Reflection/Refraction Seismology

Abstract

SynonymsControlled-source seismology; Multichannel reflection seismics; Wide-angle reflection/refraction profiling (WARRP) DefinitionsMethods to image and to physically parameterize the subsurface geologic structures and conditions by means of artificially generated shock waves that travel through the subsurface and return to the surface. OverviewControlled-source seismology comprises a variety of geophysical methods to image and to physically parameterize the subsurface geologic structures and conditions. All these methods base upon the principle that artificially generated shock waves travel through the subsurface and that the returned signal can be analyzed regarding the properties of the subsurface. During the last decades the discrepancies between marine seismic equipment as used by the academic marine research community and that used by the hydrocarbon (HC) exploration industry increased significantly, caused by different research targets and the simple fact that gear commonly used for HC exploration is much too costly. In this chapter we will focus on those systems which are typical for academic marine research.In principle, seismic data acquisition requires an energy source, a receiver, and a recording system. The two most important seismic methods are reflection and refraction seismology (Fig. 1).Reflection seismologists deal mainly with steep angle reflections, which means that the source to receiver distance is small compared to the target depth. This method utilizes the fact that a small part of the down-going energy is reflected on geological layer boundaries. The main fraction of the energy is transmitted and travels deeper where reflections occur at the next layer boundary and so on. This method results in a good vertical and horizontal structural resolution of the subsurface. Earth scientists benefit from the technical and methodical developments of the exploration industry which uses reflection seismology for the detection of oil and gas in depths of up to several kilometers below the seafloor.

Late Cretaceous to recent tectonic evolution of the North German Basin and the transition zone to the Baltic Shield/southwest Baltic Sea

“…Mesozoic and Tertiary deposits reveal anticlines, which are quite similar to those described by Al Hseinat and Hübscher (2014). The anticlines are more abundant in the northern Bays of Kiel and Mecklenburg, which is near the northwestern margin of the North German Basin (Fig.…”

“…Tertiary to recent halokinetics and faulting in the supraZechstein succession in the southwest Baltic Sea are due to the Neogene to recent NW-SE directed extension, the present-day orientation (Figs. 1 and 3; Al Hseinat and Hübscher, 2014;Al Hseinat et al, 2016).…”

“…Seismic sections cover large scale area within the southwest Baltic Sea, mostly between the Bay of Kiel and the Tornquist Zone with a total length of ~20.000 km. For a general description of the marine seismic method see Hübscher and Gohl (2014).…”

“…These authors pointed out that the eastern SW-NE trending marginal Eastholstein Trough evolved during this rifting phase. Based on Al Hseinat and Hübscher (2014), the almost N-S striking Kossau Fault within the Bay of Kiel represents a north prolongation of the Eastholstein Mecklenburg Block (Fig. 2b).…”

The Hecataeus Rise, easternmost Mediterranean: A structural record of Miocene-Quaternary convergence and incipient continent-continent-collision at the African-Anatolian plate boundary

“…Shots were fired at a constant time interval of 6e9 s, producing a seismic pulse with dominant frequencies centered around 100 Hz. A 24-channel analogue streamer with an active length of 600 m and a group spacing of 25 m recorded data at a sample rate of 1 ms. For a general introduction to marine reflection seismics see Hübscher and Gohl (2014).…”