11:30 AM - 11:45 AM
[J03-2-04] Heterogeneous interseismic coupling along the Peruvian subduction zone and rigid motion of the Peruvian Sliver
Over 100 survey and continuous GPS measurements acquired in Peru between 2008 and 2013 provide new insights into the present-day crustal deformation of the Peruvian margin. The GPS velocity field together with information of compiled active faults reveal the rigid motion of the Peruvian Forearc Sliver extending from the trench to the boundary between the Western and Eastern Cordilleras, moving southeastward at a rate of 4-5 mm/yr relative to the stable South America. GPS data also reveal that tectonics in the Cordillera Oriental is dominated by 2-4 mm/yr of crustal shortening accommodated along the sub-Andean fold and thrust belt. In a local Peruvian Sliver reference frame the residual GPS velocity field reflects important lateral variations of the GPS gradients which attest for along-strike heterogeneous pattern of interseismic coupling along the megathrust. Heterogeneous interseismic coupling models indicate shallow and relatively weak coupling in northern Peru, deep and highly locked asperities distributed along the central and southern Peru coasts. These coupling patterns are consistent with past moderate tsunami-earthquakes in northern Peru and with the rupture areas of large and great megathrust earthquakes in central and southern Peru suggesting that seismic asperities might be persistent features of the subduction megathrust. Creeping segments correlate with the location of rupture limits of great past earthquakes and with the location of ridges and fracture zones supporting their role as seismic barriers to rupture propagation. In Central of Peru, where the great 1746 Mw~9.0 Lima-Callao occurred, the current interseismic moment deficit would suggest a recurrence time of at least 305 +- 40 yrs to reproduce a similar event. The occurrence of the 1940-2007 sequence of Mw~8.0 earthquakes may increase this recurrence time only by 30%.