Ann: Gravity survey underway at Canobie, page-8

"Gravity surveys are geophysical techniques used to measure the variations in the Earth’s gravitational field at different locations. These surveys involve the measurement of the gravitational acceleration at the Earth’s surface, typically expressed in terms of milligals (mGal) or microgals (μGal). The purpose of gravity surveys is to map and understand the distribution of subsurface density variations, which can provide valuable information about the geological structure and composition of the Earth’s interior".

"Gravity surveys are based on the fundamental principle that variations in subsurface density cause corresponding variations in the local gravitational field. High-density materials, such as rocks and minerals, exert a stronger gravitational pull than low-density materials like water or air. By measuring these gravitational variations, scientists can infer the distribution of different rock types and geological structures beneath the Earth’s surface".

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