It will almost certainly take several tens of thousands of years, if the growth rate for L'ihi is comparable to that of other Hawaiian volcanoes (about 0.1 foot per year averaged over geologic time).
A: The Richter scale is used to quantitatively measure the magnitude of an earthquake. This tool was devised by the seismologist Charles F. Richter in 1935. Full Answer >
A variation of this is used  in Europe and is known as the Macroseismic scale.    Earthquakes are measured with a seismometer.   Seismometers and accelerometers are used to measure the  acceleration of the ground surface and the total amplitude of  seismic waves during an earthquake.