Abstract:

In order to discuss present tectonic stress adjustment process before and after Japan MW 9.0 earthquake in North and Northeast China and its research significance, the measurement of present insitu absolute crustal stress state (including magnitude and orientation) and the realtime monitoring of crustal stress values and GPS measuring in North and Northeast China were carried out. The research results show that the adjusting periods of the tensile effect triggered by Japan earthquake coseismic displacement in Shandong peninsula, north region of North China and Northeast China are about 6 months (the adjustment ended about in September 2011), 15 months (the adjustment ended about in June 2012) and 26 months (the adjustment ended about in May 2013), respectively, and that the adjusting cycle of the tensile effect is proportional to the size of coseismic displacement. In this adjustment process, the conversion of the regional tectonic stress action way and tectonic stress field may have happened, which may cause the major geological events (such as earthquakes and so on). The earthquakes, such as MS 4.8 on May 28, 2012, MS 3.2 on May 29, 2012, MS 4.0 on June 18, 2012, MS 3.3 on August 26, 2012, and MS 3.0 on January 11, 2013, in Tangshan and its around region, may be triggered by the conversion in the northern part of North China, and the earthquake swarm in Songyuan city in Jilin Province since October 31, 2013 may be caused by the conversion in Northeast China, rather than small earthquakes before a strong earthquake.

Key words: present insitu absolute crustal stress state measuring and crustal stress value realtime monitoring, GPS measuring, adjustment period of tensile effect, the conversion of the regional tectonic stress action way and tectonic stress field, Songyuan earthquake swarm