“…In general, the deepest microearthquakes (with reference to the seafloor) are known to occur in the crust/shallow mantle at fast‐/slow‐spreading ridges: for example, 1.8 km at 9°50′N on the fast‐spreading East Pacific Rise (EPR; Bohnenstiehl et al, ; Tolstoy et al, ), 4 km at 35°N on the slow‐spreading Mid‐Atlantic Ridge (MAR; Barclay et al, ), 6 km at 14°45′N on the MAR (Grevemeyer et al, ), 7–8 km at 26°N and 5°S on the MAR (deMartin et al, ; Kong et al, ; Tilmann et al, ; Toomey et al, ), and 10 km at 13°20′N on the MAR (Parnell‐Turner et al, ). By contrast, microseismicity at ultraslow‐spreading ridges tends to feature deep hypocenters: for example, 14 km at the Lena Trough (Läderach et al, ), 15 km at the Segment 8 volcano of the SWIR (Schmid et al, ), 20 km beneath the Knipovich Ridge (Schlindwein et al, ), and 31 km at the orthogonal supersegment of the SWIR (Schmid & Schlindwein, ). From our results in Figures and , the maximum focal depth is ~20 km below the seafloor (bsf) or equivalently 16 km below the Moho discontinuity.…”