Terrestrial reference frame SC20 for monitoring crustal deformation in the adjacent areas of the South China block

Abstract

SUMMARY For the application of crustal deformation monitoring, users in East Asia need to have a terrestrial reference frame (TRF) that is consistent with the latest International Terrestrial Reference Frame 2014 (ITRF2014). We selected 12 core stations having 10 yr of continuous GPS observation (2010–2020) by the enhanced criteria and established a stable South China Reference Frame 2020 (SC20). The SC20 is defined as having no-net rotation within the stable South China block and an angular velocity from IGS14 to SC20 in Cartesian coordinates of (−0.1736 ± 0.0088, −0.4901 ± 0.0195, 1.0258 ± 0.0114) milliarcsecond yr−1 is obtained. The root-mean-square velocities of the core stations are 0.23 mm yr−1 in the north, 0.22 mm yr−1 in the east, and 0.30 mm yr−1 vertical and the SC20 frame can be confidently used within 8 yr beyond its useful life (2010–2020) without causing any deviation in position. Finally, the three-component velocities of 194 stations with respect to SC20 are obtained in East Asia. The deformation result can fully highlight the relative deformation of the boundary zone of the active block, which is beneficial to the crustal determination related to the location of strong earthquakes. The SC20 also degrades over time just as with ITRF, so we will be regularly updating it every few years by adding more reference stations and longer periods of observations and in time after major geophysical events.