Even with such long arms, the strongest gravitational waves will only change the distance between the ends of the arms by at most roughly 10 m. LIGO should be able to detect gravitational waves as small as h ~ 5 × 10. Upgrades to LIGO and Virgo should increase the sensitivity still further. Another highly sensitive interferometer, KAGRA, which is located in the Kamioka Observatory in Japan, is in operation since February 2020. A key point is that a tenfold increase in sensitivity (radius of 'reach') increases the volume of space accessible to the instrument by one thousand times. This increases the rate at which detectable signals might be seen from one per tens of years of observation, to tens per year.