In addition to the existence of the silt deposit, it covers everything presumed to have been on the floor surface at the time of abandonment.

Over the centuries sand and silt deposits made the port unnavigable.

Researchers have estimated that beneficial silt deposits in the valley began about 10,000 years ago.

The situation was aggravated by the reduction in capacity of many of the existing dams due to heavy silt deposits.

In the case of earthquakes, the shaking force can increase the pressure of shallow groundwater, liquefying sand and silt deposits.