Analysis of Crustal Deformation on the Korea Peninsula after the 2011 Tohoku Earthquake

Abstract

The U.S. Geological Survey (USGS) announced that an earthquake of 9.0 magnitude had occurred near the east coast of Japan on March 11, 2011, resulting in a displacement of the crust of about 2.4 meters. The Korean peninsula is located on the Eurasian tectonic plate that stretches out to Japan; therefore, there is a high possibility of being affected by an earthquake. The Korean GPS CORS network operated by the National Geographic Information Institute (NGII) was processed for ten days before and after the earthquake. Both static and kinematic baseline processing were tested for the determination of crustal deformation. The static baseline processing was performed in two scenarios: 1) fixing three IGS stations in China, Mongolia and Russia; 2) fixing SUWN, one of the CORS networks in Korea, in order to effectively verify crustal deformation. All data processing was carried out using Bernese V5.0. The test results show that most of the parts of the Korean peninsula have moved to the east, ranging 1.2 to 5.6 cm, compared to the final solution of the day before the earthquake. The stations, such as DOKD and ULLE that are established on the islands closer to the epicenter, have clearly moved the largest amounts. Furthermore, the station CHJU, located on the southwestern part of Korea, presents relatively small changes. The relative positioning between CORS confirms the fact that there were internal distortions of the Korean peninsula to some extent. In addition, the 30-second interval kinematic processing of CORS data gives an indication of earthquake signals with some delays depending on the distance from the epicenter.

Long-term evolution of intraplate seismicity in stress shadows after a megathrust

“…The peak ground acceleration reaches 2.33 cm/s 2 in the southwestern peninsula. The lithosphere around the peninsula was dislocated by 1-6 cm in the direction to the epicenter, and was uplifted by 0.2-0.8 cm (Kim and Bae, 2012;Zhao et al, 2012) (Fig. 1(c) and (d)).…”

Time-advanced occurrence of moderate-size earthquakes in a stable intraplate region after a megathrust earthquake and their seismic properties

“…The 2011 Tohoku-Oki megathrust earthquake produced coseismic displacements of ~4 cm around the east coast and ~2 cm around the west coast of the Korean Peninsula (Fig. 1 ) 11 , 13 , 14 . Comparable strengths of postseismic displacements followed the coseismic displacements for more than 3 years 12 , 15 .…”

A Secondary Zone of Uplift Due to Megathrust Earthquakes

“…Together with the apparent occurrence of a mainly coseismic secondary zone of uplift, it seems this could occur at least during-or within the few days following-the earthquake. This might be observed on the Korean peninsula, where uplift is only observed for the five days following the 2011 M9.0 Tohoku earthquake (Kim and Bae 2012). Nonetheless, the penetration of the slab into the mantle will be at least partially delayed, since on both sides of the slab the mantle resists its penetration as it does for the overriding plate.…”