Geology & Geophysics Editors' Highlights

The Highs and the Lows of Megathrust Earthquakes

Why does low-frequency energy come from the shallow part of ruptures, and the high frequencies from deep?

Source: AGU Advances


Earth’s largest earthquakes happen on subduction zone megathrusts, and destructive tsunamis often accompany strong shaking. These earthquakes almost always have a puzzling seismic signature; the shallow parts of megathrust ruptures cause tsunamis but mostly emit low-frequency seismic waves that cause less damaging shaking. However, the deeper parts of the ruptures excite high-frequency waves that are especially dangerous to the built environment. Past studies have suggested that this dichotomy results from different fault properties with depth. However, Yin and Denolle [2021] show that rupture characteristics are very different nearer to the Earth’s surface than at greater depth, which causes the change in seismic signatures. The authors note that their use of more realistic Earth models enables them to capture complex interactions between seismic waves and near surface geology in dynamic rupture simulations that reproduce observations.

Citation: Yin, J. & Denolle, M. [2021]. The Earth’s surface controls the depth-dependent seismic radiation of megathrust earthquakes. AGU Advances, 2, e2021AV000413.

—Tom Parsons, Editor, AGU Advances

Text © 2021. The authors. CC BY-NC-ND 3.0
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