Erta Ale is a remote and rarely visited volcano that is known currently to have an active lava lake in its summit crater. Erta Ale has undergone seven eruption events in the past 125 years.
Re: What are the differences between Signal ground, Chasis ground and Earth?? Signal Ground is a reference point from which that signal is measured, due to the inevitable voltage drops when current flows within a circuit, some 'ground' points will be slightly different to others. There may be several signal grounds in a circuit.
Signal to Noise Ratio. The signal to noise ratio is the difference between the noise floor and the reference level. The reference level is determined by the person making the measurements. For amplifiers, the reference may be, full power, one volt, one watt into a given load or any number of other things.