Strong strain and pore pressure changes are observed after three Mw 4.5+ local and one Mw 7.2 regional earthquakes during 2010‒2017 in borehole strainmeters near Anza, California. The strain change emerges immediately after the earthquakes and lasts 40‒100 days with amplitudes up to 1e−7, larger than the coseismic strain offsets. The pore pressure exhibits change immediately after the earthquakes at some boreholes and with a delay of 4‒10 days at the others. A joint analysis of the observed postseismic strain and pore pressure change suggests that the postseismic strains could be explained by combined effects of poroelastic deformation due to earthquake-induced pore pressure change and elastic deformation due to an earthquake-triggered aseismic slip on a nearby fault. Our study indicates that, in addition to possible aseismic fault slips triggered by an earthquake, pore pressure changes after the earthquake could be even more important in producing postseismic deformation.