There had been 67 M≥3.5 events till Dec. 1997. The nodal plane II of the focal mechanism solution is the main rupture plane of the earthquake, which strikes NWW, P axis azimuth N57°E, elevation 10°, showing left lateral strike slip rupture.
The focal-mechanism solution of Qingdao earthquake sequence is calculated by using the digital data and first motion,and consistency index Z is analyzed,and got the stress field characteristics in earthquake development and the regularity of the earthquake preparation and evolution.
Focal mechanism solution obtained from the moment tensors are consistent with the idea that the Indian plate collides northwards with the Eurasian plate and that an eastward spreading exists in the crust of the Tibetan Plateau.
The present-time strain field derived from crustal deformation is consistent with seismic stress field derived from the focal mechanism solutions and the tectonic stress field derived from geology data.
Compared with the average stress field of the region obtained from focal mechanism solutions, the following characteristics of modern tectonic stress field in this region are obtained.
We are going to present the focal-mechanism solution of Fruili earthquake occurred on May 6, 1976, as it results from the analysis, on original seismograms, of the polarities of initial longitudinal waves obtained in 92 seismic stations.
A composite focal-mechanism solution of local AE events, covering a wide solid angle of the focal hemisphere, indicates that shear fractures emit AE waves.