Benjamin R. Idini Zabala

I am a Planetary Geophysics PhD student at Caltech working under the mentorship of Professor David Stevenson. My scientific interests are broad and involve geophysical phenomena on Earth and other planets in the Solar system. Part of my research includes a range of aspects related to earthquakes: quantification of ground motion, fault slip models derived from remote sensing, and exposing the links between fault structure and rupture propagation. My most recent scientific activities are concentrated on studying the tidal response of Jupiter to the gravitational influence of the Galilean moons.

Email: bidiniza at caltech dot edu

Office: 162 South Mudd.

research

Jupiter

dynamical tides · spectral collocation · normal modes

The interior structure of Jupiter is intimately related to our understanding of the formation of planets in the Solar system. As the Moon does on Earth, the Galilean satellites Io, Europa, and Ganymede raise tidal bulges on Jupiter causing observable disturbances to its gravitational field. We are using the Juno mission measurements of Jupiter's gravitational field to learn more about the interior of this gas giant.

Jupiter's South pole as revealed by Juno (NASA/JPL-Caltech/SwRI/MSSS).

Earth

slow earthquakes · rupture dynamics · numerical simulations

Earthquakes are cracks that propagate along faults, changing the landscape and the mechanical properties of the surrounding material. We have used simple models of the mechanical properties of a fault zone to study the interactions between the damaged material and the kinematics of crack propagation. We found that damage zones around faults can induce back-propagating rupture fronts, a complex pattern of rupture propagation that has been observed in Japan and Cascadia. Moreover, our simple fault-zone model induces a pulse-like mode of rupture propagation, a rather common characteristic of large earthquakes that simple models without fault zones struggle to reproduce. (Idini & Ampuero 2019).

Bayesian inversion · MCMC sampling · radar interferometry

On the observational side, I have used radar interferometry together with a Bayesian framework centered on Monte Carlo Markov Chain sampling to infer a slip model for the 2019 Ridgecrest earthquake sequence, the largest seismic event in Southern California in the last 20 years. In collaboration with scientists and engineers from Caltech and JPL, we have revealed the complex structure of this large event with unprecedented detail after synthetizing the analisis of large amounts of remote sensing and seismic data (Ross et al. 2019).

ground motion · Chilean seismicity · signal processing

As part of my early education in earthquake engineering, I developed an empirical quantification of the ground motion expected during large earthquakes in Chile using seismic data from regional accelerometers (Idini et al. 2016).

Valdivia residents explore a crack caused by the 1960 Chile earthquake (STF/AFP/Getty).

papers

[3] Idini, B. & Ampuero J.-P., 2019, Fault-zone damage promotes pulse-like rupture and rapid-tremor-reversals, EarthArXiv:v8xr2.

[2] Ross, Z., Idini, B., Jia, Z., et al., 2019, Hierarchical interlocked orthogonal faulting in the 2019 Ridgecrest earthquake sequence, Science, 366, 6463.

[1] Idini, B., Rojas, F., Ruiz, S., & Pastén C., 2016, Ground motion prediction equations for the Chilean subduction zone, Bull. Earthq. Eng., 15, 5.