Development of passive seismic interferometry to study shallow subsurface structure

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Wetteri auditorium (IT115), Linnanmaa, University of Oulu

Topic of the dissertation

Development of passive seismic interferometry to study shallow subsurface structure

Doctoral candidate

Master of Science Nikita Afonin

Faculty and unit

University of Oulu Graduate School, Faculty of Technology, Oulu Mining School

Subject of study

Geophysics

Opponent

Professor Florent Brenguier, Grenoble Alpes University, France

Custos

Professor Elena Kozlovskaya, University of Oulu

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Development of passive seismic methods to study shallow subsurface structure

Knowledge about structure and mechanical properties of the shallow part of the geological medium is important in such applied tasks as mineral exploration, seismic hazard assessment, geotechnical site investigations and geoenergy projects.

Non-invasive methods, such as the applied geophysical techniques, are capable to obtain this knowledge with expanded special and temporal resolution. Among these geophysical methods, seismic methods are widely used for such purposes because of existing relationship between seismic velocities and mechanical and hydrological properties of the rock material.

Traditionally seismic methods, use vibrations of the Earth’s surface, produced by controlled seismic sources such as hammers, vibrators, blasts, etc. In some cases, for example areas close to industrial objects, remote or urban areas, usage of controlled sources is difficult or practically impossible, because of logistical difficulties, restrictions in natural protected areas or high level of seismic or acoustic noise, produced by human or industrial activity. This noise recorded by seismic sensors together with signal of controlled source makes it difficult or impossible to process and interpretate recorded seismic data.

One of the ways to solve this problem is an ambient noise passive seismic interferometry. It is a method, that modifies the recorded data so that it resembles controlled source data. This can then be used to study the inner structure of the geological medium. Ambient seismic noise can be generated by transportation, mining activity or by natural sources, like earthquakes.

The main objective of this doctoral research was to investigate the capabilities of passive seismic interferometry and develop new processing algorithms to study the near-surface structure of geological environments, especially in ambient noise conditions typical for Finland.

These new developed algorithms for passive seismic data processing provide information about the near-surface structure and its elastic and anelastic properties. Effectiveness of these developed algorithms has been demonstrated on several case studies conducted in different parts of Finland: e.g., Pyhäsalmi mine, Kuusamo and Sodankylä area.
Last updated: 31.10.2022