Revisiting the North Chile seismic gap segmentation using GPS-derived interseismic coupling

摘要: No major earthquake occurred in North Chile since the 1877 M w 8.6 subduction that produced a huge tsunami. However, geodetic measurements conducted over last decade this area show upper plate is actually deforming, which reveals some degree of locking on interface. This accumulation elastic deformation likely to be released future earthquake. Because long elapsed time and rapid (thought 6–7 cm/yr), many consider mature seismic gap where due hazard high. We present new Global Positioning System (GPS) velocity field, acquired between 2008 2012, describes detail interseismic 18°S 24°S. invert for coupling distribution Nazca-South America interface using modelling. Our require that, at these latitudes, 10 12 mm yr−1 (i.e. 15 per cent whole convergence rate) are accommodated by clockwise rotation an Andean block bounded East subandean fold-and-thrust belt. reduces rate 56 area. Coupling variations both along-strike along-dip described. find segmented least two highly locked segments narrow areas weak coupling. segmentation consistent with our knowledge historical ruptures instrumental seismicity region. Intersegment zones (Iquique, Mejillones) correlate high background local tectonic complexities or downgoing plates. The rupture either Paranal Loa segment alone could easily produce Mw 8.0–8.3 rupture, we propose (from 22.5◦S 20.8◦S) may one ruptured 1877.