This time-distance plot of earthquakes shows that the Mw=6.2 aftershocks extended for about 10 km. Despite the calculated Coulomb stress increases to the NE and SW shown in the previous image, no remote aftershocks occurred beyond this 10-km-long zone until the Mw=7.1 struck a little over a day later. At that time, not only did the rupture extend another 30 km, but remote aftershocks appeared in the northeast near Oita, beyond the end of the rupture, possibly on the stressed Beppu-Haneyama Fault zone. You can also see those in the aftershock map. The disk size is proportional to earthquake magnitude. Modified and interpreted from a JMA release on April 20.