Estimation of seismic hazard around the Ordos Block of China based on spatial and temporal variations of b-values

Abstract

Ruinous earthquakes have frequently occurred on the border of the Ordos Block, historically. Thus, where is a future disastrous earthquake around the Ordos? This problem is becoming more and more urgent both in the scientific community and the public, particularly after the 2008 Wenchuan earthquake (Ms=8.0). To this end, we at first compute b-values in and around the Ordos Block based on the updated catalogue with earthquakes (M≥0.0) from 1 January 2010 to 31 December 2020, and presented the spatial distribution of b-values. By examining the distribution feature of b-values, we chose 14 locations on the border of the Ordos Block where the b-value is relatively low and neo-tectonic faults are active. After that, we calculate the temporal variations of b-values in these 14 places, respectively. Comparing the 14 curves of b-variations with seismic precursors on b-values, we found that four of fourteen b-variations have characteristics of earthquake precursors. Therefore, these four places, located in the western end of the Weihe Graben, both the eastern and western ends of Hetao Graben, and the northeastern front of the Tibet, are considered to be seismically dangerous in the future. Naturally, the seismic damage in these areas is more serious than other places. Hence, the study is helpful in earthquake prediction and also can provide important clues for earthquake hazard assessment around the Ordos Block.