事故发生在河谷区和丘陵区的交界处，黄土覆盖的丘陵区在北侧，河谷地的二级

The accident occurred at the junction of the valley area and the hilly area. The loess-covered hilly area is on the north side, and the secondary and tertiary basement terraces of the valley are on the south side. The upper soil layer is loess layer and red mudstone with metamorphic gravel

The accident occurred at the junction of the valley and the hilly area, with the loess-covered hilly area on the north side and the secondary and third-level substrates in the valley on the south side. The upper layer of soil is the loess layer and the red mud rock sandwich gravel.

The accident occurred at the junction of the valley and the hilly area, the Loess covered hilly area was in the north, and the second and third basement terraces of the valley were in the south. The upper layer is loess layer and red mudstone mixed with metamorphic gravel