Gale
Wind with a speed between 34 and 40 knots (Beaufort scale wind force 8). (M)

Global Observing System (GOS)
The co-ordinated system of methods, techniques and facilities for making observations on a world-wide scale within the framework of the World Weather Watch. (M)

Ground motion
Seismic vibration of the ground at a particular point, recorded by accelerograph or seismograph in order to determine the vibrational characteristics of an earthquake or explosion.

Groundwater level :
The level at which soil and porous rock begins to be saturated with water. Usually measured as a depth below the ground surface or as a depth above a defined level, such as a shear surface.

Gust
Sudden, brief increase of the wind speed over its mean value. (M)

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