Keisuke Yoshida

Associate Professor · Graduate School of Science, Tohoku University

I study how and why earthquakes happen. Using observations, I connect the state of faults — stress, strength, fluids, and loading — to how seismicity behaves as a population, and to how individual earthquakes start, grow, and stop.

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My work addresses two linked questions: where and when earthquakes occur, and how each rupture starts, grows, and stops.

Stress and fluids. Stress changes after large earthquakes constrain the strength of the crust (GRL 2012; JGR 2014). After the 2011 Tohoku-oki earthquake, inland swarms started where shear stress had decreased, isolating the effect of fluids weakening faults (JGR 2016, 2017, 2018). In the Noto Peninsula, updip fluid flow triggered the 2023 Mw 6.2 Suzu earthquake (GRL 2023).

Resolving ruptures. I resolve rupture patterns down to small earthquakes: asymmetric rupture is common (Geosci. Lett. 2019), a database of moment-rate functions for 1,736 earthquakes (GJI 2023), and diverse source complexity even at Mw 3.3–5.0 (SRL 2024).

Growth and arrest. Repeating earthquakes off Miyagi show that rupture patterns respond to loading rate, and that the size of the initial rupture decides whether it cascades (GRL 2025; JGR 2023). This frames my analyses of the 2025 Aomori-oki and Sanriku-oki sequences.

Open data. Relocated hypocenters, focal mechanisms, stress fields, rupture models, repeater catalogs, and moment-rate functions are on the data page.

Highlights

2026 · GRL

The 2025 Mw 7.6 Aomori-oki megathrust sequence and a slip-parallel seismic belt to the trench.

2026 · GRL

Evolution of coupled seismic–aseismic slip during the 2025 Mw 6.8 Sanriku-oki sequence.

Guest editor

EPS special issue on the 2025 Mw 7.6 off-Aomori earthquake — open until 31 Mar 2027.

Featured

Spatiotemporal migration of the Noto earthquake swarm — Spatiotemporal migration of the Noto Peninsula earthquake swarm.From Yoshida et al. (2023, JGR).

Source time functions across azimuth, revealing rupture directivity and complexity.From Yoshida & Kanamori (2023, GJI).

Repeating large earthquakes rupturing the same fault patch over time — a direct expression of the earthquake cycle.From Yoshida et al. (2022, JGR).

Depth-dependent rotation of the crustal stress field.From Yoshida et al. (2014, JGR).

Recent publications

Yoshida, K., 2026, Evolution of Coupled Seismic-Aseismic Slip During the 2025 Mw 6.8 Sanriku-Oki, Japan, Megathrust Sequence, Geophysical Research Letters, 53, e2026GL121704, doi:10.1029/2026GL121704.
Yoshida, K., M. Uno, D. Bassett, 2026, The 2025 Mw 7.6 Aomori-Oki Megathrust Sequence and a Slip-Parallel Seismic Belt to the Trench, Geophysical Research Letters, 53, e2026GL122361, doi:10.1029/2026GL122361.

All publications →

Related datasets

Yoshida, K., M. Uno, D. Bassett, 2026, Data for the 2025 Mw 7.6 Aomori-Oki Earthquake Sequence: Relocated Hypocenters and Rupture Models, Zenodo, doi:10.5281/zenodo.19963531.
Yoshida, K., 2026, Data for the 2025 Mw 6.8 and Mw 6.4 Sanriku-Oki Earthquakes: Relocated Hypocenters, Rupture Models, and Strainmeter Data, Zenodo, doi:10.5281/zenodo.19383821.

Research interests