The　pop-in　events　and　the　deformation　mechanisms　of　(111)　Si　under　spherical　nanoindentation　were　investigated　using　molecular　dynamics　simulations.　The　simulations　result　successfully　reproduced　the　plastic　deformation　mediated　by　high-pressure　phase　transformations　and　dislocation　burst,　and　the　highly　desirable　brittle　fracture　of　silicon.　Quadruple　occurrences　of　the　pop-ins　were　observed　in　loading　curves.　The　one-to-one　relationship　between　the　multiple　pop-ins　and　the　deformation　mechanisms　was　established.　Two　fundamental　processes,　the　asynchronous　occurrences　of　high-pressure　phase　transformation　and　extrusion　of　alpha-Si,　were　identified　from　several　deformation　modes　to　be　responsible　for　the　multiple　pop-ins.　Moreover,　the　dislocation　burst　also　contributes　to　the　plastic　deformation,　and　the　cracks　were　observed　to　contribute　to　the　brittle　deformation,　but　contribute　nothing　to　the　pop-ins.　(C)　2017　Elsevier　B.V.　All　rights　reserved.