We implement a non-parametric estimation of an Epidemic-Type Aftershock Sequence triggering function with the directionality of the aftershock activity included in the estimation. To accomplish this we modify the triggering function v such that it is instead a function v(s, t, m, θ), depending not only on the magnitude of previous events but also on the relative angular separation between events, relative to the primary fault plane associated with the prior event. These relative angles depend on estimates of the principal fault planes associated with each event. We estimate these fault planes using all seismic activity within 100km2 of a main shock event using M > 2.0 events in the entire earthquake catalog.