Significance of prehistoric liquefaction features in the Xilinhot district, Inner Mongolia, Northern China

摘要

Paleo-ground ruptures, fissures, liquefaction and geomorphic features in the Xilinhot district, Inner Mongolia, northern China, are documented and seismic intensity for the meizoseismal areas and magnitudes of paleoearthquakes are estimated. Trenching investigations revealed a huge paleoseismic ground rupture and fissure zone with a width of more than 200 m. Field investigations and interpretation of remote sensing images demonstrate that active faults related to paleoearthquakes appear to be about 200 km long. Geologic and geomorphic evidences indicate that one large earthquake with a magnitude of about 7.5 at about 13 ka BP or multiple paleoseismic events of M ≥ 6.0 have occurred in the studied area since 53 ka BP. One of the paleo-meizoseismal areas is determined to be near Xilinhot. Seismic intensity in Modified Mercalli scale (MM) is estimated to be larger than VI in the vicinity of the study area and at least VIII in the epicentral region. This is consistent with seismic activities in and around the Xilinhot district in recent years, but higher than anything yet reported. The results provide important data for design engineering and regional planning in order to resist damage from potentially large earthquakes in the future.