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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.

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The increasing global interest in geologic carbon storage as a feasible way of reducing CO2 atmospheric levels requires extensive onshore high-resolution seismic investigations to characterize suitable storage sites, for example, close to major CO2 emitters. To partly address this challenge and to acquire quality data at shallower and greater depths in a cost and time-effective approach, a tailored acquisition scheme was adopted and tested at a candidate site in Stenlille, Denmark. The survey aims at understanding whether an anticline reservoir structure known to exist at a 1000 m depth can serve for long-term CO2 storage and presents the structural integrity for this purpose. The data were recorded using a combination of nodal arrays, spaced at 10 m in a fixed geometry, and a set of more closely (2 m) spaced digital recorders, mounted on a landstreamer, which was moved at each shot location. Two 12 t mini vibrators were used as seismic sources. The nodal and landstreamer data sets are compared and combined into a unique data set for reflection imaging purposes along five profiles with a total length of approximately 12 km. The seismic sections obtained using this tailored combination of different recorders provide images of the entire shallow and deeper structures with an unprecedented resolution at the different depth levels necessary to assess the full potential of the suggested CO2 storage reservoir. The results significantly increase the existing knowledge of the extent and structural closure of the reservoir as well as a possible fault, all of which are critical for future risk analysis and planning of the storage.

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