Active tectonics and seismic hazard assessment in Shaanxi, Gansu, and Ningxia Provinces, China

点击翻译按钮获取中文摘要

The provinces of Sha'anxi, Gansu, and Ningxia lie between the southern and western margins ofthe Ordos block and the northeastern Tibetan plateau. The population of the region is about 70million, of whom approximately half live within large cities, which have grown rapidly and recentlyaround the nuclei of much smaller cities that are known to have been destroyed by earthquakesin the historical past. The remainder of the population is rural, and live in highly vulnerable buildings.The region has suffered three of the most deadly earthquakes in recorded history; the 1556 Huaxianearthquake was responsible for the deaths of over 800,000 people, and other historical earthquakesare known to have killed over 100,000 people. This project aims to make a significant improvement in the assessment of seismic hazard in the region,and is particularly timely because the study area covers the most populous part of the Chinese end of the Silk Road Economic Belt, a planned investment of hundreds of billions of dollars that will transform communications, transport and trade across Eurasia.Unlike countries around the Pacific Rim, where earthquakes occur quite frequently, on faults whose locations are well known, China is exposed to hazards from earthquakes that occur on a widelydistributed system of faults, whose locations are poorly known -- or not known at all until an earthquake occurs. The central aspect of this earthquake hazard is that the intervals between successiveearthquakes on the same section of fault are thousands of years. In order to characterize accuratelythe deformation of a region, therefore, we need to determine the distribution, rate, and roleof the active faults across the region over the past 10,000 to 100,000 years.We shall shall achieve this by combining techniques of field geology, geophysics, satellite-based mapping,and measurements of the deformation of the Earth' surface using GPS and satellite radar. We shall combine these observations into a coherent picture of the deformation of the region, which will be usedto make a new map of seismic hazard of the region that is both more accurate and more detailed than existing maps.