홍태경 교수

The crustally guided shear wave, Lg , is typically the most prominent phase of a nuclear explosion at regional distance. This Lg phase is analyzed often to discriminate a nuclear explosion from a natural earthquake. In addition, the Lg phase allows us to determine the size of the detonation. A nuclear explosion test in North Korea was conducted on 9 October 2006. The epicenter was located close to the eastern shore of the Korean Peninsula, resulting in raypaths that vary significantly according

Abstract The seismicity in the Korean Peninsula has increased since the 2011 M w 9.0 Tohoku‐Oki megathrust earthquake. Two strike‐slip earthquakes with magnitudes of M L 5.1 and 5.8 occurred in the southeastern Korean Peninsula on 12 September 2016. The two events occurred within 48 min. The M L 5.8 earthquake was the largest event in the Korean Peninsula since 1978 when national seismic monitoring began. Both events produced strong high‐frequency ground motions. More than 500 aftershocks with l

Abstract The distance-dependent coseismic and postseismic displacements produced by the 2011 M W 9.0 Tohoku-Oki megathrust earthquake caused medium weakening and stress perturbation in the crust around the Korean Peninsula, increasing the seismicity with successive M L 5-level earthquakes at the outskirts of high seismicity regions. The average M L 5-level occurrence rate prior to the megathrust earthquake was 0.15 yr −1 (0.05–0.35 yr −1 at a 95% confidence level), and the rate has increased to

Research Article| October 01, 2013 Probabilistic Analysis of the Korean Historical Earthquake Records Soung Eil Houng; Soung Eil Houng Yonsei University, Department of Earth System Sciences, 50 Yonsei‐ro, Seodaemun‐gu, Seoul 120‐749, South Koreatkhong@yonsei.ac.kr Search for other works by this author on: GSW Google Scholar Tae‐Kyung Hong Tae‐Kyung Hong Yonsei University, Department of Earth System Sciences, 50 Yonsei‐ro, Seodaemun‐gu, Seoul 120‐749, South Koreatkhong@yonsei.ac.kr Search for oth

Abstract The crustally-guided shear wave, Lg , is typically the strongest phase at regional distances. Lg phases are analyzed often for estimation of magnitudes of regional events. The variation of Lg in regions with both continental and oceanic environments has been rarely investigated. We investigate Lg attenuation in a plate-margin area around Korea and Japan that is encompassed by seas and oceans. The mean quality factor of Lg at 1 Hz ( Q 0 ) is 498. The geometrical-spreading exponent term i

Abstract A recent dense deployment of seismic stations in South Korea and Japan allows regional seismic imaging of the far-east Asian region that experienced continental collisions and riftings. We perform seismic imaging based on a mantle-lid P -wave ( Pn ) travel-time tomography to exploit the tectonic imprints in the lithosphere. The average Pn velocity in the region is estimated to be 7.95±0.03 km/sec. The inverted Pn velocities illuminate the tectonic structures. High velocities of ∼8.15 km

The passage of seismic waves through highly heterogeneous media leads to significant scattering of seismic energy and an apparent attenuation of seismic signals emerging from the heterogeneous zone. The size of this scattering attenuation depends on the correlation properties of the medium, the rates of P- and S-wave velocities, and frequency content of the incident waves. An estimate of the effect can be obtained using single scattering theory (first-order Born approximation) for path deviation

Abstract The 9 October 2006 underground nuclear explosion (UNE) test in North Korea was well monitored by dense regional seismic stations in South Korea, Japan, and China. This observation allows extensive investigation of the regional source properties of the UNE. The moment for isotropically radiated energy from the UNE is estimated to be 2.92×10 14 N m. Source spectra of major regional phases from the UNE are studied by inverting for apparent moments, corner frequencies, overshoot parameters,

After the devastating Tohoku-Oki earthquake (Mw 9.0, 2011) in Japan, the Korean Peninsula has experienced a higher number of large, plus Mw 5.0, earthquakes than recorded in the preceding half century of modern monitoring. In addition, seismicity has dramatically increased along with seismic waves arriving later than prior to the 2011 Tohoku-Oki earthquake, suggesting that the Korean crust has notably been perturbed. South Korea is densely populated, hence knowledge about active faults and earth

Abstract The average shear‐wave velocity within the top 30 m from the surface, V S 30 , represents site characteristics including the soil classification and site amplification that are essential information for building codes and seismic design. A novel method to determine a V S 30 model based on a composite analysis of borehole standard penetration test numbers (SPT N) and horizontal‐to‐vertical (H/V) spectral ambient noise ratios is introduced. A national V S 30 model for South Korea is deter

Abstract Quaternary faults run across the Seoul metropolitan area that is the highest population region in the Korean Peninsula. Active fault identification and seismic hazard potential assessment are crucial for public safety. Densely deployed permanent and temporal seismic stations enabled us to detect micro to small earthquakes, allowing us to identify earthquake‐spawning faults in Seoul metropolitan area. The source parameters of 455 earthquakes in 2004–2020 are refined. The Gutenberg‐Richte

The mechanism of regional shear wave excitation by underground nuclear explosions (UNE), a long‐standing issue in nuclear seismology, is investigated by studying the phase composition of regional waves from clustered UNE. Regional seismic waves from 67 UNE at the Balapan test site of Kazakhstan, recorded at station Borovoye, are analyzed with a source array technique under the reciprocity theorem. This analysis allows one to obtain the phase velocity composition of the plane waves leaving the so