In April 2016, an earthquake with a magnitude of 7.8, the strongest in 70 years, struck Ecuador, causing material damage amounting to millions of dollars and several hundred casualties. This earthquake is linked to the sudden rupture, at a depth of more than 20 km, of the subduction fault over a 100 km by 30 km area.

An international intervention (Ecuador, France, United States, United Kingdom) immediately after the earthquake made it possible to rapidly deploy a network of about 100 seismometers on land and at sea and to highlight complex slip behaviours in this part of  the Ecuadorian subduction zone with aseismic slip, so-called afterslip some of which occurred unexpectedly in areas characterized by slow earthquakes during the interseismic period (the decades preceding the major earthquake). These phenomena, which are still poorly understood and play a role in the seismic cycle, affect the subduction fault in Ecuador at depths that can be reached by current methods of marine geophysics investigation.

Through the HIPER campaign, we want to understand the relationships between 3D structure, fluids and spatio-temporal variations of seismic and aseismic slip modes. To do so, we need to acquire high-resolution geophysical data for:

• image the roughness of the interplate which can play the role of asperities, up to the rupture zone of the 2016 Pedernales earthquake;
• image the degree of fracturation of the upper and downgoing plates, the subduction channel and buried sediments;
• image region of fluids along the interplate, in the downgoing and the upper plates;
• obtain structure variations and physical parameters in 3D;
• locate seismicity, transient signals and slow earthquakes in relation to the structures we will image.