Local and Regional Seismic Characteristics of Chemical Explosions in Eastern Margin of the Junggar Basin, Northwest China

Date: 4/24/2019

Time: 05:00 PM

Room: Cascade I

Between September 6 and October 10, 2018, 13 chemical explosions for seismic deep sounding purpose were detonated in the eastern margin of Junggar basin, Northwest China. The source parameters of these explosions, e.g., their locations, depth of charges, property and yield of explosive, were known. They provided immediate constraints for seismic source characteristics, as well as for local and regional seismic wave propagations. In typical cases, three tons of specially designed ammonium nitrate explosive with about 30% trinitrotoluene (TNT) was detonated to generate seismic waves. We roughly assume that 1ton ammonium nitrate explosive equals to 0.5 ton of TNT. According to the result from Non-Proliferation Experiment, the chemical explosions are more efficient at generating seismic signals by a factor of approximately 2 compared to nuclear explosions. Therefore, the explosion effects are equal in TNT equivalent between both chemical and nuclear explosions. Within local and regional distances, these explosions generated abundant broadband digital seismograms, which were used to investigate event attributes, including the discrimination, yield estimation, and epicenter relocations. The spectral ratios Pg/Lg, Pn/Lg, and Pn/Sn were calculated for all 13 explosions and 5 nearby nature earthquakes. The explosion and earthquake sources showed apparently different features in their spectral ratios. Stacked spectral ratios provided a robust discriminant between explosions and natural earthquakes above 2.0 Hz. We calculated body-wave and Rayleigh wave magnitudes for explosions and natural earthquakes, and determined the relationship between mb(Lg) and explosive yield. Relation obtained in this region is consistent to those obtained in East Kazakhstan. This research was supported by the National Key Research and Development Program of China (2017YFC0601206) and the National Natural Science Foundation of China (grants 41630210, 41674060).

Presenting Author: Lian-Feng Zhao

Authors