关键词: 断层崖, 演化, 古地震

Abstract: This paper deals with the degradation of fault scarp and the identification of paleo-earthquake in the light of theoretical and mathematical analysis of scarp development processes. We propose some models for fault scarp degradation in unstable and diffusion stages, and give out their mathematical solutions. From these solutions, the quantitative relation between geometrical features and/or sedimentary structures of fault scarp is analyzed. Furthermore, the precise expressions of the isochronous form-line of the scarp profile, the maximum gradient of scarp, and the sectional area of scarp deposits are established quantitatively for the use of paleo-earthquake research. Based on the field investigation, as well as experimental and mathematical analysis, the comprehensive indicators for identifying paleo-earthquakes associated with fault scarp, including geometrical, sedimentary, structural and experimental features, are summarized. Case studies on the fault scarp of the eastern Helanshan Fault at Hongguozi and fault scarp of the F 201 Fault at Mengjiawan were carried out. The results of these two studies reveal 2 series of 4 paleo-earthquake events that had occurred on the two faults respectively. The characteristics and recurrence intervals of these events have been studied in details. It is determined that the recurrence interval of paleo-earthquke events on the eastern Helashan Fault is 2.2～2.6ka, and that on the F 201 Fault is 3.3～4.0ka.

Key words: fault scarp, degradation, paleoearthquake