The Influence of the Coulomb Failure Stress Following the 1976 Tangshan Earthquakes on Earthquakes in Tangshan and Its Adjacent Area

The Coulomb failure stress of the Tangshan M7.8 earthquake, Luanxian M7.1 earthquake and Ninghe M6.9 earthquake in 1976 was calculated and the evolution process of the coulomb failure stress of the three earthquakes in Tangshan area is obtained. Based on the comparison between the coulomb rupture stress distribution and the double-difference relocation results of earthquakes with magnitude 1.0 and above since 1979 in the study area (39.0° ~ 40.5°N, 117.0° ~ 119.0°E), it is concluded that the modulation effect of historical large earthquakes on the current earthquakes is weakened. It is possible that from the year 2002 to the year 2020 the areas nearby the Jiyunhe fault were affected obviously, however the areas nearby the Tangshan fault were affected inconspicuous. The Guye M5.1 earthquake on July 12, 2020 and the Luanzhou M4.3 earthquake on April 16, 2021 were inhibited by it.