Tree Damage and Surface Displacement: the 1931 M 8.0 Fuyun Earthquake

Abstract

Trees often suffer damage during large earthquakes due to shaking and rupturing of the ground surface from associated faults. The damage may result in temporary asymmetric growth and reduction in the width of annual growth rings. Observation of tree displacement and tree ring analysis of the circle shrub Sabina pseudosabina on the Fuyun fault zone in northwest China reveals dextral displacement as much as 10.8 m along the surface rupture located near the epicenter of the 1931 M 8 Fuyun earthquake. Tree ring analysis indicates a sharp change in ring width in 1931. Rings of 1931–1934 are much narrower in width than those formed immediately before 1931 and after 1934. No obvious abnormalities in average temperature or rainfall during 1931–1934 were recorded. The results of ring analysis and the displacement of trees indicate that the sharp change of tree ring width and the maximum displacements of 10–15 m near the epicentral area were generated by surface rupturing in the 1931 M 8.0 Fuyun earthquake.