We show how to analyze the locality of memory accesses using Aftermath, an open source tool for interactive, off-line trace visualization and performance analysis of task-parallel programs and run-time systems executing on multi-core and many-core systems. In order to help users detect performance anomalies and pinpoint the exact cause, Aftermath offers adequate visual representations of dynamic events for informal exploration as well statistical tools and filters that provide accurate values for performance indicators. In this paper we give an overview of the capabilities of Aftermath to analyze the locality of memory accesses with respect to NUMA.