Can be used to detect hidden faults.

It would be known as a seismograph.

In geography, when a seismic waves encounters a certain type of fault, they use seismographs to locate where the fault is hidden.

The correct answer is a seismograph. This device called seismograph can be used to detect hidden faults. It can also record and measure details of earthquakes. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help. 

Answerseafloor spreading;

Answera discharge of static electricity;