Coseismic Deformation of the Ms 6.2 Jishishan Earthquake in Gansu Province Based on High-Frequency GNSS Observation

Objectives The aim of this study is to obtain a high-precision coseismic deformation field of an Ms 6.2 magnitude earthquake occurred in Jishishan County, Gansu Province, China from high⁃frequency global navigation satellite system (GNSS) observation data, which will enable the real-time monitoring of deformations for earthquakes with a magnitude of 6 or higher using a massive network of continuously ope⁃rating reference stations (CORS).

Methods This study employed the PRIDE 3.0 software developed by Wuhan University for high-precision dynamic processing of 32 CORS with high- frequency data, obtaining coseismic deformation time series for each station. For stations showing significant coseismic responses in close proximity, dynamic solutions with large changes at the seismic moment were first excluded. The smoothed single-epoch results before and after the earthquake were retained. For stations with less obvious coseismic responses, the complete ensemble empirical mode decomposition with adaptive noise （CEEMDAN） method was used to detect high-frequency coseismic signals.

Results The main range of permanent deformation caused by earthquake is in the area 30 km away from the epicenter. Stations 5 km away from the epicenter recorded permanent deformation in the east-west direction of 13 mm, north-south direction of 10 mm, and vertical deformation of 8 mm. Modal decomposition identified 13 stations with seismic responses in the east or north directions, including CORS LXJS, GUTI, LXYJ within a 40 km radius from the epicenter. It could detect the seismic deformation far from 100 km better than the original GNSS results, which means this method could be used for waveform signal reconstruction, noise removal, and expanding the distance of CORS monitoring for coseismic signals.

Conclusions This study indicate that various types of CORS equipment with different foundation can monitor earthquake signals. The CEEMDAN method for signal decomposition can detect coseismic signals faraway, providing feasibility for monitoring seismic coseismic deformation information using a large number of CORS resources in the future.