They are using thumper trucks and doing a seismic survey to map underground layers and structures.

The main character is Nagate Tanikaze, who lived in the underground layer of Sidonia since birth.

It also gathers planet-wide information about underground layers of ice, rock and possibly liquid water that might be accessible from the surface.

A natural underground layer, often of sand or gravel, that contains water.

An aquifer is an underground layer where the material contains water.

The roundness could be the result of an underground layer of ice that offsets the force of spinning.

They are caused by the compression or stretching of underground layers.

There was a thin, underground layer of moisture from the rain.

An artesian aquifer is an underground layer which holds groundwater under pressure.

On the northern part of the district there exists underground layer of pebbles.