FN Archimer Export Format
PT J
TI Subducted oceanic relief locks the shallow megathrust in central Ecuador
BT 
AF COLLOT, Jean-Julien
   SANCLEMENTE, Eddy
   NOCQUET, Jean-Mathieu
   LEPRETRE, Angelique
   RIBODETTI, Alessandra
   JARRIN, Paul
   CHLIEH, Mohamed
   GRAINDORGE, David
   CHARVIS, Philippe
AS 1:1,2,3;2:1,4;3:1,2;4:1;5:1;6:2;7:1;8:5;9:1;
FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;
C1 Univ Cote Azur, IRD, CNRS, OCA,Geoazur, Valbonne, France.
   Escuela Politec Nacl, Inst Geofis, Quito, Ecuador.
   Minist Higher Educ Sci Technol & Innovat Republ E, Prometeo Project, Guayaquil, Ecuador.
   Escuela Super Politecn Litoral, Guayaquil, Ecuador.
   Univ Bretagne Occidentale, Lab Domaines Ocean, Plouzane, France.
C2 UNIV NICE, FRANCE
   INST GEOFISICO, ECUADOR
   MINIST HIGHER EDUC SCI TECHNOL & INNOVAT REPUBL E, ECUADOR
   ESPOL, ECUADOR
   UBO, FRANCE
UM LGO
IF 3.482
TC 58
UR https://archimer.ifremer.fr/doc/00638/75038/75652.pdf
   https://archimer.ifremer.fr/doc/00638/75038/75653.pdf
LA English
DT Article
DE ;seamount subduction;interseismic coupling;seismic imaging;slow slip event;megathrust earthquake
AB Whether subducted oceanic reliefs such as seamounts promote seismic rupture or aseismic slip remains controversial. Here we use swath bathymetry, prestack depth-migrated multichannel seismic reflection lines, and wide-angle seismic data collected across the central Ecuador subduction segment to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, low height-to-width ratio, multipeaked, sediment-bare, shallow subducted oceanic relief. Owing to La Plata Island and the coastline being located, respectively, similar to 35km and similar to 50-60km from the trench, GPS measurements allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its highly jagged topography, the absence of a subduction channel, and a stiff erosive oceanic margin are found to be long-term geological characteristics associated with the shallow locking of the megathrust. Although the size and level of locking observed at the subducted relief scale could produce an M-w >7+ event, no large earthquakes are known to have happened for several centuries. On the contrary, frequent slow slip events have been recorded since 2010 within the locked patch, and regular seismic swarms have occurred in this area during the last 40years. These transient processes, together with the rough subducted oceanic topography, suggest that interplate friction might actually be heterogeneous within the locked patch. Additionally, we find that the subducted relief undergoes internal shearing and produces a permanent flexural bulge of the margin, which uplifted La Plata Island. Plain Language Summary Subducted seamounts play an important but still uncertain role in earthquake rupture processes, as seamounts are considered to subduct either aseismically or seismically. We use marine geophysical data across the central Ecuador convergent margin to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, shallow subducted oceanic relief of the Carnegie Ridge. New GPS measurements collected on La Plata Island and along the Ecuador coast allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its rough topography and the stiff oceanic Ecuador margin are found to be long-term geological characteristics associated with the shallow locking of the plate interface. Although the size and level of locking observed at the subducted relief scale could produce an M-w >7+ event, no large earthquake but frequent slow slip events and associated seismic swarms occurred within the locked patch. These transient processes together with the rough subducted oceanic topography support the view of a heterogeneous interplate frictional pattern within the locked patch. On a regional scale, the subduction of the oceanic relief has deformed the Ecuador margin and uplifted La Plata Island. 
PY 2017
PD MAY
SO Journal Of Geophysical Research-solid Earth
SN 2169-9313
PU Amer Geophysical Union
VL 122
IS 5
UT 000403465600002
BP 3286
EP 3305
DI 10.1002/2016JB013849
ID 75038
ER

EF