Towards Geothermal Reservoir Characterization and Monitoring Through Seismic (Ambient Noise) and Geodetic (INSAR) Imaging: Torfajökull Volcano and Reykjanes Peninsula, Iceland.

After decades of oil, gas, and coal exploitation, we have learned about some of the unpleasant aftereffects of subsurface resource exploration. Adverse long-term impacts, some known during exploration periods, others only afterwards, may include induced seismicity, land subsidence, or even sinkholes. While geothermal is currently seen as a...

Elastic wavefield inversion by the alternating update method

Full-waveform inversion is a promising tool for a wide range of imaging scenario, in that it has the potential to harness the non-linear relationship between model parameters and data (as opposed to traditional methodologies), in order to produce truly quantitative results. Non-linearity represents an opportunity, in this sense, but it also...

Anisotropic Joint Migration Inversion: Automatic estimation of reflectivities and anisotropic velocities

One of the most crucial estimates obtained from reflection seismology is the seismic image. It provides a map of the subsurface reflectivities. However, in order to construct an accurate map an accurate propagation velocity model is needed. For simple geologic environments an isotropic velocity model is sufficient, however, for complex geologic...

Seismic Waveform Inversion: Bump functional, parameterization analysis and imaging ahead of a tunnel-boring machine

During a seismic experiment, mechanical waves are usually generated by various manmade sources. These waves propagate in the subsurface and are recorded at receivers. Modern seismic exploration methods analyze them to infer the mechanical properties of the subsurface; this is commonly referred as quantitative imaging. These properties assist in...

Full Wavefield Migration of Vertical Seismic Profiling data

Until now, in most seismic imaging technologies, both surface and internal multiples are considered as noise. In today’s industrial practice, we see various methods for suppressing multiples before migration. This means that only a fraction of the recorded wavefield is used in imaging. In this thesis, we present a method termed full wavefield...

Subsurface offset behaviour in velocity analysis with extended reflectivity images

Migration velocity analysis with the constant-density acoustic wave equation can be accomplished by the focusing of extended migration images, obtained by introducing a subsurface shift in the imaging condition. A reflector in a wrong velocity model will show up as a curve in the extended image. In the correct model, it should collapse to a...

Body-wave seismic interferometry applied to earthquake- and storm-induced wavefield

Seismology is the study of the vibration of the Earth. Seismologists pay much attention to the main source of Earth vibration: earthquakes. But also other seismic sources, like mining blasts, ocean storms and windmills, are studied. All these sources induce seismic waves, which can eventually be recorded as ground vibrations. These seismic...

Correlation-based seismic velocity inversion

Most of our knowledge of the subsurface comes from the measurement of quantities that are indirectly related to the earth’s structure. Examples are seismic waves, gravity and electromagnetic waves. We consider the use of seismic waves for inference of structural information on an exploration scale. The seismic waves are generated by placing...

One-step estimation of focusing operators for 3D seismic data

The main subject of this thesis is the estimation of focusing operators, which are the kinematical part of the Green's function from reflector points in the subsurface, called focal points, to a grid of points located at the acquisition surface. This estimation process is data-driven and does not explicitly involve the estimation of a subsurface...