3.7 quake jolts people awake and some fear attack by North

Displays at the Korea Meteorological Administration show data about the earthquake that struck Gangwha County in Incheon early Monday. [NEWS1]

A 3.7-magnitude earthquake that struck Ganghwa County in Incheon early Monday jolted people awake as far as Gyeonggi and Seoul, and was the second exceeding 3.5 magnitude to hit Korea within three months.

The quake struck 25 kilometers (15 miles) west of Ganghwa at a depth of 19 kilometers at 1:28 a.m., according to the Korea Meteorological Administration.

No injuries or casualties were reported.

“I woke up after my balcony's windows were shaking so much,” said a 42-year-old resident of Ganghwa County, which encompasses Ganghwa Island, the fourth largest in Korea, and minor islands such as Seokmo.

“My whole family awoke and the first thing that came to my mind was that North Korea may have fired something.”

According to the meteorological agency, emergency disaster warning texts were sent out to the public in Seoul, Gyeonggi and Incheon 15 seconds after the quake.

“I thought a war was happening after hearing the siren-like alerts from the emergency disaster warning text,” an online post read.

Some people in Seoul said they received the text first and then felt the quake.

“I was startled to hear the siren-like alert [for the warning] and my sofa shook soon after,” a person wrote online.

A resident of Dongjak District, southern Seoul, recalled how disorienting it was to receive the text in the middle of the night.

“After the emergency text was sent, we thought there was a war and my entire family was in complete chaos,” the resident told the JoongAng Ilbo on Monday.

Local fire departments received over 100 enquiries about the earthquake over the night.

Concerns about a possible attack by North Korea were understandable given a slew of rocket tests by North Korea, along with South Korean military’s activities in the western coastal areas.

North Korea fired over 90 ballistic and other missiles in 2022, its highest number for any single year. South Korea tested a rocket without any public warning in December in Taean County, South Chungcheong, a southwestern part of the country, causing considerable panic and worries about UFOs.

The KMA initially reported the earthquake’s magnitude as 4.0 but later adjusted it to 3.7. An aftershock with a magnitude of 1.2 followed, according to the KMA.

Although some earthquakes with a magnitude of over 4.0 have occurred in the sea west of Incheon in the past — in Baengnyeong and Yeonpyeong Island — it was unusual for such a large earthquake to occur so close to Incheon, according to the KMA.

The recent quake follows a 4.1-magnitude earthquake that struck Goesan County in North Chungcheong last Oct. 29.

On a scale up to 12, a magnitude 4 quake will allow people indoors to feel shaking, even waking them from sleep. Windows and plates may shake, according to the KMA.

The quake was the 81st largest earthquake occurring on the Korean Peninsula since 1978.

BY CHEON KWON-PIL, SHIM SEOK-YONG, LEE BYUNG-JUN, CHO JUNG-WOO [cho.jungwoo1@joongang.co.kr]