**2. Study Area Description**

The Yellow River Estuary is located in the north of Shandong Peninsula, China (118.73◦ E–119.65◦ E, 38.1◦ N–38.3◦ N) (Figure 1). In this sea region, the water depth ranges from 0 to 18 m. When the water depth is less than 15 m, the predominant sediment type is silt combined with a minor quantity of silty sand; when the water depth is greater than 15 m, the predominant sediment type is silty clay. The wave height increases gradually with the increase in water depth and reaches the maximum value near the water depth of 10 m. As a consequence, wave forces on the seabed increase first, and then decrease with the increase in water depth. The seabed gradient ranges from 1/2000 to 1/500. Waveinduced liquefaction, which can cause seabed sediment to lose stability and slide, is the main geological disaster in the sea area.

There are two main factors for the selection of the Yellow River Estuary as the study area. First, the detailed geological data of the study area, such as water depth, sediment types, waves, currents, and so on, have been collected by the First Institute of Oceanography, MNR, and can be used in this study. It is of vital importance to obtain detailed geological environment data, as the acquisition of data about submarine landslides is very difficult and incomplete. Second, there are a great many submarine landslides and human activities located in this sea area, which means this study has research significance and practical engineering safety-guidance significance. There are a lot of micro-submarine landslides that have been discovered since the 1990s in the study area. The results of the field geophysical investigation [19] show that the form factor of the submerged delta landslide zone in the Yellow River Estuary is mainly hydrodynamically triggered by submarine liquefaction. Furthermore, the SINOPEC Shengli Oilfield is in this sea area, and as a consequence, hundreds of submarine oil platforms and submarine cables are located in this area.

**Figure 1.** Location map of the study area.
