Geophysics

Allowing faults out of lock-up

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Science  31 Jul 2015:
Vol. 349, Issue 6247, pp. 491-492
DOI: 10.1126/science.349.6247.491-d

Relict microatoll on southeastern island of Simeulue, Sumatra

PHOTO: ARON J. MELTZNER/EARTH OBSERVATORY OF SINGAPORE

The crust around a locked, earthquake-prone fault responds to the two sides pulling in opposite directions by bowing and bulging over time. Meltzner et al. and Wesson et al. challenge a common assumption that this deformation progresses mostly in a uniform, linear way. Deformation shows up in seafloor bathymetry, which changes abruptly for both Sumatra and Isla Santa Maria, Chile, over a seismic cycle. Periods during which the fault is weakly locked explains the non-uniform behavior. Quantifying the effect clarifies subduction zone mechanics, which may require updating estimates of earthquake hazard.

Quat. Sci. Rev. 10.1016/j.quascirev.2015.06.003 (2015); Nat. Geosci. 10.1038/ngeo2468 (2015).

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