“…The velocity increases at the top of D 00 are primarily detected by reflections and triplications, which arrive ahead of the corereflected PcP and ScS phases (e.g., Avants et al, 2006b;Chaloner et al, 2009;Ding and Helmberger, 1997;Gaherty and Lay, 1992;Houard and Nataf, 1993;Hutko et al, 2008Hutko et al, , 2009Kendall and Nangini, 1996;Kendall and Shearer, 1994;Kito and Krü ger, 2001;Kito et al, 2004Kito et al, , 2007aKohler et al, 1997;Lay and Helmberger, 1983a;Lay et al, 2004aLay et al, , 2006Reasoner and Revenaugh, 1999;Sun and Helmberger, 2008;Sun et al, 2006Sun et al, , 2009Takeuchi and Obara, 2010;Thomas and Weber, 1997;Thomas et al, , 2004aThorne et al, 2007;Weber, 1993;Weber and Davis, 1990;Wright and Lyons, 1975;Wright et al, 1985;Lay, 1987a, 1990). The clearest observations of deep mantle triplications are from distances of 65 to 95 , where the critical angle interaction with the velocity increase greatly enhances the amplitudes of the reflected signals relative to precritical distance ranges.…”