Seogwipo earthquake in 2021
The 2021 Seogwipo earthquake or the 2021 Jeju earthquake was an earthquake with a magnitude of M4.9 and a moment of M4.8 on the Richter scale that occurred on December 14, 2021 at 17:19:14 in an area 41km southwest of Seogwipo, Jeju Island, South Korea. The Korea Meteorological Administration initially measured the magnitude of the earthquake as 5.3, but corrected it to 4.9 in 3 minutes. As a result of this earthquake, a vibration of maximum V (Roman letters 5) was detected in Jeju based on the modified Mercalli seismic intensity scale. This day's earthquake was the largest earthquake on the Korean Peninsula in 2021 and the largest earthquake that occurred near Jeju Island. It is the largest since the 3.9 magnitude earthquake in
This earthquake is a strike-fault type earthquake in the southwest sea area of Jeju Island, which is pressured along the northwest-southeast or east-west direction, which is almost in the north-south direction. Also, it appears to have occurred in the north-south strike fault existing in the western sea of Jeju. Because the fault moved horizontally, it is analyzed that the damage caused by the earthquake was not large. However, it is not known whether the fault that caused the earthquake was caused by an active fault or a small fault. The nearby waters were shallow, so no tsunami occurred. The maximum PGA of 6.891%g was observed at the Marado Observatory.
After the earthquake of magnitude 4.9 on December 14th, five aftershocks occurred near the epicenter, including the largest earthquake of magnitude 2.7. The Korea Meteorological Administration predicted that the Jeju earthquake is quite strong and it will take some time for the crust to stabilize in the vicinity, and that earthquakes with a magnitude of 3.0 or less will continue to occur. At 3 pm on December 15, an aftershock of magnitude 2.8 occurred near the epicenter. As of January 2, a total of 20 aftershocks have occurred. Most of them are micro-earthquakes. The list of aftershocks is as follows. Most of the aftershocks occur on the day of the main earthquake, and thereafter, it tends to decrease sharply. The most recent aftershock was the 1.7 magnitude earthquake on December 22, 2021.
List of major aftershocks
Progress in each place
In addition, as a result of this earthquake, an earthquake with a seismic intensity of 1 according to the Japan Meteorological Agency's seismic intensity scale was observed in Koto City, Nagasaki Prefecture, Japan.
Building shaking was detected throughout Jeju Island. As soon as the earthquake occurred, thousands of people ran out of the duty-free shop at Jeju Convention Center in Seogwipo. Reports were reported that the entire building was shaken in Wando-gun and other areas. In addition, the Seoul Fire and Disaster Headquarters received a report that a multi-family house in Cheonho-dong, Gangdong-gu, Seoul at 5:22 pm and a villa in Sangbong-dong, Jungnang-gu, Seoul shook at 5:24 pm. collapsed
Characteristics of earthquakes near Jeju Island
Compared to other regions in Korea, Jeju Island cannot be said to have high seismic activity, but based on the Korea Meteorological Administration's list of domestic earthquakes, the waters near Jeju Island have long been prone to earthquakes. A total of 89 earthquakes occurred from 1978 to just before the earthquake on December 14, 2021, and earthquakes occurred every year from 2009 to 10 years. The frequency of earthquakes has been increasing gradually since 2003, and the epicenter is spread out in several places in the eastern and western seas of Jeju Island. The most recent earthquake with a magnitude of 2.0 or greater occurred on October 20, 2019, two years ago, and after that, only micro-earthquakes with a magnitude of 2 or less will occur until 2021.