Study of Visoelastic Rheological Model for Posteismic Relaxation:A Case Study on 1997 Mw7.6 Manyi Earthquake

To quantitatively assess the differences born from rheological models on postseismic displacements and viscoelastic Coulomb stress changes,for 1997 Manyi earthquake after decay time from 1 year to 100 years when employing three linear rheological models,namely,Maxwellian model,standard linearsolid model,and Burges model.The results show that:① During transient phase,from 1 to 5 years after Manyi event,standard linearsolid model and Burges model are nearly the same as the other two ones.While during the later phase,starting from 10 years later,Maxwell element does and so are those with Maxwellian model and Burges one.② Similar is their influence on spatial pattern of viscoelastic Coulomb stress changes,though stress shadows and stress-triggering zones enlarge with time.Such tempo-spatial patterns of postseismic displacement field and viscoelastic Coulomb stress changes are consistent with the point that Burges rheological model is general compared with the other two.The uniqueness of rheological model should be figured out by a case-to-case study involving some kind of recursive determination of rhological model through multiple data sources such as GPS,InSAR,levelling,and those measured at different time-intervals so as to explain kinemics of displacement because of postseismic relaxation.