Answer:
False.
Step-by-step explanation:
It's the magnetometer not the GPR that is used for the measurement of the strength of the magnetic field. Magnetometer helps the archaeologists in finding the locations of ferrous based objects or materials.
On the other hand GPR (ground penetrating radar) provides the high resolution depth information of the surveying sites by using electromagnetic radiations. It creates the underground image by using the high pulses. It detect both the conducting and non conducting nature materials.
So it is not right to say that GPR is used to find out the magnetic strength.