ORN and observed seismicity over a 2-month period. The events have been located using the HYP code and a preliminary velocity model (see Table S1 in supporting information). Red dots denote events that have been used for the calculation of the P-wave minimum 1-D model, meanwhile events presented by a black dot were excluded from the calculation for quality reasons. The depth always denotes depth beneath seafloor. All stations have been set to a depth of 0 km, to keep the calculation simple. The histogram in the lower-right corner gives a count of earthquakes per 1 km-interval. The total number of events for the depth interval 0–1 km is 56. Multibeam bathymetry from Ranero et al. (2003).