•To present a resilient four-level framework for the centralized cost-effective multistage DNRP considering decentralized double-layer multistage MGRP.•To model different peak ground accelerations of moderate-to-strong earthquakes based on critical seismic parameters.•To provide a non-convex mixed-integer nonlinear formulation for jointly allocating substations, feeders, renewable DERs and ESSs.•To assess seismic vulnerability of substations, feeders and DERs according to their respective fragility curves. In this paper, a new resilient framework is presented for distribution network reinforcement planning (DNRP) with the consideration of renewable-based multi-microgrids (RMGs) to mitigate seismic risks. For this aim, the proposed framework is formulated as a non-convex mixed-integer nonlinear four-level optimization problem. The first level outlines a short-term corrective measures problem to remedy seismic risks using feeder reconfiguration and distributed energy resources rescheduling. The second level represents an earthquake-related catastrophic failures problem in which peak ground acceleration and distribution component vulnerability are modeled through attenuation functions and fragility curves, respectively. The third and fourth levels, however, describe coordination of a decentralized double-layer multistage microgrid reinforcement planning (MGRP) problem and a centralized cost-effective multistage DNRP problem to characterize seismic-resilient optimal reinforcement plans. Due to its desirable handling of multi-level optimization problems having a non-convex mixed-integer nonlinear nature, the multi-computational-step, multi-dimensional, multiple-homogeneous improved melody search algorithm, referred to as a symphony orchestra search algorithm (SOSA), is used to solve the proposed framework. The performance of the newly developed framework is numerically analyzed through implementing it to the standard 33-, 54-, 119- and 136-node distribution test networks. The numerical results well corroborate the sufficiency and profitableness of the proposed framework in achieving low vulnerability and high resilience to seismic risks.