Study Of The Current Tectonic Activities And Crustal Deformation In Northeast China

Earthquakes can cause coseismic displacements in the vicinity of their near-field,and can also cause post-earthquake deformation with time through the transmission of surrounding medium.Since the occurrence of the Great Northeast Earthquake in 2011,the deformation characteristics of Northeast China are necessary.Scientific issues.This paper extracts the velocity field of Northeast China and the Russian Far East after the 2011 MW 9.0 earthquake in Japan and the post-earthquake displacement of Northeast China and the near-field region.The following three scientific questions are completed:(1)This paper get the spatial characteristics of the Northeast China current crustal velocity field after the Japanese MW 9.0 earthquake,and the activity characteristics of the northern part of the Tanlu fault zone in China;(2)Use multi-scale spherical wavelet method to get strain rate field which spatial distribution characteristics are analyzed.The post-earthquake relaxation response characteristics and background deformation field characteristics of each GPS station in the 2011 Mw9.0 earthquake in Northeast Japan are studied.(3)Using the Pollitz viscoelastic sphere dislocation theory,the postearthquake displacement of the near-field and far-field GPS data of the Mw 9.0 earthquake in Northeast Japan in 2011 was used as a constraint,and the calculation of post-earthquake displacement in Northeast China was optimized using the supporting calculation program.The thickness of the lithospheric elastic layer and the mantle viscosity factor in the northeastern region.In terms of velocity field characteristics: if the relaxation effect of the Great Northeast Earthquake in Japan is not deducted,the southeastern body of the Eurasian Plate is a southeastern movement,and between the Yilan-Yitong fault and the Nenjiang fault zone,the crust appears counterclockwise.Rotation,other areas move to the southeast direction,the direction is consistent,and the velocity on the east side of the Dunhua-Mishan fault increases significantly.The Dunhua-Mishan fault and the YilanYitong fault showed obvious extension on both sides,and the difference between the two fractures was obvious.The shearing motion of the two faults was not obvious.In terms of strain characteristics,the surface strain rate shows the NW-SE direction tensile and NE-SW direction extrusion,and the surface strain rate shows the southern end of the Yilan-Yitong fault,the northern end of the Nenjiang fault zone and the southeastern part of the Russian Far East.Pressure state.The maximum shear strain rate is relatively large in the Yilan-Yitong fault,the south side of the Dunhua-Mishan fault and the southeastern part of the Russian Far East.The response of each GPS station to the post-earthquake relaxation of the Mw9.0 earthquake in Northeast Japan in 2011 is generally southeastward,and the relaxation variable decreases with the increase of the epicentral distance.The surface strain rate of the relaxation effect is generally represented by the NW-SE direction and the NE-SW direction.The surface strain rate shows the Yilan-Yitong,the southern end of the Dunhua-Mishan fault,the northern end of the Nenjiang fault zone,and Russia.The Far East has a crushing characteristic,and other areas have a tensile feature.There is an obvious high shear rate high value area at the southern end of the Far East border between China and Russia.After deducting the slack deformation caused by the Mw9.0 earthquake in northeastern Japan,the overall upper strain rate still shows the NW-SE direction tensile and NE-SW direction extrusion,and the maximum surface strain rate is still located in the YilanYitong fault.It is at the southern end of the Dunhua-Mishan fault,the second Songhuajiang fault zone,and the southernmost part of the Russian Far East and China's border.At the southern end of the Yilan-Yitong fault and the Dunhua-Mishan fault,the maximum shear strain rate in the southern end of the Russian and Russian Far East borders still exists,indicating that the strain accumulation in these areas is fast and continues.By simultaneously constraining the far field data of Japan's near-field and northeastern China in the Mw9.0 earthquake in northeastern Japan,and considering the aftershock,the post-earthquake displacement of 2.5-4.5 years is considered to be completely due to the viscous relaxation effect,and finally the use of Pollitz's viscoelastic sphere dislocation theory repeatedly fits the GPS observation data from 2.5-4.5 years after the earthquake,and determines the optimal solution of the viscosity coefficient and the thickness of the lithospheric elastic layer in the far field of the 2011 MW 9.0 earthquake in Japan,respectively,1 ×1018 Pa·s and 35 km.