsukuba) and Elisa Tinti (Università La Sapienza). Invited speakers: Federica Paglialunga, EPFL, and Kurama Okubo, NIED.
    • S006: Complexities of fault rupture and their implications for the joint studies of earthquake source physics and ground motion, co-convened with Elif Oral (Caltech), Ahmed E. Elbanna (University of Illinois at Urbana Champaign) and Alice Gabriel (Ludwig-Maximilians-Universität). Invited speakers: Shanna Chu, Brown University and Elias R. Heimisson, ETH Zurich.
  • May 2022: I am pleased to announce I have been awarded an AGU 2021 Editors’ Citation for Excellence in Refereeing

  • March 2022: I gave an invited keynote at the GeoPRISMS Workshop on Deformation at plane boundaries, about On and off-fault deformation: similar research directions for subduction zones and rift systems?

  • January 2022: I have been offered the position of co-Chair of the Standards and Copy Editing Team, and handlind editor, for Seismica, a community-led diamond open access journal for earthquake sciences!

  • December 2021: Our AGU session on the earthquake source has been amazing! Many thanks to the presenters and many attendees, both online and in person, that made it possible! Recordings are available on the AGU website until February 2022. If you cannot access a presentation, please reach out to me, another convener or the presenter.

  • November 2021: Our paper on the evolution of the northern Turkana Depression (EARS), as seen from the interpretation of seismic reflection and field analyses, is now published in EPSL! Key result: we show that a regional-scale migration of the locus of brittle deformation promotes the concomitant development of post-tectonic (sag) and syn-tectonic deformations.

  • November 2021: My recent seminar at Isterre, Grenoble, has been recorded: video is here, with the first few minutes missing

  • September 2021: Glad to have given the first seminar of the year at the geological lab of ENS Paris!

  • June 2021: Our session proposal for AGU 2021 has been accepted! Please consider submitting abstracts to S023- State-of-the-art observations and modeling of earthquake source processes, convened with Alice Gabriel, Elisa Tinti and Yoshihiro Kaneko.

  • June 2021: I am participating to the Pylith 2021 Hackathon!

  • March 2021: I gave a Mardi Séisme seminar at Géoazur, Nice. You can find the recording of my talk on their youtube chanel: How to hamper the effect of Earth’s structure approximations on on-fault deformation estimates?

  • January 2021: Our work on uncertainties in fault geometry is amongst the 14 most cited articles of GJI in 2020!