COMPARISON BETWEEN THE ACTIVE FAULTS IN THE NEW MADRID SEISMIC ZONE OF THE CENTRAL UNITED STATES AND GANSU PROVINCE IN NORTHWESTERN CHINA

WANG, Z., Kentucky Geological Survey, University of Kentucky, Lexington, Kentucky 40506, WOOLERY, E.W., Department of Geological Sciences, University of Kentucky, Lexington, Kentucky 40506, YUAN, D and WANG, L., Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou, Gansu 730000, China, zmwang@uky.edu, wooley@uky.edu.

Infrequent moderate to large earthquakes are the main source of seismic hazards for both the New Madrid Seismic Zone of the central United States and Gansu Province in northwestern China. In the New Madrid Seismic Zone, there are three active fault segments: the southwest strike-slip segment, the central thrust segment, and the northwest strike-slip segment. In Gansu Province, there are many active fault segments along the Qilian Mountains, including the Haiyuan strike-slip and the Gulan thrust faults, which produced the Haiyuan M8.5 earthquake in 1920 and Gulan M8.0 earthquake in 1927, respectively. Although regional deformation is minimal in the central United States, paleoseismic records suggest that large earthquakes occur about every 500 years on average. In Gansu Province, regional deformation is about 3 to 4 mm per year. The historical and paleoseismic records indicate that large earthquakes occur about every 2,000 to 4,000 years on average. Also, post-event observations show that there is almost no deformation across the Haiyuan and Gulan Faults. Although the New Madrid Seismic Zone and Gansu Province are located in different tectonic environments (stable mid-continent for the New Madrid Seismic Zone and northeastern margin of the Qinghai-Tibet Plateau for Gansu Province), comparing between the active faults and their characteristics in both regions would help us to better understand basic physics of earthquakes in the New Madrid Seismic Zone.