ORCID Profile
0000-0003-1405-6307
Current Organisation
Luxembourg Institute of Science and Technology
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Publisher: Seismological Society of America (SSA)
Date: 07-06-2022
DOI: 10.1785/0120210197
Abstract: The crustal structure and Quaternary fault zone in the Seoul metropolitan area are investigated using a joint inversion that combines the receiver functions with surface wave dispersion based on seismic data from densely deployed seismic arrays. The uncertainty in inverted models is examined through a set of synthetic experiments. Synthetic tests and comparisons with other methods verify the observed crustal features. The Moho depths range between 28.7 and 32.8 km with relatively shallow depths in the central Seoul metropolitan area. The VP/VS ratio varies between 1.67 and 1.85. A Conrad discontinuity with a weak velocity increase is present at a depth of ∼20 km. Low-velocity anomalies appear at depths of ∼3 km and 6–11 km along the Chugaryeong fault zone and fault junction area. Apparent shear wave velocity contrasts appear across the fault zone where earthquakes are clustered. A high-velocity block in the western Seoul metropolitan area lies along the fault zone that runs across western Seoul. The shear wave velocity models and seismicity suggest that the fault zone may extend to a depth of 11 km at least.
Publisher: Wiley
Date: 18-02-2022
Abstract: Microbial necromass is a large, dynamic and persistent component of soil organic carbon, the dominant terrestrial carbon pool. Quantification of necromass carbon stocks and its susceptibility to global change is becoming standard practice in soil carbon research. However, the typical proxies used for necromass carbon do not reveal the dynamic nature of necromass carbon flows and transformations within soil that ultimately determine necromass persistence. In this review, we define and deconstruct four stages of the necromass continuum: production, recycling, stabilization and destabilization. Current understanding of necromass dynamics is described for each continuum stage. We highlight recent advances, methodological limitations and knowledge gaps which need to be addressed to determine necromass pool sizes and transformations. We discuss the dominant controls on necromass process rates and aspects of soil microscale structure including biofilms and food web interactions. The relative importance of each stage of the continuum is then compared in contrasting ecosystems and for climate change drivers. From the perspective of the continuum, we draw three conclusions to inform future research. First, controls on necromass persistence are more clearly defined when viewed through the lens of the continuum second, destabilization is the least understood stage of the continuum with recycling also poorly evidenced outside of a few ecosystems and third, the response of necromass process rates to climate change is unresolved for most continuum stages and ecosystems. Future mechanistic research focused on the role of biotic and abiotic soil microscale structure in determining necromass process rates and the relative importance of organo–mineral and organo–organo interactions can inform necromass persistence in different climate change scenarios. Our review demonstrates that deconstructing the necromass continuum is key to predicting the vulnerability and persistence of necromass carbon in a changing world. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: American Geophysical Union (AGU)
Date: 09-2022
DOI: 10.1029/2022EA002464
Abstract: An approximately 40‐km long high‐resolution reflection seismic profile (P3) was acquired in the metropolitan area of Seoul in South Korea for the purpose of fault system imaging in a highly noisy and challenging urban environment. Two 12t seismic vibrators (mini‐vibs) were used as the seismic source. Data were recorded using a dual element seismic spread 20 m spaced 421 wireless seismic recorders connected to 10 Hz geophones and 20 micro‐electro‐mechanical‐based landstreamer sensors (2 m sensor spacing) attached to one of the vibrators. The purpose of the dual spread employed was to delineate both near‐surface and deep structures. The processing results show good quality and the processing work was complemented by different analysis to further constraints the geological interpretation. The survey results provide evidence for the 3D geometry of three fault systems, including Chugaryeong, Pocheon, and Wangsukcheon faults. A gently westerly dipping set of reflectivity underlying a dome‐shaped package of reflectivity is interpreted as a fault, and could project to the known surface position of the Pocheon fault. The dome‐shaped reflectivity is interpreted as folded and faulted dyke or sill systems. Downward continuation of the interpreted fault intersects the sub‐vertical Chugaryeong fault in a zone where the current seismicity is observed, suggesting that these two major fault systems may have jointly evolved in the form of splay faults. Reflections from the Wangsukcheon fault are also present in the data and interpreted to dip approximately 60° to the east, in an opposite direction to the two other faults.
Publisher: Seismological Society of America (SSA)
Date: 10-10-2023
DOI: 10.1785/0120230015
Publisher: Wiley
Date: 27-06-2022
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jeongin Lee.