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Monitoring the earthquake cycle in the northern andes from the ecuadorian cGPS network

Abstract:

The continuous Global Positioning System (cGPS) network operating in the northern Andes (Ecuador and Colombia) for about a decade has the main objectives of quantifying interseismic coupling along the subduction interface, detecting occurrence of transient aseismic episodic slip, detailing the rupture kinematics of large earthquakes, recording long-term movements along crustal faults, as well as recording swelling or deflation on the flanks of volcanoes. An opportunity to test the network's timely registry of surface coseismic offsets was provided by the 16 April 2016 Mw 7.8 Pedernales, Ecuador, earthquake whose epicenter was along the western margin of central Ecuador, South America. This large earthquake was the biggest to occur in the northern Andes since 1979 and produced static surface offsets that were recorded by the cGPS stations operating at distances out to ∼400 km from source. Near-field stations, operating along the Ecuadorian littoral recorded static horizontal surface displacements up to 80 cm and high-rate GPS (HRGPS) stations recorded dynamic peak-to-peak displacements reaching 2 m. These measurements, together with seismic data, revealed the southward propagation of the seismic rupture, its spatial extent, and the successive breaking of two main asperities (Nocquet et al., 2017). Here, we provide the complete data set of static coseismic displacements recorded from Ecuador to southern Colombia out to 400 km from the rupture. North of the Pedernales earthquake's foci, in the adjoining Esmeraldas-Nariño segment, some patches show high interseismic coupling and rapid strain accumulation is ongoing. In the 200-km-long Esmeraldas-Nariño segment, the seismic potential is particularly high. cGPS data suggest that the Esmeraldas-Nariño segment is likely a zone of future rupture. a table with information on the 74 continuous GPS (cGPS) stations used in this study, and a figure showing the spatial distribution of slip and time evolution of the 2016 Pedernales earthquake and asperities.