This paper describes the finite element analysis of an alternative mechanically-stabilized-earth (MSE) wall, subject to dynamic loading using PLAXIS®-2D. The model incorporates Lightweight expanded shale aggregates (LWA) as backfill materials. Dynamic loading includes sinusoidal harmonic motions from 0.2 to 6Hz frequencies. The numerical simulation is used to verify experimental shake-table studies on a small-scale prototype. The model features multiple layers of backfill materials reinforced with synthetic geo-grid sheets and loaded with a shallow foundation. Discussions include the effectiveness of numerical techniques to model various features of the MSE wall. Numerical results are compatible with the shake-table experimental data. Further, simulations indicate the effectiveness of using equivalent springs in the small-scale model to replicate absorbent boundaries in a true-scale MSE wall. Moreover, the numerical output shows the sensitivity of MSE wall response to the frequency of the base excitation. However, the effect of damping is not readily exhibited in analysis. In summary, the results contribute to better understanding of MSE response to seismic events, performance of lightweight backfills, and reliability of numerical solutions, while warranting further analytical work using advanced soil models.