Adjunct tomography sheds light on the complexity of the Hikurangi margin

Editors’ Highlights are summaries of recent articles written by AGU’s journal editors.
Source: Journal of Geophysical Research: Solid Earth

The locked-to-creeper transition of seismic coupling northward along New Zealand’s Hikurangi margin has long puzzled geoscientists.

In a new study, Chow et al. [2022] using a sophisticated waveform inversion method along with data from numerous regional earthquakes to image structure along the margin at depths of 30 kilometers in unprecedented detail. The images indicate bathymetric structures that mirror those observed in analog sand table experiments and suggest that progressive subduction of seamounts is weakening the upper plate.

This weakening in turn renders the plate boundary less able to store or store elastic deformation, and thus provides an explanation for the curious transition of coupling and segmentation observations in slow-sliding earthquakes.

Citation: Chow, B., Kaneko, Y. and Townend, J. (2022). Evidence of deeply subducted lower plate seamounts at the Hikurangi subduction margin: implications for seismic and aseismic behavior. Journal of Geophysical Research: Solid Earth127, e2021JB022866.

—Michael Bostock, editor, Journal of Geophysical Research: Solid Earth

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Sharon D. Cole