Plain language summary
An approximately 40-km long high-resolution reflection seismic profile
was acquired in the metropolitan area of Seoul in South Korea for the
purpose of in-depth fault system imaging in a highly noisy and
challenging urban environment. Two different types of receivers were
used simultaneously to achieve good results from both shallow and deep
structures. Processing results have good quality and are complemented
with 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 structure underlying a domed-shaped
structure is interpreted as a fault, and could project to the known
surface position of the Pocheon fault. A domed-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 be connected and
jointly evolved. Results from the Wangsukcheon fault are also present in
the data and it is interpreted to approximately dip 60 degrees to the
east, in an opposite direction to the two other faults.