An integrated analysis of source parameters, seismogenic structure, and seismic hazards related to the 2014 MS 6.3 Kangding earthquake, China

Abstract

On 22 November, 2014, an MS 6.3 earthquake occurred in Kangding County, China. Focal mechanism solution shows that the two nodal planes were 235°/82°/−173° and 144°/83°/−8° and the focal depth was 9km. Seismic slip of the Kangding earthquake was bilateral with about 0.5m maximum slip. The rupture zone was confined to depths ranging from 5 to 15km and laterally extended along the slip and strike directions by about 10 and 12km, respectively. Most of the seismic moment was released in the first 5s of the rupture, resulting in an earthquake magnitude of MW 6.01. In contrast, a slip model obtained by interferometric synthetic aperture radar (InSAR) data indicates that the rupture zone was longer than that determined from the seismic data and the earthquake magnitude should be about MW 6.2. Although accounting for the contribution of the MS 5.8 aftershock and the other small aftershocks that occurred during the InSAR observations period, the total moment estimated based on the seismic slip model was significantly smaller than that obtained from the InSAR data. Based on our analysis, we found that the inconsistency between the results determined from the seismic data and the InSAR data may be caused by the decrease in the shear modulus at shallow depths, the noise in the InSAR data, and the occurrence of some afterslips in the northwest region of the fault zone. The seismic slip of this earthquake was too small to release the accumulated energy within the entire Xianshuihe fault. We also found that the Coulomb stress in the northwest zone of the Kangding–Daofu seismic gap increased as a result of the historical, 2008 MS 8.0 Wenchuan and the 2014 MS 6.3 Kangding earthquakes, suggesting that this area is expected to be a high seismic hazard region for the future.