  We prove the equivalence of two holographic computations of the butterfly
velocity in higher-derivative theories with Lagrangian built from arbitrary
contractions of curvature tensors. The butterfly velocity characterizes the
speed at which local perturbations grow in chaotic many-body systems and can be
extracted from the out-of-time-order correlator. This leads to a holographic
computation in which the butterfly velocity is determined from a localized
shockwave on the horizon of a dual black hole. A second holographic computation
uses entanglement wedge reconstruction to define a notion of operator size and
determines the butterfly velocity from certain extremal surfaces. By direct
computation, we show that these two butterfly velocities match precisely in the
aforementioned class of gravitational theories. We also present evidence
showing that this equivalence holds in all gravitational theories. Along the
way, we prove a number of general results on shockwave spacetimes.
