A series of earthquakes have been observed off the eastern coast of Chiba Prefecture, near Tokyo, since Tuesday. Japanese officials are urging people in the region to be on the alert for further seismic activity.

Japan Meteorological Agency officials say a magnitude 5.2 earthquake struck the area at around 5:43 a.m. on Friday. It was the strongest jolt in the series of earthquakes centered off the eastern coast of Chiba.

A tremor with an intensity of 4 on the Japanese scale of 0 to 7 was registered in a district in Saitama Prefecture, north of Tokyo, and in some parts of Chiba Prefecture.

A total of 16 quakes with an intensify of 1 or stronger were observed around the epicenter by 11 a.m. on Friday.

Agency officials say that in the same area in the past, high levels of seismic activity continued for one week to several months following an earthquake of around magnitude 5.

The officials say this phenomenon was observed in the area every three to six years between 1996 and 2018.

Hirata Naoshi, a Professor Emeritus at the University of Tokyo, says he does not think the recent series of tremors will immediately lead to a major earthquake.

But he noted that the probability of a quake of around magnitude 7 striking the southern part of the Kanto region, which includes Tokyo, within 30 years is 70 percent. He says this means an earthquake of that scale could hit the region at anytime.

Hirata says a magnitude 7 quake could cause high tsunami waves.

He advises people to prepare for a major earthquake by securing furniture, making their houses quake-resistant, and checking evacuation routes.