Seismotech’s mission is providing solutions to difficult exploration problems. Among all provided solutions, Passive Seismic methodologies are our expertise. In that scope, we have developed an extended Passive Seismic exploration toolbox, comprising a number of different, yet complementary Passive Seismic techniques.
Passive Seismic Tomography is the gem in our exploration toolbox. A methodology originating from regional seismology, downscaled after years of experience at an exploration level. Easily applicable, cost effective and environmentally friendly, it is a robust exploration alternative, in cases where conventional practices wouldn’t be an option, either due to block size, penetration issues, budget limitations, accessibility and/or environmental restrictions.
Seismotech has already applied Passive Seismic Tomography in a number of “mission impossible” cases worldwide. We have managed to provide answers in difficult geological settings, from thrust-belt zones and evaporitic environments to massive sedimentary deposits, as well as in extreme morphologies, from tropical jungles to harsh mountainous areas and environmentally sensitive zones. Our clients have acquired impressive results, both at a reconnaissance level, where we have delineated the 3D structural image of enormous areas of interest at limited time and budget, as well as at a reservoir scale, where we were able to define productive and non-productive zones around known productive structures.
Having in mind that, in order for the methodology to be applied, the area of interest has to be tectonically active, Passive Seismic Tomography is an excellent all-terrain, all-weather exploration tool for those areas, capable of giving answers in difficult exploration problems.
However, our Passive Seismic exploration toolbox is not limited to Passive Seismic Tomography. Surface Wave Tomography constitutes an additional technique that is being applied, in order to obtain valuable information about the medium. Surface Wave Tomography, using earthquakes as seismic sources, is well established in crustal studies and there has been a great development in the relevant processing and interpretation techniques. Seismotech has successfully applied Surface Wave Tomography in imaging “shallow” depths (0-10km), using short-period Rayleigh waves of regional and teleseismic events.
Another important technique included in our Passive Seismic methodologies’ toolbox is the Receiver Function method, which is a powerful imaging tool of the earth’s crust and upper mantle. Receiver functions are time series which show the relative response of the Earth’s structure near the receiver, by exploiting the P- to S- wave conversion due to the existence of velocity discontinuities. Seismotech has already developed all the necessary computational tools to apply the Receiver Function method at an exploration scale, by exploiting regional and teleseismic events.
Last, but not least, Seismotech applies an "earthquake-independent" imaging technique, based on extracting the seismic response solely between receivers. This technique, widely known as Ambient Noise Tomography, is mainly used jointly with the aforementioned Passive Seismic methodologies. Ambient Noise Tomography is considered as an alternative tool, able to provide complementary geophysical information of the subsurface, by significantly improving the lateral resolution in areas with poor ray coverage. The specific method is particularly useful and advantageous within the context of our modern passive networks, where computing the cross-correlations between all possible pairs of stations results in very dense and azimuthally well distributed ray-path coverage.