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松潘一平武地震前后的地壳形变资料表明,在震中周围地形变具有规律性变化.1975年7—9月第一次复测,发现1960年以来岷江断裂两盘存在年速率约3毫米的缓慢相对运动;1975年底再次复测,证明东盘加速上升.当临近震前2—3月时,一些构造敏感点附近出现短期形变异常.与此同时,松潘川主寺短水准亦呈短期异常.震后漳腊盆地相对下沉,较场迭溪弧形构造南侧相对抬升,南坪西侧余震延伸方向上形变则呈弹性恢复,从震源外围反映了地震的孕育释放过程.文中还通过地形变与地震要素的探讨,初步建立了用垂直形变量估算震级的关系式.计算结果符合实际,说明用于中长期预报具有一定意义.
Crustal deformation data before and after the Songpan-Pinghu earthquake show that the deformation around the epicenter has regular changes from July to September 1975. The first retest in July-September 1975 found that there were slow relative velocities of about 3 mm in both plates of the Minjiang fault since 1960 Re-testing again at the end of 1975, proving that the east disk accelerated upward, and short-term deformation anomalies occurred near some structural sensitive points just two to three months before the earthquake, while at the same time, the short leveling of Songpan Chuanzhusi also showed short-term anomalies Afterwards, the Zhangla Basin relatively sinks, which is relatively uplifted to the south of the arc-shaped tectonic setting of the Judianxi and the elastic deformation of the aftershock in the west of Nanping is resiliently restored, reflecting the process of geocentric release from the periphery of the source. With the discussion of seismic elements, the relation between magnitude and vertical deformation is established preliminarily.The calculation results are in line with the reality, which shows that it is of certain significance for mid- and long-term prediction.