No large earthquakes in fully exposed subducted seamount

Guillaume Bonnet (1) , Philippe Agard (1) , Samuel Angiboust (2) , Marc Fournier (1) , J. Omrani (3)

1 iSTeP - Institut des Sciences de la Terre de Paris
2 IPGP - Institut de Physique du Globe de Paris
3 Geological Survey of Iran

Bathymetric highs on the ocean floor ultimately sink into highly seismic subduction zones, raising vigorous debates on their potential to trigger or arrest large earthquakes (Mw > 7.5). Many geophysical and seismological studies addressing this problem meet penetration and/or resolution issues and deal with only the most recent earthquakes. We herein present the missing piece of the puzzle with the time-integrated field and petrographic record of a unique, almost intact subducted seamount cropping out along a fossil subduction interface. We document seamount buildup and subduction down to ~30 km, and we show that this seamount did not behave as a large earthquake asperity and may have acted as a barrier.

Domaines: Planète et Univers [physics]

Guillaume Bonnet, Philippe Agard, Samuel Angiboust, Marc Fournier, J. Omrani. No large earthquakes in fully exposed subducted seamount. Geology, 2019, 47 (5), pp.407-410. ⟨10.1130/G45564.1⟩. ⟨insu-03978986⟩