An earthquake with a magnitude of three-point-seven struck off the coast of Incheon early Monday morning.

According to the Korea Meteorological Administration(KMA), the earthquake was reported at 1:28 a.m. in waters about 25 kilometers west of Ganghwa County in the western city near Seoul.

It was initially presumed to be a magnitude four quake, triggering early earthquake warning systems that included sending an emergency text notification of the event to the mobile phones of those in the Seoul metropolitan area. However, the magnitude was downgraded later after an additional analysis.

The depth of the epicenter was estimated at 19 kilometers.

Although no reports of damage have been made so far, at least 30 calls were made to the anti-disaster authorities in Incheon from those feeling the quake.

It is the first time this year a tremor with a magnitude of three or higher has hit the Korean Peninsula or surrounding sea waters. It was also the strongest quake in the capital area since observations began in 1978. 

The last time a quake stronger than magnitude three-point-five hit the country was around 70 days ago when a four-point-one-magnitude quake occurred in Goesan County in North Chungcheong Province on October 29.