Dr. Julia Gestrich

Research Interests

My research interests focus on the geophysical signals recorded during volcanic eruptions, specifically acoustic waves and electric field disturbances. Connecting the recorded signals to the observed dynamics using physics based, numerical and empirical model provides understanding how we can interpret the recorded signals and observed changed in the eruption remotely. Furthermore, I am interested in using analogous settings to explore certain signals with controlled parameters. In the past we have used experimental setups outdoors and in anechoic rooms for sound measurements as well as recorded both acoustic and electric measurements at various Geysers around the word to understand the signals sensitivity to the presence and movement of a fountain.

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Acoustic and Electric Signals of Geysers

Geysers provide natural analogues to lava fountains, allowing us to investigate eruption dynamics in accessible environments. We conduct measurement campaigns at Pōhutu (New Zealand), Strokkur (Iceland), Andernach (Germany), and even at the Jet d’Eau (Switzerland) to capture a diverse range of fountain behaviors. Using synchronized infrasound and audio microphones with high-speed video, we track the growth and rupture of water bulges that initiate geyser eruptions and model their acoustic sources as monopoles. To explore the associated electrical signals, we deploy a Biral Thunderstorm Detector to measure rapid changes in the local electric field caused by rising and widening water jets. By combining observational data with finite-element modeling and empirical relationships, we aim to invert for key physical parameters and establish links between fluid motion, sound generation, and electrical discharge during eruptive processes.

Running project

• VOLTA ERC consolidator grant

Gestrich, J.E., Cimarelli, C., Fee, D. et al. The acoustics of bulge rise and rupture at Strokkur geyser. Bull Volcanol 87, 82 (2025). https://doi.org/10.1007/s00445-025-01876-3

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Volcanic Jet Noise

Explosive volcanic jets produce powerful acoustic signals that encode eruption intensity and jet geometry. I developed a spectral fitting algorithm to fit jet noise similarity spectra of large and fine scale turbulence (LST and FST) to eruption data and published open source code for reproducible analysis. Applying jet noise scaling to the 2018 Kīlauea lava fountains allowed us to track changes in fountain height and width directly from acoustic spectra. To explore the role of particle load on the acoustic source we performed controlled shock tube experiments and sustained jetting experiments outdoors. By linking laboratory experiments, theory and natural observations we improve physical models that extract eruption parameters from sound and help refine remote monitoring of hazardous activity.

Gestrich, J. E. , Fee, D., Matoza, R. S., Lyons, J. J., Patrick, M. R., Parcheta, C., Kueppers, U., Cigala, V.,Dietterich, H. (2022). Lava fountain jet noise during the 2018 eruption of fissure 8 of Kīlauea volcano. Frontiers in Earth Science, Volume 10 - 2022. https://doi.org/10.3389/feart.2022.1027408

Lamb, O. D., Gestrich, J. E. , Barnie, T. D., Jónsdóttir, K., Ducrocq, C., Shore, M. J., Lees, J. M., Lee, S. J.(2022). Acoustic observations of lava fountain activity during the 2021 Fagradalsfjall eruption, Iceland. Bull Volcanol 84, 96 (2022). https://doi.org/10.1007/s00445-022-01602-3

Gestrich, J. E. , Fee, D., Matoza, R. S., Lyons, J. J., & Ruiz, M. C. (2021). Fitting Jet Noise Similarity Spectra to Volcano Infrasound Data. Earth and Space Science, 8(11), 1–16. https://doi.org/10.1029/2021ea001894

Publications