Research

1. Mechanics of geometrically complex faults

Natural faults’ geometry show irregularity at all spatial scales. I am studying how through physics-based numerical simulations. As my master thesis, I addressed how an earthquake starts on a fault that has fractal geometry (Ozawa et al. 2019, GRL). During my PhD course, I demonstrated that a realistic aftershock sequence can be reproduced by numerical simulations that account for a nonplanar main fault and numerous subsidiary faults (Ozawa & Ando, 2021, JGR). I also worked on how rupture termination occurs at fault bends (Ozawa et al. 2023, EPSL) .

2. Effects of fault zone fluid transport on the earthquakes and aseismic slip in the subduction zones

As postdoc, I am investigating the role of fluid flow on the earthquake and slow slip, especially in the subduction zones. I explore the effect of permeability changes (fault-valving) on the stability of steady fault sliding. 

3. Efficient computational methods for sequence of earthquakes and aseismic slip (SEAS)

Earthquake sequence simulations are becoming a major tool to study the behavior of the fault from seconds (single earthquake rupture) to millenia (interseismic period) time scales. I am developing a high performance computational code for SEAS with computational scientists (Ozawa et al. 2023, GJI). I have participated in a cross-validation project of SEAS codes under Sourthern California Earthquake Center (Jiang et al., 2022, JGR, Erickson et al, 2023, BSSA). I was also involved in developing spectra BIEM that applicable to nonplanar faults (Romanet and Ozawa, 2022, BSSA). Our code HBI is open source and freely available at github.