Seismic intensity distribution and seismogenic structure analysis of the March 3, 2013 Eryuan Ms5.5 earthquake in Dali, Yunnan Province

By combining the remote sensing interpretation with geological structures and geomorphic features of the study area, the authors have drawn the conclusion that the seismogenic structure of the earthquake resulted from the vertical activity of the main boundary normal fault that happened at the east edge of NNW-trending Liantie basin in the northwest of the Diancang Mountain. Regional structure analysis shows that Liantie basin is a faulted basin developed in Pliocene-Quaternary period along the Tongdian-Weishan faulted zone, suggesting that the present activity of Tongdian-Weishan fracture mainly finds expression in the NEE-trending extension. The main boundary normal fault controls the earthquake length of about 40km and contains at least three SWW-trending imbricated normal faults.