CO‐SEISMIC GRAVITATIONAL POTENTIAL ENERGY CHANGE AND ITS TECTONIC IMPLICATIONS: A CASE STUDY IN TIBETAN PLATEAU AREA

Earthquakes not only release seismic-wave energy, which decays eventually, but also give rise to permanent deformation in the Earth. This permanent deformation causes gravitational potential energy (GPE) change. Previous researches showed that the GPE change is a good indicator of extensional and compressional tectonics. In this paper, we first proposed an effective method to compute co-seismic GPE change for a SNREI (spherically symmetric Non-rotational Elastic Isotropic) Earth according to the point dislocation theory. This method is applicable to both shear and tensile earthquakes. We then applied this method to compute the contributions from earthquakes occurred over Tibetan plateau area from 1976 to 2013 to the crustal GPE change. The results show that earthquakes occurred in central and western part of Tibetan plateau caused the crustal GPE to decrease while those in eastern part caused it to increase, which correspond to extensional and compressional tectonic status, respectively, in this area. Furthermore, the impact of earthquakes occurred from 1999 to 2013 was larger than that of earthquakes occurred from 1976 to 1998.