Hi! I am a UC President's Postdoctoral Fellow exploring the interiors of giant planets and icy satellites in the outer solar system. I am originally from Chile, a land of powerful telescopes and large earthquakes.
Ph.D. Planetary Science, Caltech 2022
M.S. Geophysics, Caltech 2019
M.S.E. Earthquake Engineering, Universidad de Chile 2016
B.S.E. Civil Engineering, Universidad de Chile 2013
Tidal theory of the gas giant planets
Since 2016, the Juno spacecraft has been orbiting Jupiter and collecting a unique data set of Jupiter's tidal Love numbers, namely the tidal response of Jupiter to the masses of the Galilean satellites in orbit around Jupiter. In a pioneering work, I further developed the theory of dynamical tides applied to gas giant planets (Idini and Stevenson, 2021), a body of knowledge that had not been touched since 1984 (Vorontsov+, 1984). In this theoretical rebirth of Jovian dynamical tides, I showed that the tidal Love number k2 measured by Juno was compatible with a modification on the tidal flow produced by the Coriolis force in a rapidly rotating gas giant planet (Idini and Stevenson, 2021). Paired with the Juno observation, these theoretical results constitute the first detection of dynamical tides in a gas giant planet.
Additional Love numbers were reported by Juno after the arrival of the k2 retrievals. The high-degree tides represented in k42 are not only harder to observe, but are also harder to interpret. I applied first-order perturbation theory to develop a fully analytical theory to illuminate the interpretation of k42 (Idini and Stevenson, 2022a). This theory shows how the oblate figure of Jupiter resulting from rapid rotation couples the tides to the rotational response, resulting in an order of magnitude enhancement in k42 (Wahl+, 2020, Idini and Stevenson, 2022a). The resulting k42 enhancement gives rise to an anomaly after comparing models with the Juno k42 observation.
Jupiter's South pole as revealed by Juno (NASA/JPL-Caltech/SwRI/MSSS).
The tidal imprint of a dilute core hosted in Jupiter
In the traditional view of gas giant planet interiors, an envelope of H-He fluid covers a compact core of rocky and icy material. This traditional view nicely emerges from the standard model of planet formation via core accretion. However, even to this day, no geophysical evidence exists to validate the traditional view.
The zonal gravitational field (i.e., non tidal) observed by Juno suggests that Jupiter hosts a dilute core that may extend as far as ~0.6R (Militzer+, 2022). A less extended dilute core could also explain the data when using a different equation of state for the H-He fluid (Miguel+, 2022). Avoiding the uncertainties related to the equation of state, I used Jovian dynamical tides and normal modes to show that internal gravity waves trapped in an extended dilute core (~0.7R) reconcile the anomaly in Juno's k42 observation (Idini and Stevenson, 2022b). This proposed scenario invokes a resonance between Jupiter's internal gravity waves and the orbital motion of the satellite Io.
What kind of core does Jupiter have? (Idini 2022)
Theoretical and computational earthquake mechanics
The nucleation, propagation, and arrest of earthquakes remains a fundamental but still unsolved problem in geophysics. Motivated by seismological and geodetic observations of rock damage near fault zones, I expanded a spectral boundary integral method (Luo+, 2017) to numerically model earthquake cycles and rupture propagation in an elastic medium that accounts for the damaged rock that surrounds fault zones. My work has identified a new mechanism to earthquake pulses, a common rupture propagation mode observed during large destructive earthquakes (Idini and Ampuero, 2020).
Spatiotemporal evolution of slip velocity in the characteristic event of an intact homogeneous medium, a low-velocity fault zone, and an intact homogeneous medium with ten times smaller nucleation length.
Earthquake ground-motion characterization
Active seismic regions require accurate characterizations of earthquake ground motion to minimize human and material losses during potentially destructive events. I developed a statistical model to estimate the ground motion produced during destructive earthquakes in Chile that is routinely used in seismic hazard studies (Idini+, 2017).
Valdivia residents explore a crack caused by the 1960 Chile earthquake (STF/AFP/Getty).
Spaceborne reconstruction of earthquake sources
After the 2019 Ridgecrest earthquake that ended ~20 yr of seismic quiescence in California, I produced a reconstruction of coseismic fault slip using Bayesian methods, satellite radar maps of surface deformation, and GPS displacements (Ross+, 2019). This model has become a prime reference to the characterization of this large and complicated earthquake.
(A) Bayesian coseismic slip reconstruction of the 2019 Ridgecrest earthquake. (B) Line-of-sight coseismic ground displacement obtained from the ALOS-2 spacecraft.
(11) Idini, B., Ruiz, S., Ampuero., J-P., Rivera, E, & Leyton, F. (in prep). High-frequency strong ground motion along the plate boundary in Northern Chile.
(10) Idini, B. & Stevenson D.J. (2022). The gravitational imprint of an interior-orbital resonance in Jupiter-Io, The Planetary Science Journal.
(9) Idini, B. & Stevenson D.J. (2022). The lost meaning of Jupiter's high-degree Love numbers, The Planetary Science Journal.
(8) Idini, B. & Stevenson D.J. (2021). Dynamical tides in Jupiter as revealed by Juno, The Planetary Science Journal.
[PDF] [Press1] [Press2]
(7) Erickson, B., Jiang, J., et al., including Idini, B. (2020). The community code verification exercise for simulating sequences of earthquakes and aseismic slip (SEAS), Seismological Research Letters.
(6) Idini, B. & Ampuero J.-P. (2020). Fault-zone damage promotes pulse-like rupture and back-propagating fronts via quasi-static effects, Geophysical Research Letters.
[PDF] [Supporting Information] [Software] [Press]
(5) Ross, Z., Idini, B., Jia, Z., et al. (2019). Hierarchical interlocked orthogonal faulting in the 2019 Ridgecrest earthquake sequence, Science.
[Supplementary Material] [Software] [Press]
(4) Gurnis, M., et al., including Idini, B. (2019). Incipient subduction at the contact with stretched continental crust: The Puysegur Trench, Earth and Planetary Science Letters
(3) Leyton, F., Pastén, C., Ruiz, S., Idini, B., & Rojas, F. (2018). Empirical site classification of CSN network using strong‐motion records. Seismological Research Letters.
(2) Luo, Y., Ampuero, J. P., Galvez, P., Van den Ende, M., & Idini, B. (2017). QDYN: a Quasi-DYNamic earthquake simulator (v1. 1). Zenodo.
(1) Idini, B., Rojas, F., Ruiz, S., & Pastén C. (2017). Ground motion prediction equations for the Chilean subduction zone, Bulletin of Earthquake Engineering.