Magnitude 5.9 Earthquake Strikes Southern Ibaraki, Injures 37

A magnitude 5.9 earthquake struck southern Ibaraki Prefecture at 2 a.m. on August 23, shaking eastern Japan including Tokyo. The Japan Meteorological Agency recorded a maximum intensity of lower 5 on the Japanese scale in 17 municipalities across Ibaraki, Saitama, Chiba and Tokyo.

At least 37 people were injured in Tokyo and the surrounding prefectures of Ibaraki, Saitama, Chiba and Kanagawa, according to the Fire and Disaster Management Agency. One woman in her 80s in Yokohama sustained a serious back injury after falling from bed. No fatalities were reported.

The epicentre lay at a depth of 68 kilometres. The mechanism was a reverse fault under east-west compression at the boundary between the Pacific and Philippine Sea plates. No tsunami warning was issued.

Long-period ground motion of class 2 was observed in southern Saitama, northwestern Chiba and Tokyo's 23 wards. Railway services faced widespread delays and suspensions the following day.

Prime Minister Sanae Takaichi instructed officials to collect damage information and warned residents in affected areas to remain alert for aftershocks of similar intensity for about a week, especially in the first two to three days.

The agency noted that past cases show a 10 to 20 percent chance of a comparable quake within a week after an event of this size. Strong shaking can loosen slopes and raise the risk of rockfalls.

The event is a reminder of the seismic exposure of the Kanto region, where dense urban infrastructure amplifies the practical consequences of even moderate quakes.