Co-seismic and post-seismic effects of the Tohoku-Oki MW 9.0 earthquake in North and Northeast China

Using the US Geological Survey (USGS) finite fault model, the co-seismic horizontal displacement and horizontal principal stress field in North and Northeast China generated by the Tohoku-Oki M-W 9.0 earthquake of March 11th, 2011, were retrieved by linear elastic finite element numerical simulation. On this basis, the static Coulomb failure stress variations of the main active faults and tectonic zones in North and Northeast China were calculated, and the triggering effect of the earthquake on seismicity in North and Northeast China was discussed. Results were as follows: (1) the co-seismic horizontal displacement field caused by the great earthquake was eastward in North China; the maximum value, which occurred in the Shandong Peninsula and north Jiangsu Province, was about 12 mm; and the values gradually decreased from east to west. The co-seismic horizontal displacement field in Northeast China was SE-SEE and the maximum value, which occurred in northeast Jilin Province, was about 30 mm. The simulated results for the co-seismic horizontal displacement field were in good agreement with GPS observational results. (2) The near-surface co-seismic maximum horizontal principal stress (Delta sigma Hmax) was tensile stress ranging from 0 to 2.0 KPa. From Northeast China to North China, the direction gradually altered from NW to NWW to nearly EW to NEE. The co-seismic minimum horizontal principal stress (Delta sigma Hmax) was compressive as well as tensile stress, with a magnitude of 0-0.75 KPa, which is approximately equal to zero. From Northeast China to North China, the direction gradually changed to NNW from NE to NNE to nearly NS. Although the co-seismic stress effect generated by the great earthquake had some effect on the present tectonic stress field of North and Northeast China, its influence was too slight to change the present framework of the regional tectonic stress field. (3) Coulomb failure stress variations on active fault zones in North and Northeast China mainly increased; however, the amount of increase was less than 1 KPa. The increases were largest in the middle and northeastern segments of the Tancheng-Lushan fault zone and the Mishan-Dunhua fault zone. The Tohoku-Oki Mw9.0 earthquake did have some triggering effect on seismic activity in North and Northeast China, but the effects were limited.