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Abstract When slip at shallow depth occurs during large subduction zone thrust events,Pwave energy enters the water layer and establishespwP, the reverberating waves called “water bounces” that followpP. For water depths ≥5–6 km (i.e., near the trench) above the shallow slip,pwPmanifests in a strong ~10‐s period ringing that can persist for minutes into the teleseismicPwave coda at all azimuths. Deeper slip can generate shorter‐periodpwPringing at trenchward azimuths. At large distances,P_codawindows have several‐minute‐long intervals free of secondary arrivals. We consider rmsP_coda/rmsPamplitude ratios at distances from 80° to 120° as a potential proxy for occurrence of shallow slip for 39M_W7.5+ megathrust earthquakes from 1990 to 2016 with estimated slip distributions. Ratios for the 15‐ to 7‐s‐period band have a strong bimodal distribution, with higher averageP_coda/Pamplitudes observed for ruptures with slip extending to shallow depth.