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The 1931 MW7.8 Fuyun earthquake occurred around the Altai mountains, an intracontinental deformation belt with limited active strain-rate accumulation. To explore whether seismic activity in this deformation belt was affected by stress interaction among different active faults, we calculate the Coulomb failure stress change (ΔCFS) induced by the Fuyun earthquake due to coseismic deformation of the elastic crust and postseismic viscoelastic relaxation of the lower crust and upper mantle. Numerical results show that the total ΔCFS at a 10-km depth produced by the Fuyun earthquake attains approximately 0.015–0.134 bar near the epicenter, and just before the occurrence of the 2003 MW7.2 Chuya earthquake, which distances about 400 km away from the Fuyun earthquake. Among the increased ΔCFS, viscoelastic relaxation from 1931 to 2003 contributes to approximately 0.014–0.131 bar, accounting for >90% of the total ΔCFS. More importantly, we find that for the recorded seismicity in the region with a radius of about 270 km to the Fuyun earthquake from 1970 to 2018, the percentage of earthquakes that fall in positive lobes of ΔCFS resolved on the NNW-SSE Fuyun strike-slip fault, on the NWW-SEE Irtysh strike-slip fault, and on the NW-SE Kurti reverse fault is up to 67.22%–91.36%. Therefore, the predicted ΔCFS suggests that the impact of the 1931 MW7.8 Fuyun earthquake on seismic activity around the Altai mountains is still significant as to hasten occurrence of the 2003 MW7.2 Chuya earthquake at a relatively far distance and to trigger its aftershocks in the near-field even after several decades of the mainshock.

Fast and slow earthquakes are predominantly generated along faults constituting active plate boundaries. Characterized by repeated devastating earthquakes and frequent slow slip events and tremors, the Alaska megathrust presents a chance to understand the complicated dynamics of a subduction system changing from steep to shallow dips associated with enigmatically abundant fast and slow seismic events. Based on three-dimensional thermal modeling, we find that the downgoing metamorphosed oceanic crust containing bound water releases a large amount of fluid and causes the recurrence of fast and slow earthquakes by elevated pore fluid pressure and hydrofracturing. The seismogenic interface and the slow slip events (SSEs) identified beneath the Upper Cook Inlet coincide well with the slab metamorphic dehydration regions. The observed slow earthquakes with quasi-stable fault slips preferentially occur, accompanied by high dehydration and temperature downdip along the transition zone.

The modal analysis of the automobile transmission housing assembly is formulated using 3D graphics software Pro/E together with Finite Element Method in order to reduce the noise and vibration by accurately identifying the noise source of the transmission in the neutral idle condition. Besides, the calculation of meshing frequency of gear pair is conducted. After comparing model analysis results with the calculation results, we can intuitively analysis the dynamic characteristics of the transmission housing assembly and find out sensitive parts of the housing vibration. In order to enhance the structural stiffness of the transmission housing assembly and allow intentionally the natural frequency of the transmission to avoid the gear meshing frequency, we increase the thickness of thin plate or add the strengthening rib on the weak parts of the transmission housing assembly. The results of the above modified modal reanalysis show that low mode frequencies of the transmission housing assembly are greatly improved after optimization, and avoid the gear meshing excitation frequency effectively. The probability of resonance for the transmission housing assembly in use will be greatly reduced, which can well achieve the purpose of enhancing the dynamic characteristics of the transmission housing assembly. [ABSTRACT FROM AUTHOR]