Subsurface structure and impact process of Yilan Crater, northeastern China

Yilan Crater is a newly discovered impact structure in Northeast China. However, the impact process and its subsurface properties have not been properly investigated yet. Here we employed multiple seismic methods to gain insight on its subsurface structures, based on an ultra-dense observation with 220 seismic nodes. We observed a clear site amplification within the circular region of the crater generated by loose sediment and impact-fractured rocks. The resulting bowl-shaped structure beneath the Yilan crater was further revealed by the ambient noise tomography and Horizontal-to-Vertical Spectral Ratio analysis. Multiple solutions for the impact velocity and diameter were found by a parametric investigation, while the impact energy is around 1 E17 Joules, likely representing one of the most significant impact events in the last 80,000 years. These findings offer new insights into the Yilan impact event and its potential effects on the surrounding environment, highlighting the need for further multidisciplinary investigations. (Figure presented.)