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 >
This is because we can't easily measure the energy the way we can with an electric circuit, so seismologists commonly use a relative measure. It is easier to choose a particular earthquake recorded at a particular distance as a standard earthquake, call it a magnitude 1. An earthquake that causes ground motion at a seismic station (when corrected for distance) 10 times larger than the reference earthquake is M2. An earthquake causing motion at that distance 10 times larger than an M2 is an M3, and so on.