Subsidence

Late at night, a pair of enthusiastic lovers came to swim in a small lake in the park, but were unexpectedly swept away by a sudden whirlpool. Three years later, the School of Geology of the University of Natural Science organized an expedition to a huge pothole that suddenly appeared in an open space on the edge of the city. Nina participated in the expedition. Three years ago, Nina was a staff member of the Fastner Mine, the largest mine in the city. Nina's father Hess and brother Dick also worked in this mine. However, a mining accident three years ago completely changed the life of Nina's family. Her father narrowly escaped death after being trapped for 12 days, but witnessed Dick's death. From then on, the family stayed away from the mine and said goodbye to their original life. But the discovery of the huge pothole gave Nina a bad premonition. Sure enough, through a series of high-tech detection methods, Nina obtained a set of astonishing data. This pothole was just the tip of the iceberg, and a larger collapse was imminent. It turns out that after the mining disaster occurred three years ago, the owner of the mine, Montan Energy Company, claimed that it had spent 28 million euros to fill the mine pit in accordance with regulations and that there would be no collapse problem. But the data in Nina's hands is undoubtedly the best proof - Montan Energy Company only made superficial remarks, and the mines deep in the ground did not