ON THE FRACTURE ZONES OF CHANGMA (昌马) EARTHQUAKE OF 1932 AND THEIR CAUSES
SHIH CHEN-LIANG HUAN WEN-LIN YAO KUO-KAN HSIE YUAN-TING
On 1932 December 25, a destructive earthquake of magnitude 7.6 occurred in the region of Changma, Kansu corridor. In the meizoseismal area, there appeared a large number of fissures and fractures, consisting of types of tension, compression and shear. In this paper, the authors analyse the forms and conditions of producing different kinds of fractures associated with the characteristics of regional tectonics, and then, propose a tentative pattern of field stress related to the seismogenesis for the present earthquake.This seismic event was principally due to the nearly north-south horizontal com-pressional force, which had long been dominating this region since the time of Cretaceous. The new seismic fractural zones appeared nearly coincided with the active area of Changma tectonic faulting. Therefore, it may be concluded that the present earthquake was an episode in the long term of Changma faulting movement.