169 tangible tremors follow Tuesday's quake in Kumamoto

The aftershocks included three measuring up to lower 5, the fifth-highest level on the 10-point Japanese seismic intensity scale, and 11 measuring 4, the sixth-highest level, according to the Japan Meteorological Agency.

The seismically active region stretches roughly 50 kilometers between inland Kumamoto and the Yatsushiro Sea, according to Masashi Kiyomoto, senior coordinator for earthquake and tsunami risk reduction at the agency, at a press conference Tuesday.

Kiyomoto urged caution against continued earthquakes over the next week or so, adding that an earthquake measuring near the maximum intensity of 7 may occur.

Near the epicenter of Tuesday's quake lies the Hinagu fault zone, where strong earthquakes measuring 7 occurred in April 2016.

Kiyomoto said that it is unclear if the latest quake also occurred in the fault zone, but added, "Seismic activity seems to have become active along the fault zone."